Exam 4

Question 1

What is the overall function of the immune system? How do immune cells recognize self vs. non-self?

Answer 1

The role of the immune system is to differentiate between home cells and outsider cells, and to defend the body from pathogenic outsiders. This system distinguishes between “self” and “other” through the recognition of surface markers on cells. MHCs (major histocompatibility complex molecules) or self markers are found on “self” cells and are made of sugars or proteins (or a combination of the two). PAMPs (pathogen-associated molecular patterns) are markers on “other” or “non-self” cells which allow the immune system to recognize certain invaders as such.

Question 2

What are three different lines of defense? Which immune system (innate vs. adaptive) do they belong to?

Answer 2

Physical and Chemical Barriers: This includes the skin, mucous membranes, and various secretions (e.g. saliva, tears, stomach acid) that prevent pathogens from entering the body. This is a part of the innate immune system.

Innate Immune Response: This includes immune cells such as phagocytes, natural killer cells, and complement proteins that recognize and attack pathogens. This is also a part of the innate immune system.

Adaptive Immune Response: This involves the production of antibodies and the activation of T cells that specifically recognize and target pathogens. This is a part of the adaptive immune system.

The first two lines of defense (physical and chemical barriers and innate immune response) belong to the innate immune system, while the third line of defense (adaptive immune response) belongs to the adaptive immune system.

Question 3

Describe two physical barriers and three chemical barriers associated with the innate immunity.

Answer 3

Physical Barriers -

1- Mucous membranes- Mucus can help trap microbes from entering the body

2- Skin- Dead skin cells can help remove microbes from the body

Chemical Barriers-

1- The pH in the vagina is very acidic which creates a chemical barriers like Candida

2- Lysozyme is an enzyme that eliminates microbes and is present in eyes and tears

3- Fatty acids are present in the earwax which can lower pH

Question 4

In what ways is a phagocyte a tiny container of disinfectants? Briefly explain.

Answer 4

A phagocyte is a cell that protects the body by ingesting harmful substances that are foreign in the body. It’s a tiny container of disinfectants because it breaks down the bacteria into pus and allows it to be excreted from the body and cleaned out of the lymphatic system.

Question 5

What is the complement system? Summarize three outcomes of complement activation.

Answer 5

The complement system is the sum of more than 30 proteins that function in complementary ways to the innate immune systems response and help trigger the adaptive immune response.

The 3 outcomes of complement activation are:

1. Inflammation: The complement system has the ability to attract immune cells via chemoreceptors to the site of infection or tissue damage. As immune cells respond to the site and enact the immune response inflammation occurs. Uncontrolled inflammation can lead to tissue damage, that is why it is important that the complement system has other methods of activation.
2. Opsonization: The complement system is able to enhance the process of phagocytosis by coating the surface of a pathogen with c3b proteins.
3. Cytolysis: The complement system can create a membrane attack complex (MAC) that essentially punches holes in the membranes of bacterial cells, resulting swelling and eventually the bursting of the cell. This is known as cell lysis.

Question 6

What does MAC stand for, and what effect does it have on bacterial cells?

Answer 6

MAC stands for membrane attack complex, which punctures holes in the cell membrane of the invading pathogen causing it to swell and burst.

Question 7

What kinds of infections usually result in production of interferon? How does the production of IFN protect uninfected cells?

Answer 7

Viral infections usually result in the production of interferon. The production of interferon protects uninfected cells through binding the receptors of the neoghbors of the infected cells. preventing the cells from producing viral proteins, thus interfering with viral production, hence the name interferon.

Question 8

What are the granulocytes and agranulocytes of the immune system? Describe each cell’s morphology and function.

Answer 8

Granulocytes are the type of white blood cells that are present in the cytoplasm, with granules in them. There are three types of granulocytes: Neutrophils: Which are made up of 3-5 lobes connected by thin strands. The most abundant type of WBCs. They are in charge of killing bacteria, fungi, and foreign debris. Then we got Eosinophils: They have a two-lobe nucleus. They’re involved in killing parasites, and cancer cells and involved in allergic responses. They stain bright pink to red. Lastly, we have Basophils: They usually have more than one lobe nucleus and would stain dark blue to purple. They’re involved in allergic responses and releasing heparin to limit the size of a forming blood clot.

A second type of WBCs is Agranulocytes which by the name it means it doesn’t have granules in the cell, and they’re of two different types. First, Lymphocytes: They have a round nucleus. Involved in fighting viruses and making antibodies. Then we have Monocytes: They’re known to be the biggest cell in size. They have a kidney bean-shaped nucleus. They clean up damaged cells. When a pathogen enters the body, they turn into macrophages, calling on other cells to help treat injury and prevent infections.

Question 9

How do white blood cells squeeze through the blood vessel? What is this phenomenon called?

Answer 9

WBC’s can deform their cell structure, and many have multi-nucleated or multi-lobed nuclei that allow them to better fit through the endothelial cells that make up the walls of blood vessels. This is called extravasation, or diapedesis.

The process by which white blood cells squeeze through the walls of blood vessels to reach the site of infection or injury is called diapedesis or extravasation.

During diapedesis, white blood cells use a process called leukocyte adhesion and transmigration to move through the blood vessel walls. First, the white blood cells roll along the endothelial cells that line the blood vessels. Then, they adhere to the endothelial cells through a process called leukocyte adhesion, which involves the interaction between adhesion molecules on both the white blood cells and the endothelial cells. Finally, the white blood cells migrate through the endothelial cells and basement membrane and into the surrounding tissue through a process called transmigration or paracellular migration.

This process is facilitated by the formation of temporary gaps between the endothelial cells and the loosening of the basement membrane, which allows the white blood cells to squeeze through the walls of the blood vessels and reach the site of infection or injury.

Question 10

What do PAMP and PRR stand for? What are their roles in phagocytosis?

Answer 10

PAMP stands for pathogen-associated molecular patterns (PAMPs):
These are markers on pathogens that help immune cells recognize pathogens as “non-self” and begin phagocytosis. Some examples of (PAMPS) include:
peptidoglycan, found in bacterial cell walls;
flagellin, a protein found in bacterial flagella;
lipopolysaccharide (LPS) from the outer membrane of gram-negative bacteria;
lipopeptides, molecules expressed by most bacteria; and
nucleic acids such as viral DNA or RNA.
PRR stands for pattern recognition receptors (PRRs) and they work by helping phagocytes to detect PAMPS. Some are located on the outside of phagocytes, others can be found on organelles or embedded in the membrane.

Question 11

Describe the different steps of phagocytosis. What is a high neutrophil count in blood a sign of? What is pus made of?

Answer 11

1. Injured cells secrete chemical signals
2. Resident macrophages engulf pathogens and release cytokines
3. Endothelial cells increase expression of adhesion molecules and receptors
4. Leukocytes stick to endothelial cells and slow down
5. Leukocytes squeeze through the junction between endothelial cells
6. Leukocytes release chemicals to kill pathogens and engulf them

High neutrophil count in blood is a sign that the body is fighting an infection. Pus buildup is when cellular debris and bacteria at the site of infection is observed. It is a sign that the immune defense is activated against an infection.

Question 12

Why is the evasion of phagocytosis a type of virulence factor? Use a specific example to explain. (HINT: we have encountered several pathogens that have different mechanisms for phagocytosis evasion. Different students can use different microbes to answer this question).

Answer 12

Phagocytosis is part of the immune response, during which immune cells such as macrophages engulf and digest invading pathogens. Many pathogenic microorganisms have developed strategies around phagocytosis, which is makes it a type of virulence factor.

One example of phagocytosis evasion as a virulence factor is Staphylococcus aureus. S. aureus has several mechanisms to avoid phagocytosis, including the production of cell surface proteins that prevent recognition and binding by immune cells.

Question 13

What do rubor, calor, tumor and dolor mean in acute inflammation? What is the cause of each in the inflammatory process?

Answer 13

Rubor means redness, caused from vasodilation and increased blood flow. Calor means heat, caused by increased blood flow due to capillary widening. Tumor means swelling, caused by increased permeability of blood vessels that causes leakage of plasma proteins and fluid into the tissues. Dolor means pain, caused by the stimulation of nerve pain receptors in the tissue.

Question 14

What are pyrogens? List three functions of fever.

Answer 14

Pyrogens are chemicals that effectively alter the “thermostat setting” of the hypothalamus, elevating body temperature and causing fever. The functions of fever include enhancing the innate immune defenses by stimulating leukocytes to kill pathogens, inhibiting the growth of many pathogens due to the rise in body temperature, and stimulating the release of iron-sequestering compounds from the liver, thereby starving out microbes that rely on iron for growth.

Question 15

What are the signs and symptoms of malaria?

Answer 15

Symptoms: Headache, Nausea, Back pain, muscular fatigue and pain, dry cough

Signs: vomiting, fever (39-41°C [102.2-105.8°F]) , chills, sweating, spleen enlargement, faint and rapid pulse

Severe malaria:

Cerebral malaria, with abnormal behavior, impairment of consciousness, seizures, coma, or other neurologic abnormalities.
Severe anemia due to hemolysis (destruction of the red blood cells)
Hemoglobinuria (hemoglobin in the urine) due to hemolysis
Acute respiratory distress syndrome (ARDS), an inflammatory reaction in the lungs that inhibits oxygen exchange, which may occur even after the parasite counts have decreased in response to treatment
Abnormalities in blood coagulation
Low blood pressure caused by cardiovascular collapse
Acute kidney injury
Hyper parasitemia, where more than 5% of the red blood cells are infected by malaria parasites
Metabolic acidosis (excessive acidity in the blood and tissue fluids), often in association with hypoglycemia

Question 16

What is the causative agent of malaria? Is it a prokaryote or an eukaryote?

Answer 16

Malaria is caused by several eukaryotic protozoan parasites in the genus Plasmodium: P. falciparum, P. knowlesi, P. malariae, P. ovale, and P. vivax.

Plasmodium belongs to the phylum apicomplexans, which are unicellular eukaryotic parasites. They have an apical complex at the end of the cell. This complex includes organelles, microtubules and vacuoles that help Plasmodium enter the host cells. Plasmodium primarily infect red blood cells. Here is an included image from the textbook showing the apical complex.

Question 17

Identify the life cycle of Plasmodium in both the human host and the mosquito host. Which stages are the infectious stage and which are the diagnostic stage?

Answer 17

During a blood meal, a malaria-infected female Anopheles mosquito inoculates sporozoitesinto the human host . Sporozoites infect liver cells and mature into schizonts , which rupture and release merozoites . After this initial replication in the liver (exo-erythrocytic schizogony ), the parasites undergo asexual multiplication in the erythrocytes (erythrocytic schizogony ). Merozoites infect red blood cells. The ring stage trophozoites mature into schizonts, which rupture releasing merozoites. Some parasites differentiate into sexual erythrocytic stages (gametocytes). Blood stage parasites are responsible for the clinical manifestations of the disease. The gametocytes, male (microgametocytes) and female (macrogametocytes), are ingested by an Anopheles mosquito during a blood meal .

The parasites’ multiplication in the mosquito is known as the sporogonic cycle. While in the mosquito’s stomach, the microgametes penetrate the macrogametes generating zygotes. The zygotes in turn become motile and elongated (ookinetes) which invade the midgut wall of the mosquito where they develop into oocysts. The oocysts grow, rupture, and release sporozoites, which make their way to the mosquito’s salivary glands. Inoculation of the sporozoites into a new human host perpetuates the malaria life cycle.

Question 18

How does having the sickle cell allele affect people’s chances of survival from malaria?

Answer 18

People can have either one copy of the sickle cell allele, two copies, or no copies at all.:

-For those who have no copies of the allele, and produce only normal A form hemoglobin, they are at a high risk for malaria.

-For those who have two copies of the allele, they produce only the abnormal S form hemoglobin, and although they are at a low risk for malaria, they will still experience a painful disease if infected.

-Carriers of the sickle cell allele, where they have one copy of the allele, and produce both A form and S form hemoglobin, have a low risk for malaria as well, and if infected will not experience severe symptoms.

Question 19

How is malaria diagnosed, prevented and treated?

Answer 19

Malaria is diagnosed by the clinical signs and symptoms, Plasmodium in blood smears, RDTs/EIAs that detect Plasmodium antigens or a PCR detecting parasite nucleic acids. Prevention includes mosquito nets, closing windows, avoid standing water and insect repellent to limit interaction with mosquitos. It is also recommended to take medicine before, during and after traveling to areas where malaria is present. There is also a malaria vaccine that was approved in 2021. Treatment may include drugs like chloroquine, atovaquone , artemether, and lumefantrine but some Plasmodium have been found resistant to antimalarial drugs. Since Plasmodium are protozoa, their cells are similar to human cells, which makes it hard to develop drugs that don’t cause symptoms to our body.

Question 20

How are adaptive immunity and innate immunity different? List the two main differences and briefly explain.

Answer 20

1. innate immune system is activated quickly and is non-specific, it does not have memory and responds to all pathogens the same
2. adaptive immune system takes longer to develop but is more specific and at risk of redundancy – adaptive. the adaptive immune system can remember pathogens and also respond differently depending on the type of pathogen.

Question 21

What are antigens and where would you find them? What are they made of? What are epitopes?

Answer 21

Antigens are any molecule or organism that generates an antibody response. They are found everywhere. They can be toxins, pollen, microbes, a molecule…and are made up of any of the macromolecules and/or lipids. Epitopes are short amino acid residue sequences (sometimes monosaccharide sequences) on antigens which antibodies recognize and with which they bind and mount an immune response.

Question 22

What is the structure of antibodies? What are the different ways that antibodies can help combat pathogens?

Answer 22

Antibodies structure has 4 polypeptide chains 2 heavy chains and 2 light chains. Each chain has consistent and variable regions. Antibodies can help combat pathogens by neutralization, opsonization, and activating complement proteins. Neutralization for example, is where the antibody binds to the pathogens to prevent it from infecting or damaging host cells.

Question 23

What are class I and class II MHC genes? Which cell types are they expressed, and what are their functions?

Answer 23

Class I and II MHC genes are involved in the immune response and plays a crucial role in presenting antigens to immune cells.

MHC (major histocompatibility complex) I present normal self-antigens molecules and abnormal (non-self) pathogens to the effector T cells that are involved in cellular immunity. They are expressed on all normal, healthy, nucleated cells which signals to the immune system that the cell is a normal “self” cell. MHC I molecules are composed of a longer α protein chain coupled with a smaller β2 microglobulin protein and only the α chain spans the cytoplasmic membrane. The α chain of the MHC I molecule folds into three separate domains: α1, α2 and α3.

MHC I molecules present antigens that is derived from intracellular pathogens such as viruses and intracellular bacteria, to cytotoxic T lymphocytes (CTLs) or CD8+ T cells. This presentation triggers an immune response which leads to the destruction of infected or abnormal cells. These molecules also help in immunosurveillance because they present self-antigens that enable the immune system to detect and eliminate cells that displays abnormal proteins, such as cancer cells.

MHC (major histocompatibility complex) II present abnormal (non-self) pathogen antigens for the initial activation of T cells. These molecules are only expressed on macrophages, dendritic cells, and B cells. MHC II molecules are composed of two protein chains (an α and a β chain) that are approximately similar in length. Both chains of the MHC II molecule possess portions that span the plasma membrane, and each chain folds into two separate domains: α1 and α2, and β1, and β2.

MHC II molecules present antigens that is derived from extracellular pathogens, such as bacteria, fungi, and parasites, to helper T lymphocytes (Th cells) or CD4+ T cells. This interaction activates the immune response and stimulates various immune cells including B cells and cytotoxic T cells, in order to eliminate the pathogens. These molecules are essential for initiating and coordinating immune responses.

Question 24

Name three antigen presenting cells. What is their role in the adaptive immune system? Which classes of MHC proteins do they express and why is this important?

Answer 24

In adaptive immunity, antigen-presenting cells (APCs) play a crucial role. T-lymphocytes require these to operate properly. B-lymphocytes, macrophages, and dendritic cells are the three primary antigen-presenting cells.

B cells create antibodies.
B lymphocytes, also called B cells, create a type of protein called an antibody. These antibodies bind to pathogens or to foreign substances, such as toxins, to neutralize them.
Besides secreting antibodies, B cells express MHC class II and serve as antigen-presenting cells (APCs) for CD4+ T cells.

Generally, macrophages ingest and degrade dead cells, debris, tumor cells, and foreign materials. They promote homeostasis by responding to internal and external changes within the body, not only as phagocytes, but also through trophic, regulatory, and repair functions.
Macrophages can process and present exogenous antigens on major histocompatibility complex (MHC) class I molecules through an alternative mechanism involving the internalization of antigens and the secretion of peptides loading MHC class I molecules at the cell surface.

Dendritic cells (DCs) represent a heterogeneous family of immune cells that link innate and adaptive immunity. The main function of these innate cells is to capture, process, and present antigens to adaptive immune cells and mediate their polarization into effector cells (1)
Dendritic cells (DCs)3 are antigen-presenting cells that play a vital role in the immune system. A major function of DCs is to capture, process, and present antigens to T cells (1). To perform this task, DCs possess MHC class II (MHC-II) proteins onto which processed antigens are loaded (2).

Question 25

How do APCs activate TH cells? Draw a picture to illustrate clonal selection.

Answer 25

APCs interact with T cells to link innate and adaptive immune responses. By displaying bacterial and tumorigenic antigens on their surface via major histocompatibility complexes, APCs can directly influence the differentiation of T cells.

Question 26

What happens when a TH cell is activated? What are clonal expansion and differentiation? How long does it take?

Answer 26

After activation, T cells undergo a clonal expansion and differentiation followed by a contraction phase, once the pathogen has been cleared. Cell survival and cell death are critical for controlling the numbers of naïve T cells, effector, and memory T cells. B cell differentiation is the process by which B cells change into different types, such as plasma cells and plasma blasts. Clonal expansion is the process by which daughter cells arise from a parent cell. After a naive lymphocyte has been activated, it takes 4 to 5 days before clonal expansion is complete and the lymphocytes have differentiated into effector cells.

Question 27

During lymphocyte maturation, how does your body build immune tolerance? Do you know the consequences of failure to do so?

Answer 27

During lymphocyte maturation, the body builds immune tolerance by central tolerance. This process occurs in the thymus for T cells and in the bone for bone marrow B cells. The T cells undergo positive and negative selection, in the positive selection they are able to recognize self MIC molecules are allowed to mature and kill those who can’t. Negative selection T cells recognize self-antigens too strongly and are eliminated to prevent autoimmunity. If they don’t build this immune tolerance results in autoimmune diseases where the bodies immune system attacks the healthy organs and tissues.

Question 28

What are the main receptors on the surfaces of T cells? What do they recognize and bind? How many different kinds of receptors are on the surface of ONE T cell (careful, this might be a trick question)?

Answer 28

T Cell Receptors (TCRs) are protein complexes found on the surface of T cells or T lymphocytes responsible for recognizing antigens on foreign substances. Without TCRs, the immune system would not be able to successfully identify and fight infectious disease. T-cell receptors bind to certain antigens (proteins) found on abnormal cells, cancer cells, cells from other organisms, and cells infected with a virus or another microorganism. This interaction causes the T cells to attack these cells and helps the body fight infection, cancer, or other diseases. Also called TCR. There are two types of T cell receptor (TCR); alpha beta and gamma delta, both of which are composed of a heterodimer and associated with invariant CD3 complexes on the cell surface.

Question 29

Lymphocytes recognize a huge diversity of antigens; how do they achieve such diversity? How does VDJ recombination work?

Answer 29

Lymphocytes present receptors for antigen (Ag) recognition (TCR and BCR respectively) with different specificities on their surfaces. The genes that encode for these structures undergo a series of DNA recombinations, which provides them with immense phenotypic diversity. This process, termed V(D)J recombination, chooses a pair of segments, introduces double-strand breaks adjacent to each segment, deletes (or, in selected cases, inverts) the intervening DNA, and ligates the segments together

Question 30

What CD molecule is on the surface of TH cells? Describe three ways that TH cells are ‘helpers’.

Answer 30

CD is an abbreviation “for cluster of differentiation”. CD molecules are cell surface markers which are very useful for the identification and characterization of leukocytes and the different subpopulations of leukocytes. Helper T cells are arguably the most important cells in adaptive immunity, as they are required for almost all adaptive immune responses. They not only help activate B cells to secrete antibodies and macrophages to destroy ingested microbes, but they also help activate cytotoxic T cells to kill infected target cells.

Question 31

What CD molecule is on the surface of TC cells? How does a cytotoxic T-lymphocyte kill a virally infected cell? (Use the words “perforin”, “granzyme” and “apoptosis” in your answer.)

Answer 31

CD4 and CD8 co-receptors on the surface of T cells. Cytotoxic T cells (TC) express CD8, which recognizes class I MHC proteins, whereas helper T cells (TH) express CD4, which recognizes class II MHC proteins. Cytotoxic T cells kill their targets by programming them to undergo apoptosis (Fig. 8.35). When cytotoxic T cells are mixed with target cells and rapidly brought into contact by centrifugation, they can program antigen-specific target cells to die within 5 minutes, although death may take hours to become fully evident.

Question 32

Describe the B cell production and maturation process, including the locations and positive vs. negative selections.

Answer 32

B cell development starts in the bone marrow (BM) and continues in the spleen to final maturation. Developmental progression is guided by sequential events leading to assembly, expression, and signaling of the B cell antigen receptor (BCR). Both B and T cells undergo positive and negative selection in the primary lymphoid organs. Positive selection requires signaling through the antigen receptor for the cell to survive. Developing B cells are positively selected when the pre-B receptor binds its ligand.

Question 33

What is VDJ recombination, and how does it play a role in BCR diversity?

Answer 33

VDJ Recombination is a recombination of V, D, J segments into numerous combinations that makes up the variable regions of the recepeptor of lymphocytes. It plays a role in BCR diversity because through recombination, the BCR will theoretically have all the possible combination on its receptors to recognize any epitopes of antigens.

Question 34

What is T cell-independent B cell activation? How long is the effect? Are memory cells produced?

Answer 34

Activation of B cells without the cooperation of helper T cells is referred to as T cell-independent activation and occurs when BCRs interact with T-independent antigens. T-independent antigens (e.g., polysaccharide capsules, lipopolysaccharide) have repetitive epitope units within their structure, and this repetition allows for the cross-linkage of multiple BCRs, providing the first signal for activation. The T cell-independent response is short-lived and does not result in the production of memory B cells.

Question 35

What is T cell-independent B cell activation? How long is the effect? Are memory cells produced?

Answer 35

Activation of B cells without the cooperation of helper T cells is referred to as T cell-independent activation and occurs when BCRs interact with T-independent antigens. T-independent antigens (e.g., polysaccharide capsules, lipopolysaccharide) have repetitive epitope units within their structure, and this repetition allows for the cross-linkage of multiple BCRs, providing the first signal for activation. The T cell-independent response is short-lived and does not result in the production of memory B cells.

Question 36

What is T cell-dependent B cell activation? How long is the effect? Are memory cells produced? What is class switch recombination?

Answer 36

T cell-dependent B cell activation is a process in which B cell is activated by a helper T cell in order to produce antibodies against a specific antigen. This process involves the recognition of the antigen by B cell receptors and the subsequent presentation of the antigen to T cells. The T cells then activate the B cells through the release of cytokines and other signaling molecules, leading to the proliferation and differentiation of the B cells into plasma cells that produce antibodies. The effect of this process can last for weeks to months, and memory B cells are produced to provide long-term immunity to the antigen. Class switch recombination is a mechanism by which B cells switch the class of antibody they produce without changing the specificity for the antigen.

Question 37

What are primary and secondary responses? Compare the speed of reaction, the classes of antibodies produced, and the total amount of antibodies produced.

Answer 37

A primary immune response results in the generation of memory immune cells. A secondary immune response occurs as a result of a second exposure to an antigen. It is a much more rapid and sustained response due to the action of memory immune cells. Primary immune response 7-10 days, Secondary immune response 3-5 days The primary immune response is characterized by the appearance of neutralizing antibodies of the IgM class between days 4 and 7, several days before detection of IgG antibodies. The secondary antibody response is characterized in its first few days by the production of small amounts of IgM antibody and larger amounts of IgG antibody, with some IgA and IgE.

Question 38

Describe the four classes of immunity.

Answer 38

Innate Immunity: This is the first line of defense that our body uses to prevent infections. Innate immunity is non-specific, which means it responds the same way to all types of pathogens. The innate immune system includes physical barriers like the skin and mucous membranes, as well as cells like neutrophils and macrophages that can engulf and destroy pathogens. Adaptive Immunity: Also known as acquired immunity, this type of immunity is specific to a particular pathogen. It involves the activation of immune cells like T-cells and B-cells that can recognize and target a specific pathogen. Once the immune system has encountered a pathogen, it creates memory cells that can quickly recognize and respond to the same pathogen in the future. Passive Immunity: Passive immunity is acquired when antibodies produced by another organism are introduced into the body. This can occur naturally, such as when a mother passes antibodies to her baby during breastfeeding, or it can be artificially induced through the administration of antibodies, as in the case of immunoglobulin therapy. Immunological Tolerance: Immunological tolerance refers to the ability of the immune system to recognize and tolerate the body's own cells and tissues. Failure of this mechanism can lead to autoimmune diseases, where the immune system mistakenly attacks the body's own tissues. Immunological tolerance is established during embryonic development and is maintained throughout life.

Question 39

What is the difference between variolation and vaccination?

Answer 39

The main difference between variolation and vaccination is what form of the pathogen is exposed to the person. In variolation, a small amount of the live pathogen is exposed to the person in an attempt for the person's adaptive immune to develop defenses without causing the person to actually get severely sick. This is an outdated method now, and is no longer used. In vaccination, a weakened, inactivated, or dead version of the pathogen is used, or a component of the pathogen (such as the vaccine for Covid-19 which involves using a small portion of the genetic material that codes for surface protein of the virus) is used. Generally speaking, this is the standard practice in modernity in terms of creating herd immunity, and vaccines often require much testing, processing, manufacturing etc. before being introduced to the general public.

Question 40

What is a live, attenuated vaccine? What are some pros and cons?

Answer 40

A live, attenuated vaccine uses a weakened or modified form of the pathogen to stimulate an adaptive immune response without causing illness in the patient. Pros include: -Strong, long lasting immunity -mimics actual infection, meaning different strains of the pathogen may also be immunized against by just one vaccine -live, attenuated vaccines usually require fewer doses than other forms of vaccine Cons include: -potential risk of the pathogen reverting back to virulent form and causing disease -not advisable for people with compromised immune systems -requires careful storage and transportation to maintain efficacy

Question 41

What is an inactivated vaccine? What are some pros and cons?

Answer 41

An inactivated vaccine is a vaccine that uses the dead form of the pathogen or some inactivated version of it, meant to invoke an adaptive immune response without causing disease. Pros: -inactivated vaccines cannot cause disease -safer for immunocompromised patients (compared to live attenuated vaccines) -much more stable and easier to transport and store (compared to live attenuated vaccines) Cons: -long term immune response not as strong or robust as live attenuated vaccines -duration of immunity is shorter compared to live attenuated vaccines -booster shots will be needed to maintain immunity

Question 42

What is a subunit vaccine? What are some pros and cons?

Answer 42

Subunit vaccines expose the patient to only the key antigens of a pathogen, rather than whole cells or viruses. They are produced by chemically degrading a pathogen, as well as isolating its key antigens, or produce the key antigens through genetic engineering. conjugate vaccines are a type of subunit vaccine, consisting of a proteins conjugated to a capsule polysaccharide. They developed to enhance the efficacy of the vaccines against pathogens with polysaccharide capsules, granting greatly ability got phagocytosis. Children under the age of 2 do not respond effectively, specifically to conjugate, subunit vaccines. Because subunit vaccines have hand picked essential antigens, they have relatively low risk for causing side affects.

Question 43

What are the two polio vaccines? What are the pros and cons of each, and where are they available? Why has the US stopped using the live attenuated vaccine since 2000?

Answer 43

The two polio vaccines are the Salk and Sabin vaccine. The pros of the Salk vaccine are that it has a longer shelf life, it lead to infection of the disease, and it cant't cause an active it doesn't strict conditions for storage and transportation. The cons are that it has to be given by a medical professional, it isn't useful in controlling epidemics, it doesn't provide intestinal immunity, doesn't prevent reinfection and it is more difficult to manufacture and more expensive. The pros of the Sabin vaccine include prevention of reinfection, can be given orally, humoral and intestinal immunity, useful in controlling epidemics and cheaper/easier to manufacture. The cons are that it requires subzero storage temperatures, is damaged easily and it can infect cells. The United States uses the Salk vaccine, but the Sabin vaccine is useful in developing countries since it is given orally and doesn't require medical professionals to administer it. The U.S stopped using the live attenuated vaccine because it can possibly infect people who take it and become virulent.

Question 44

How long does it usually take for a new vaccine to go on market? How is vaccine safety monitored?

Answer 44

It usually takes at least a few years for a vaccine to be developed and go on market. Vaccine safety is monitored by loads of pre-clinical research, then clinical trials. The clinical trials examine a vaccines safety and efficacy. Following the testing, more people look at the data to determine whether it is fit to go onto market. Once it is on market, there are still institutions in place to monitor how the vaccine is "performing" within the population.

Question 45

What does the vaccine mandate achieve? Who does it aim to protect?

Answer 45

Vaccine mandates help prevent outbreaks of contagious diseases and contribute to the overall goal of achieving herd immunity by increasing vaccination rates through making certain vaccinations a condition of employment, school attendance, or participation in certain activities. This leads to a reduction in the spread of vaccine-preventable diseases, and helps to protect those who are not immunized or who are more susceptible.

Question 46

What are the signs and symptoms of measles? What are some complications that could lead to death?

Answer 46

The signs and symptoms can start with a high fever that begins within two weeks after the exposure. Runny nose, watery eyes and white spots inside the cheeks can develop at the initial stage. As the disease develops, a rash can start too on the face and upper neck, which can later spread out to the rest of the body. Some of the complications usually happen in immunocompromised patients, children under 5 and adults over 30. These complications include encephalitis, severe respiratory infections such as pneumonia, severe diarrhea that can lead to dehydration if not treated on time.

Question 47

What is the causative agent of measles, and what kind of genome does it have?

Answer 47

Measles virus (MeV) is the causative agent and it is a single-stranded RNA virus. It has an envelope and glycoproteins on the surface. The RNA genome is encapsulated by the N (nucleoprotein) protein. It also includes the H protein which helps the virus bind to the host cell and the F protein that plays a role in fusion, penetration and hemolysis. There is also the M protein that promotes virion assembly and the P protein that is a RNA polymerase cofactor. Here is an image of the virus.

Question 48

Do you know the viral life cycle? Do you know how proteins like H or F fit into the viral life cycle?

Answer 48

The virus life cycle could be divided into six steps: attachment, penetration, uncoating, gene expression and replication, assembly, and release. The viral capsid (blue) and genome (brown) are schematically drawn for the purpose of explanation. The nucleus is omitted for clarity.

Question 49

What kinds of host cells does MeV infect? What tissues/organs does the infection affect? How does it cause immune amnesia?

Answer 49

Measles virus (MeV) primarily infects and replicates in cells of the respiratory tract, such as epithelial cells and macrophages. However, once the virus enters the bloodstream, it can spread to other tissues and organs, including the lymphatic system, skin, and CNS. MeV causes immune amnesia by interfering with the immune system's ability to remember previously encountered pathogens. MeV cells can selectively target and destroy memory B and T cells, which are responsible for providing long-term protection against pathogens that the body has previously encountered. This occurs through the interaction between MeV proteins and host immune receptors, leading to apoptosis or death of the memory cells. As a result, individuals who have had measles may be at increased risk of other infections, even years after they have recovered from the disease.

Question 50

How is MeV transmitted? Why does the virus have a high reproduction number? When are infected individuals contagious?

Answer 50

MeV is transmitted through respiratory droplets produced by sneezing/coughing or direct contact with the nasal or throat secretions from an infected person. MeV is an extremely infectious disease. The virus can survive in the air for up to two hours which is why the reproduction number is high. Measles is most infection during the prodromal period and period of illness.

Question 51

What is the best prevention of measles? Why is measles making a comeback? Do you know the evidence for and against the notion that there is a link between the MMR vaccine and autism?

Answer 51

The best prevention of measles is to get vaccinated with the MMR vaccine. Measles is making a comeback because there has been an anti vaccination movement, with some parents who believe the vaccines can give their children autism or other dangerous side effects. With less people being vaccinated it lowers the heard immunity and allows the disease to spread to more people. There is no scientific evidence I could find the proves any connection between the MMR vaccine and autism. The CDC and all other scientific research I looked at shows that the vaccines do not cause autism. Here is a link to the CDC's page of autism and vaccines. https://www.cdc.gov/vaccinesafety/concerns/autism.htmlLinks to an external site.

Question 52

How is measles diagnosed and treated?

Answer 52

Measles can be diagnosed from the presence of Koplik's sport. Lab tests such as IFA, IgM titer, PCR, and viral culture are done. There is no effective treatments, but vaccination is the best way to prevent against measles. Koplik spots are small white inflamed spots on the inside of the cheek(s) of a patient who is experiencing the early stages of measles.

Question 53

What are the four types of hypersensitivities? What do A, B, C, D stand for?

Answer 53

The four hypersensitivity types include Types I, II, III, and IV. A, B, C, D is a mnemonic device associated with each hypersensitivity type. Type I is related to allergies, atopy, and anaphylaxis (A) Type II is related to antiBodies (B) Type III is related to the immune Complex(es). (C) Type IV is related to Delayed responses. (D)

Question 54

Describe the mechanisms of type I hypersensitivity.

Answer 54

Type 1 = Allergic Anaphylaxis and Atopy Type 1 hypersensitivity reaction involve IgE antibodies against a soluble antigen, which trigger mast cell degranulation. When a persons is exposed to an allergen, it can lead to rapid and immediate immune response which is called an allergy, this is classified as type 1 hyper sensitivity. The 1st exposure activates a primary IgE antibody response which sensitizes an individual to type 1 hyper sensitivity on the next exposure. The first exposure activates a strong TH2 cell response. Cytokines interleukin (IL)-4 and IL-13 from the TH2 cells activate B cells specific to the same allergen, resulting in clonal proliferation, differentiation into plasma cells, and antibody-class switch from production of IgM to production of IgE. The FC regions of the IgE antibodies then bind to receptors on the surface of mast cells through out the body. on 2nd exposure, allergens bind to IgE molecules and mast cells, crosslinking and within mast cells trigger, a reaction in which the contents of the granules in the mast cell are released into the extracellular environment. Preformed components that are released from granules include histamine, serotonin, and bradykinin degranulation.

Question 55

What are the roles of IgE, mast cells, basophils, histamine and cytokines in type I hypersensitivity?

Answer 55

Type I hypersensitivity is also known as an immediate reaction and involves immunoglobulin E (IgE) mediated release of antibodies against the soluble antigen. This results in mast cell degranulation and release of histamine and other inflammatory mediators.

Question 56

Distinguish between local (atopy) and systemic (anaphylaxis) type I hypersensitivities.

Answer 56

Local (atopy) type I hypersensitivity refers to localized allergic reactions. This type of reaction is commonly affecting specific tissues and organs like the skin, respiratory tract, and gastrointestinal tract. Atopic individuals usually experience symptoms in the affected area like redness, swelling, itching, or rash. Systemic (anaphylaxis) type I hypersensitivity usually involves a severe generalized allergic reaction that affects multiple organs and tissues and can be life-threatening if it is not treated right away. Systemic individual’s experiences severe symptoms like difficulty breathing, tightness in the chest, wheezing, swelling of the face and throat, and hives. Individuals who are usually allergic to certain foods like peanuts or shellfish, medications like penicillin, latex gloves or bee stings triggers this allergic reaction. Those who are allergic to certain allergens need immediate medical attention because these are life threatening if they aren’t given epinephrine treatments or any other type of measure.

Question 57

Which antibodies mediate type II hypersensitivity? Where are the antigens located?

Answer 57

Type II hypersensitivity is mediated by IgG and/or IgM antibodies The antigens that these antibodies bind to are cell surface antigens or matrix-associated antigens on basement membranes. These antibodies activate the complement system to lyse invading cells or participate in ADCC.

Question 58

Describe HDN. Know who’s at risk, cause and symptoms, as well as treatment.

Answer 58

Hemolytic disease of the newborn (HDN) — also called erythroblastosis fetalis — is a blood disorder that occurs when the blood types of a mother and baby are incompatible Who is affected by hemolytic disease of the newborn? Babies affected by HDN are usually in a mother's second or higher pregnancy, after she has become sensitized with a first baby. HDN due to Rh incompatibility is about three times more likely in Caucasian babies than African-American babies. Infants with HDN may be treated with: Feeding often and receiving extra fluids. Light therapy (phototherapy) using special blue lights to convert bilirubin into a form which is easier for the baby's body to get rid of.

Question 59

Which antibodies mediate type III hypersensitivity? Where are the antigens located?

Answer 59

Type III hypersensitivity is mediated by IgG and IgM antibodies. The antigens can be located in various places, including the circulation, basement membranes, and extracellular spaces of various tissues.

Question 60

Know examples of one local and one systemic type III hypersensitivities.

Answer 60

systemic type III: serum sickness caused by immune complexes involving no self proteins are deposited in various body sites resulting in a generalized systemic inflammatory response. Local type III: Arthus Reaction caused by soluble antigens that bind with IgG in a ration that results in the accumulation of antigen-antibody aggregates (Immune complexes).

Question 61

Why is type IV called ‘delayed response’? Which branch of adaptive immunity is involved?

Answer 61

The first three types are considered immediate hypersensitivity reactions because they occur within 24 hours. The fourth type is considered a delayed hypersensitivity reaction because it usually occurs more than 12 hours after exposure to the allergen, with a maximal reaction time between 48 and 72 hours. Cell mediated Know a local and a systemic example of type IV hypersensitivities systemic examples include contact dermatitis, poison ivy, tuberculin skin test, and certain drug reactions, such as allopurinol. Treatment options for Type IV hypersensitivity may include medications like corticosteroids and avoiding exposure to the triggering antigen.

Question 62

Autoimmune diseases are the development of hypersensitivity to your own cells. What are some possible causes?

Answer 62

The exact cause of autoimmune disorders is unknown. One theory is that some microorganisms (such as bacteria or viruses) or drugs may trigger changes that confuse the immune system. This may happen more often in people who have genes that make them more prone to autoimmune disorders.

Question 63

What is celiac disease? Which organ(s) does it mainly affect? What is a gluten-free diet and what does it achieve?

Answer 63

An immune reaction to eating gluten, a protein found in wheat, barley, and rye. Over time, the immune reaction to eating gluten creates inflammation that damages the small intestine's lining, leading to medical complications. It also prevents absorption of some nutrients (malabsorption). The classic symptom is diarrhea. Other symptoms include bloating, gas, fatigue, low blood count (anemia), and osteoporosis. Many people have no symptoms. The mainstay of treatment is a strict gluten-free diet that can help manage symptoms and promote intestinal healing.

Question 64

What are Graves and Hashimoto diseases? Which organ(s) does it mainly affect?

Answer 64

Both Graves' disease and Hashimoto's disease are autoimmune disorders that result when antibodies from your immune system begin to attack the thyroid. The differing antibodies have opposite effects on the gland, however. While Hashimoto's causes the thyroid to become underactive, Graves' makes it overactive.

Question 65

How do you think Graves and Hashimoto diseases are treated? Why do you think they might be hard to treat?

Answer 65

Medical management of Graves' and Hashimoto's is paramount, and in some cases, all that is needed. Expert surgery remains the best and most reliable treatment option to definitively cure both of these thyroid conditions.

Question 66

What is type I diabetes? Which organ(s) does it mainly affect? How does it affect the patient?

Answer 66

What is type 1 diabetes? Type 1 diabetes is a serious condition where your blood glucose (sugar) level is too high because your body can't make a hormone called insulin. This happens because your body attacks the cells in your pancreas that make the insulin, meaning you can't produce any at all.

Question 67

What is Addison disease? Which organ(s) does it mainly affect? How does it affect the patient?

Answer 67

Addison's disease is caused by damage to the adrenal glands. The adrenal glands sit just above the kidneys. As part of the endocrine system, they make hormones that affect almost every organ and tissue in the body. Damage to these glands results in too little of the hormone cortisol and, often, the hormone aldosterone.

Question 68

What is multiple sclerosis? What is the cause of MS?

Answer 68

MS is a condition that can affect the brain and the spinal cord, causing a wide range of potential symptoms, some of them mild and others can cause serious disability. Though there is no specific cause, it is said that in MS the immune system attacks the protective coat of the nerves called the myelin sheath. This damaging can mean in a slowing or disruption of the messages traveling along those nerves. There’s other factors like environmental or genetics or a combination that might be involved.

Question 69

What is myasthenia gravis and what causes it?

Answer 69

Antibodies—Myasthenia gravis is caused by an error in how nerve signals are transmitted to muscles. It occurs when communication between the nerve and muscle is interrupted at the neuromuscular junction—the place where nerve cells connect with the muscles they control.

Question 70

What are psoriasis and rheumatoid arthritis?

Answer 70

Psoriatic arthritis is a type of arthritis linked with psoriasis, a chronic skin and nail disease. Psoriasis causes red, scaly rashes and thick, pitted fingernails. Psoriatic arthritis is similar to rheumatoid arthritis (RA) in symptoms and joint swelling (inflammation). But it tends to affect fewer joints than RA.

Question 71

What is SLE / Lupus? What are some diagnostic tests?

Answer 71

Antinuclear Antibody Tests An antinuclear antibody (ANA) blood test measures the presence of antibodies that are directed against the body's cells, a sign of systemic lupus erythematosus. ANA is present in nearly everyone with active lupus.

Question 72

Rejection of the transplanted organ is actually a sign of a healthy immune system. Which branch of adaptive immunity is mainly involved?

Answer 72

Hyperacute rejection is usually caused by specific antibodies against the graft and occurs within minutes or hours after grafting. Acute rejection occurs days or weeks after transplantation and can be caused by specific lymphocytes in the recipient that recognize human leukocyte antigens in the tissue or organ grafted.

Question 73

Describe the 4 classes of grafts.

Answer 73

The four types of grafts are: (i) allograft Listen to pronunciation. (A-loh-graft) The transplant of an organ, tissue, or cells from one individual to another individual of the same species who is not an identical twin. (ii) autograft A patient's own tissue - an autograft - can often be used for a surgical reconstruction procedure. Autograft tissue is the safest and fastest-healing tissue that can be used. However, harvesting autograft tissue creates a second surgical site from which the patient must recover. (iii) xenograft The transplant of an organ, tissue, or cells to an individual of another species. (iv) isograft. Skin autograft (isograft) is a graft transferred from a donor to a recipient site in the same individual. Skin allograft (homograft) is a graft transplanted between genetically disparate individuals of the same species. Skin xenografts (heterografts) are grafts transplanted between individuals of different species.

Question 74

What is the main difference between primary and secondary immunodeficiency? What are the causes of primary immunodeficiency? What are the causes of secondary immunodeficiency?

Answer 74

Primary immunodeficiencies are a group of more than 400 rare, chronic disorders that impact the ability of the body to fight infection. Onset can occur in childhood or early adulthood. Secondary immunodeficiencies, by contrast, occur after an additional immune stress that the body experiences. Many primary immunodeficiency disorders are inherited — passed down from one or both parents. B cell (antibody) deficiencies. T cell deficiencies. Combination B and T cell deficiencies. Defective phagocytes. Complement deficiencies. Unknown (idiopathic) Secondary immunodeficiency (SID) occurs when the immune system is weakened by another treatment or illness. What causes secondary immunodeficiency? There are many potential causes of SID but the most common examples are blood or bone marrow disorders, drugs (medicines) and treatment for cancer.

Question 75

What are the main complications of B cell versus T cell deficiency?

Answer 75

Patients with B-cell disorders have decreased immunoglobulin levels (hypogammaglobulinemia), resulting in an increased incidence of early recurrent infections, which may ultimately lead to significant damage involving different organs, particularly the respiratory system.

Question 76

Where did HIV originate? How do scientists think the virus jumps species from chimpanzee to human? How did it spread to the other continents?

Answer 76

HIV infection in humans came from a type of chimpanzee in Central Africa. Studies show that HIV may have jumped from chimpanzees to humans as far back as the late 1800s. The chimpanzee version of the virus is called simian immunodeficiency virus. The SIV jump to humans is believed to have occurred through the practice of butchering chimpanzees and other nonhuman primates for food. This increased the chances for viral transmission because it placed humans in contact with the animals' blood. The virus spread may have spread from Kinshasa along infrastructure routes (roads, railways, and rivers) via migrants and the sex trade. In the 1960s, HIV spread from Africa to Haiti and the Caribbean when Haitian professionals in the colonial Democratic Republic of Congo returned home.

Question 77

How does HIV infection progress? Do you know the CD4 helper T cell count, viral load, and the symptoms of each stage? What are AIDS-defining illnesses?

Answer 77

The three stages of HIV infection are (1) acute HIV infection, (2) chronic HIV infection, and (3) acquired immunodeficiency syndrome (AIDS). There is no cure for HIV, but treatment with HIV medicines (called antiretroviral therapy or ART) can slow or prevent HIV from advancing from one stage to the next. Stage 1 (HIV infection): The CD4+ cell count is at least 500 cells per microlitre. Stage 2 (HIV infection): The CD4+ cell count is 350 to 499. Stage 3 (advanced HIV disease, or AHD): The CD4+ cell count is 200 to 349. Cytomegalovirus disease or CMV (other than liver, spleen, or nodes) Cytomegalovirus retinitis (with loss of vision) Encephalopathy, HIV related. Herpes simplex: chronic ulcer(s) (more than 1 month in duration); or bronchitis, pneumonitis, or esophagitis. Histoplasmosis, disseminated or extrapulmonary.

Question 78

What is the spike protein of HIV? What receptors does it bind?

Answer 78

to infect cells, the HIV protein envelope (Env) binds to the primary cellular receptor CD4 and then to a cellular coreceptor. This sequential binding triggers fusion of the viral and host cell membranes, initiating infection.

Question 79

What are the three enzymes the virus has? How do they function?

Answer 79

When the virus invades a CD4 cell, the cell becomes reprogrammed to create new copies of HIV. To do this, HIV needs the help of certain enzymes: reverse transcriptase, protease, and integrase. The major classes of HIV medications work by blocking these enzymes and preventing CD4 cells from turning into HIV replicators.

Question 80

Do you know the life cycle of HIV? Draw it out on.

Answer 80

What are the seven stages of the HIV life cycle? The seven stages of the HIV life cycle are: 1) binding, 2) fusion, 3) reverse transcription, 4) integration, 5) replication, 6) assembly, and 7) budding.

Question 81

What is the CCR5 delta 32 mutation, and how does it benefit people with this mutation?

Answer 81

The CCR5-delta 32 mutation in a sense locks "the door" which prevents HIV from entering into the cell. 1% of people descended from Northern Europeans, particularly Swedes, are immune to HIV infection.

Question 82

How is HIV transmitted? Do you know which areas of the world are more heavily affected by HIV infection?

Answer 82

How is HIV passed from one person to another? Most people get HIV through anal or vaginal sex, or sharing needles, syringes, or other drug injection equipment (for example, cookers). But there are powerful tools to help prevent HIV transmission. Sub-Saharan Africa,9 home to two-thirds of all people living with HIV globally, is the hardest hit region in the world, followed by Asia and the Pacific. Latin America as well as Eastern Europe and Central Asia are also heavily affected.

Question 83

How is HIV infection diagnosed and treated? Do you know what steps of the viral life cycle the drugs target? What is PrEP?

Answer 83

Blood tests are the most common way to diagnose the human immunodeficiency virus (HIV), the virus that causes acquired immunodeficiency syndrome (AIDS). These tests look for antibodies to the virus that are present in the blood of infected individuals. People exposed to the virus should get tested immediately. Pre-exposure prophylaxis is the use of medications to prevent the spread of disease in people who have not yet been exposed to a disease-causing agent, usually a virus. The term typically refers to the use of antiviral drugs as a strategy for the prevention of HIV/AIDS

Question 84

How are polyclonal antibodies produced? List out the steps.

Answer 84

Polyclonal antibodies is produced by: 1. Injecting the antigen into the rabbit. 2. Antigen activates the B cells. 3. The plasma B cell produces polyclonal antibodies. 4. Obtaining antiserum from the rabbit containing polyclonal antibodies.

Question 85

What are the pros and cons of polyclonal Ab?

Answer 85

Advantages: Inexpensive and relatively quick to produce (+/- 3 months). Higher overall antibody affinity against the antigen due to the recognition of multiple epitopes. Have a high sensitivity for detecting low-quantity proteins. High ability to capture the target protein (recommended as the capture antibody in a sandwich ELISA). Antibody affinity results in quicker binding to the target antigen (recommended for assays that require quick capture of the protein; e.g., IP or ChIP). Superior for use in detecting a native protein. Easy to couple with antibody labels and rather unlikely to affect binding capability. Disadvantages: Batch-to-batch variability as produced in different animals at different times. High chance of cross-reactivity due to a recognition of multiple epitopes (affinity purified antibodies display a minimum cross-reactivity). Polyclonal antibody production involves the repeated immunization of an animal with a desired antigen. Animals such as rabbits, goats, and sheep are generally used for polyclonal antibody production, as they are relatively easy to handle for immunization and bleeding purposes.

Question 86

How are monoclonal antibodies produced? List out the steps.

Answer 86

Antigen selection: The first step in producing monoclonal antibodies is to select the antigen or target molecule that the antibody will bind to. The antigen could be a protein, a cell surface receptor, or any other molecule that is involved in the disease process. Immunization: To produce monoclonal antibodies, animals such as mice or rats are injected with the chosen antigen. This stimulates their immune system to produce a wide variety of antibodies that can recognize and bind to the antigen. Harvesting of B-cells: After the animal has produced a sufficient amount of antibodies, B-cells (a type of white blood cell that produces antibodies) are extracted from the animal's spleen or lymph nodes. Fusion of B-cells with immortalized cells: The B-cells are then fused with immortalized cells called myeloma cells to create hybridoma cells. These hybridoma cells can produce antibodies indefinitely and are used to generate monoclonal antibodies. Screening of hybridoma cells: The hybridoma cells are screened to identify those that produce antibodies that bind specifically to the target antigen. This is typically done using an enzyme-linked immunosorbent assay (ELISA). Cloning of hybridoma cells: The hybridoma cells that produce antibodies that bind to the target antigen are then cloned to create a population of identical cells that produce the same monoclonal antibody.

Question 87

What are the pros and cons of monoclonal Ab? What are they mostly used for?

Answer 87

Despite their many advantages, a drawback of monoclonal antibodies is that they are more time-consuming and expensive to produce than polyclonals. If a monoclonal has not yet been developed, researchers may consider using an existing polyclonal antibody, then switching to a monoclonal if one becomes available. Monoclonal antibodies are being used in the diagnosis and treatment of many diseases, including some types of cancer. They can be used alone or to carry drugs, toxins, or radioactive substances directly to cancer cells.

Question 88

What is humanized mAb? Explain why it is necessary.

Answer 88

One common method for production of monoclonal antibodies is through use of mouse cells, However since the immune system will recognized the antibodies as foreign and neutralize them, it is necessary to create humanized monoclonal antibodies for clinical use in humans. You can reduce the risk of this problem by genetically engineering the antibody of the mouse's B cells, The variable regions of the mouse light and heavy chain genes are ligated to human constant regions, and the chimeric gene is then transferred into a host cell. This allows production of a mAb that is mostly "human" with only the antigen-binding site being of mouse origin. mAbs are able to recognize a single epitope on an antigen and are able to produce large amounts of specific antibodies, which adds to their importance.

Question 89

How does Western blot work? How does agglutination assays work?

Answer 89

Western blot works by separating the proteins in the sample based on their size using gel electrophoresis. Then they are transferred onto a membrane in turn probing the membrane with specific antibodies. Agglutination assays work by causing visible clumping or aggregation of particles when they bind to their respective targets.

Question 90

What are EIAs and ELISAs? How does immunofluorescence staining work?

Answer 90

EIA (enzyme immunoassay) uses antibodies to detect the presence of antigens. ELISA (enzyme-linked immunosorbent assay) is a widely used EIA. In direct ELISA, antigens are immobilized in the well of a microtiter plate. In indirect ELISA, it quantifies antigen-specific antibody rather than antigen. Indirect ELISA is used to detect antibodies against pathogens such as HIV. Immunofluorescence staining is a technique that uses antibodies and fluorescence imaging to visualize biomolecules within fixed cell or tissue samples.

Question 91

Distinguish phenotypic, genotypic and immunological methods for diagnosis. Know at least two examples for each.

Answer 91

Phenotypic methods use observed properties like metabolic and morphological differences in species to identify microorganisms. For example examining a gram stain with a microscope or performing a catalase test on a bacteria. Genotypic methods observe an organisms genetic material like the DNA and RNA sequences. Two examples include a PCR test and PFGE. Immunological methods use antibodies to observe and detect for antigens to identify a virus. Two examples are EIAs and ELISAs.

Question 92

What do biochemical tests include? What are some limitations of phenotypic methods?

Answer 92

Biochemical tests include tests such as Methyl Red, glucose fermentation, phenylalanine deaminase, and starch hydrolysis. Many other biochemical tests are available. However, some limitations exist due to the reliability of certain tests, such as the starch hydrolysis test producing false negatives, and the citrate test sometimes producing false negatives as well.

Question 93

What are the advantages and limitations of genotypic methods?

Answer 93

Advantages of genotypic methods: High specificity: Genotypic methods are highly specific and can detect very small amounts of target genetic material. This makes them very useful in detecting and identifying specific pathogens or genetic mutations. Rapid detection: Some genotypic methods, such as polymerase chain reaction (PCR), can produce results in a matter of hours, making them very useful for rapid diagnosis and treatment of infectious diseases. High sensitivity: Genotypic methods can detect very low levels of genetic material, which makes them very useful for detecting infections in patients with low levels of pathogen exposure. Non-invasive: Many genotypic methods, such as those that use blood or saliva samples, are non-invasive and do not require invasive procedures like biopsies. Limitations of genotypic methods: False negatives: Genotypic methods can sometimes produce false negative results, especially if the pathogen load is very low or the sample collection and processing are not done correctly. Cost: Genotypic methods can be expensive, especially when compared to traditional diagnostic methods. Complexity: Some genotypic methods require specialized training and equipment, which can be challenging to access in some settings. Limited information: Genotypic methods can only provide information about the genetic material they are designed to detect and cannot provide information about other aspects of the organism or disease.

Question 94

Which of the following constantly sheds dead cells along with any microbes that may be attached to those cells?

Answer 94

epidermis

Question 95

Proteins found in blood plasma are involved in the nonspecific innate immune response and include which of the following? Mark all that apply.

Answer 95

Cytokines Complement proteins Acute-phase proteins

Question 96

White blood cells are also referred to as which of the following?

Answer 96

leukocytes

Question 97

_____________ are similar to basophils, but reside in tissues rather than circulating in the blood.

Answer 97

Mast cells

Question 98

The ________ is the part of the body responsible for regulating body temperature.

Answer 98

hypothalamus

Question 99

B cells mature in the _______ and are responsible for _______ immunity.

Answer 99

bone marrow/humoral

Question 100

What is involved in the process of thymic selection? Mark all that apply.

Answer 100

Apoptosis of thymocytes that will interact with self-antigens. Positive selection of thymocytes that will interact appropriately with MHC molecules.

Question 101

The coordination between B cells and helper T cells that are specific to the same antigen is referred to as ___________.

Answer 101

linked recognition

Question 102

Match each type of vaccine with the corresponding example.

Answer 102

live attenuated vaccine, weakened influenza virions that can only replicate in slightly lower temperatures of the nasal are sprayed into the nose. They do not cause serious flu symptoms, but still produce an active infection that induces a protective adaptive immune response toxoid vaccine, tetanus toxic molecules are harvested and chemically treated to render them harmless, they are then injected into a patient's arm inactivated vaccine, influenza virus particles grown in chicken eggs are harvested and chemically treated to render them non-infectious. These immunogenic particles are then purified, packaged and administered as an injection subunit vaccine, the gene for hepatitis B virus surface antigen is injected into a yeast genome. The modified yeast is grown and the virus protein is produced, harvested, purified, and used in a vaccine

Question 103

An example of natural passive immunity would be

Answer 103

a fetus acquiring maternal IgG to the chickenpox virus across the placenta.

Question 104

Antibodies involved in type I hypersensitivities are of the ________ class.

Answer 104

IgE

Question 105

Characterize the diseases as organ-specific or systemic autoimmune disorders.

Answer 105

Celiac disease, organ-specific MS, systemic Hashimoto thyroiditis, organ-specific Myasthenia gravis, systemic Type I diabetes, organ-specific

Question 106

For a transplant to have the best chances of avoiding rejection, the genes coding for the ________ molecules should be closely matched between donor and recipient.

Answer 106

MHC

Question 107

Unlike primary immunodeficiencies, which have a genetic basis, secondary immunodeficiencies are often ___________ if the underlying cause is resolved.

Answer 107

reversible

Question 108

What is the most common animal used in production of monoclonal antibodies?

Answer 108

mouse

Question 109

Compare polyclonal Ab with monoclonal Ab.

Answer 109

Produce large quantities of specific Ab, monoclonal Ab Produce large quantities of nonspecific Abs, Polyclonal Ab Inexpensive to produce, Polyclonal Ab Expensive to produce, monoclonal Ab

Question 110

Soluble antigens are detected in this type of test.

Answer 110

Precipitation

Question 111

In a direct fluorescent antibody test, which of the following would we most likely be looking for using a fluorescently-labeled mAb?

Answer 111

bacteria in a patient sample

Question 112

The reason that MeV can hijack immune cells to help it spread is because it uses membrane _________ instead of ________ to get into host cells. Instead of being destroyed by enzymes released from lysosomes, it replicates in the ________ of the host cell. When the mature virions are released from the host cell, they lyse the host cell. When ________ T and B cells are infected, they are destroyed, causing immune amnesia.

Answer 112

The reason that MeV can hijack immune cells to help it spread is because it uses membrane fusion instead of endocytosis to get into host cells. Instead of being destroyed by enzymes released from lysosomes, it replicates in the cytoplasm of the host cell. When the mature virions are released from the host cell, they lyse the host cell. When memory T and B cells are infected, they are destroyed, causing immune amnesia.

Question 113

Compare and contrast Andrew Wakefield's 1998 study and the 2019 Danish study on the link between the MMR vaccine and autism.

Answer 113

Sample # of 12, wakefield study Sample # of > 657,000, danish study No control group, wakefield study Have control group, danish study No statistics, wakefield study Have statistics, danish study

Question 114

Match the steps of HIV life cycle with the events.

Answer 114

Adsorption, HIV gp120 binds to receptor such as CD4 Uncoating, release RNA and enzymes into the host cell Integration, Integrase cuts open host genome and inserts viral dsDNA Budding, release of new virions from the host cell

Question 115

Which of the following represents protective mechanism of the skin? Check all that apply.

Answer 115

Keratin makes the skin tough and water-proof Fatty acid creates a dry, salty, acidic environment hostile to microbes Epidermal layer cells are tightly connected Top layers of dead cells shredding

Question 116

________ is the fluid portion of a blood sample that has been drawn in the presence of an anticoagulant compound.

Answer 116

Plasma

Question 117

PMNs are another name for:

Answer 117

neutrophils

Question 118

Which of the following is a way for phagocytes to destroy pathogens? Check all that apply.

Answer 118

reactive nitrogen compounds reactive oxygen species microcidal defensins digestive enzymes

Question 119

Phagocytic cells contain ____________ capable of recognizing various pathogen-associated molecular patterns.

Answer 119

Pattern Recognition Receptors

Question 120

Heat and redness, or ________, occur when the small blood vessels in an inflamed area dilate (open up), bringing more blood much closer to the surface of the skin.

Answer 120

erythema

Question 121

Which process involves antibodies cross-linking cells or particles into large aggregates?

Answer 121

agglutination

Question 122

A single antigen molecule may be composed of many individual ________.

Answer 122

epitopes

Question 123

Which type of antigen-presenting molecule is found on all nucleated cells?

Answer 123

MHC I

Question 124

MHC I molecules present: Check all that apply.

Answer 124

processed foreign antigens from proteasomes. processed self-antigens from proteasomes.

Question 125

Cell surface glycoproteins that can be used to identify and distinguish between the various types of white blood cells are called ______________.

Answer 125

cluster of differentiation molecules

Question 126

What is a superantigen?

Answer 126

a protein that activates T cells in a nonspecific and uncontrolled manner

Question 127

Which of the following would be a BCR?

Answer 127

IgD

Question 128

Which part of the antibody molecule determines what epitope it binds to?

Answer 128

the two arms of the Y

Question 129

Which part of the antibody molecule determines what epitope it binds to?

Answer 129

the two arms of the Y

Question 130

A patient gets a cold, and recovers a few days later. The patient's classmates come down with the same cold roughly a week later, but the original patient does not get the same cold again. This is an example of:

Answer 130

Natural active immunity

Question 131

A(n) ___________ pathogen is in a weakened state; it is still capable of stimulating an immune response but does not cause a disease.

Answer 131

attenuated

Question 132

Inflammatory molecules are released by mast cells in type I hypersensitivities; type II hypersensitivities, however, are characterized by which of the following?

Answer 132

cell lysis (cytotoxicity)

Question 133

Which of the following would be most likely to exhibit an allergic response in a sensitive individual?

Answer 133

Ronnie is petting a cat for only the second time in her life.

Question 134

Characterize the diseases as organ-specific or systemic autoimmune disorders.

Answer 134

Addison disease, organ specific Psoriasis, systemic SLE, systemic Graves disease, organ specific RA, systemic

Question 135

In _______________, antigen-presenting cells in the donated bone marrow may see the host cells as non-self and once activated, the donor's T cells attack the recipient's cells.

Answer 135

Graft-vs-Host disease

Question 136

All but which one of the following are examples of secondary immunodeficiencies?

Answer 136

chronic granulomatous disease

Question 137

The property of a test to detect even small amounts of antibodies or antigens that are test targets is ________.

Answer 137

sensitivity

Question 138

What is the most common reason that prevents monoclonal antibodies from being widely used? Check all that apply.

Answer 138

Costly production Long production time

Question 139

Which statement is correct for the cross match test?

Answer 139

Can be used to quickly test the compatibility of a donor's blood test for transfusion

Question 140

In an enzyme immunoassay, the enzyme:

Answer 140

is bound to the constant region of the secondary antibody.

Question 141

This is the ____ form / stage of the parasite.

Answer 141

ring

Question 142

The disease that this parasite causes is:

Answer 142

malaria

Question 143

How does sickle hemoglobin differ from normal hemoglobin? Check all that apply.

Answer 143

Sickle hemoglobin have a tendency to form aggregate Sickle hemoglobin can stretch the RBCs into sickled shape Sickle hemoglobin are more hydrophobic

Question 144

Arrange the sites of MeV infection in the correct order.

Answer 144

URT epithelial cells and APCs Regional lymph nodes Bloodstream Skin, spleen, thymus, lungs, liver, and kidneys

Question 145

What samples should be taken for measles lab tests? Check all that apply.

Answer 145

Blood Throat swab

Question 146

Which of the following is NOT a characteristics of HIV?

Answer 146

DNA genome

Question 147

Match the phases of HIV infection with the descriptions.

Answer 147

High viral load and high T cell count, acute phase Low viral load, chronic phase High viral load and low T cell count, AIDS

Question 148

What does having the CCR5 delta 32 mutation reduce the chance of getting HIV infection?

Answer 148

CCR5 is the coreceptor on T cells that helps HIV gp120 binding to CD4

Question 149

Which of the following contributed to the early spread of HIV? Check all that apply.

Answer 149

Blood transfusion contamination Urban sex trade Railway building making traveling easier Re-use of needles in clinics

Question 150

Disruption of the _________________ by the damaging effects of smoking or diseases such as cystic fibrosis can lead to increased colonization of bacteria in the lower respiratory tract and frequent infections.

Answer 150

mucociliary escalator

Question 151

The term __________ refers to the coating of a pathogen by a chemical substance that allows phagocytic cells to recognize, engulf, and destroy it more easily.

Answer 151

opsonization

Question 152

Match each cell type with its description.

Answer 152

Basophil, stains with basic dye methylene blue, has large amount of histamine in granules, and facilitates allergic responses and inflammation Eosinophil, stains with acidic dye eosin, has histamine and major basic proteins in granules, and facilitates response to protozoa and helminths natural killer cell, recognizes abnormal cells, binds to them, and releases perforin and granzyme molecules, which include apoptosis Macrophage, large agranular phagocyte that resides in tissues such as the brain or lungs

Question 153

_____________ are similar to basophils, but reside in tissues rather than circulating in the blood.

Answer 153

Mast cells

Question 154

________, also known as diapedesis, refers to the exit from the bloodstream of neutrophils and other circulating leukocytes.

Answer 154

Extravasation

Question 155

To reach pathogens located in infected tissue, leukocytes must pass through the walls of small capillary blood vessels within tissues which is a process called _________. Mark any that apply.

Answer 155

extravasation diapedesis

Question 156

Which type of inflammation occurs at the site of an injury or infection?

Answer 156

acute

Question 157

A(n) ________ is a walled-off area of infected tissue that exhibits chronic inflammation.

Answer 157

granulomas

Question 158

The secondary response to an antigen is _______ and _______ when compared to the primary response.

Answer 158

faster/higher

Question 159

Acquired specific immunity involves the response of

Answer 159

B and T lymphocytes.

Question 160

Which type of antigen-presenting molecule is found only on macrophages, dendritic cells, and B cells?

Answer 160

MHC II

Question 161

MHC molecules are used for antigen ________ to T cells.

Answer 161

presentation

Question 162

Order the steps of helper T cell activation in the correct order.

Answer 162

1 TCR recognition of the specific foreign epitope presented with the MHC II antigen binding cleft 2 the MHC II - TCR is anchored ensuring that the T cell know self from non-self 3 the APC and T cell secrete cytokines that activate the helper T cell 4 T helper cell undergoes clonal expansion

Question 163

Which of the following apply to cytotoxic T cells? Mark all that apply.

Answer 163

APCs or infected nucleated cells presenting antigens associated with MHC I Destroy cells infected with intracellular pathogens CD8

Question 164

How long does the primary response lag period last?

Answer 164

10 days

Question 165

Which cells produce specific antibodies?

Answer 165

plasma cells

Question 166

Who is credited at ushering in the modern era of vaccinations?

Answer 166

Edward Jenner

Question 167

The term that describes a phenomenon in which a certain percentage of the population is vaccinated, making it impossible for the microbe to circulate is:

Answer 167

Herd immunity

Question 168

A person who is blood type AB would have IgM hemagglutinin antibodies against type ________ red blood cells in their plasma.

Answer 168

neither A nor B

Question 169

A person who is blood type A would have IgM hemagglutinin antibodies against type ________ red blood cells in their plasma.

Answer 169

B

Question 170

Which of the following is an example of an organ-specific autoimmune disease?

Answer 170

Addison disease

Question 171

Which of the following is an example of a systemic autoimmune disease?

Answer 171

myasthenia gravis

Question 172

Match the transplant with its description.

Answer 172

Autograft, from self to self Isograft, from identical twin to twin Xenograft, from animal to human Allograft, from one human to another

Question 173

Match the immunodeficiency to its correct category.

Answer 173

Selective IgA deficiency, humoral SCID, both X-linked agammaglobulinemia, humoral DiGeorge syndrome, cell-mediated

Question 174

What is the total strength of all interactions in an antibody-antigen complex known as?

Answer 174

Avidity

Question 175

The property of a test to detect only a certain antibody or antigen, and not to react with any others is ________.

Answer 175

specificity

Question 176

Which of the following uses red blood cells as an indicator?

Answer 176

Hemagglutination

Question 177

Which assay is great for visualization of bacteria that might be difficult to isolate from a patient's samples, by allowing fluorescent antibodies to detect the bacteria on a microscope slide?

Answer 177

Direct fluorescent

Question 178

Match the descriptions with the individual's genotype.

Answer 178

High risk of malaria, wild type individual (AA) Have only normal A form and no problem carrying oxygen, wild type individual (AA) Low risk of malaria but has a painful disease, Sickle cell anemia patients (SS) Have only abnormal S form, defective in carrying oxygen, Sickle cell anemia patients (SS) Low risk of malaria and no disease, Sickle cell carriers (AS) No problem with oxygen carrying except in low oxygen areas, Sickle cell carriers (AS) Have some A form and some S form, Sickle cell carriers (AS)

Question 179

Which of the following is the insect vector for malaria?

Answer 179

Anopheles mosquito

Question 180

Most of the specific signs and symptoms of measles appear during the ____ week after exposure.

Answer 180

Second

Question 181

How is measles transmitted? Check all that apply.

Answer 181

Indirect airborne transmission Direct contact with droplets

Question 182

At what stage of the disease are someone with an active measles infection contagious? Check all that apply.

Answer 182

Period of illness Prodromal period

Question 183

WHO declares vaccine hesitancy one of the ten leading threats to global health. Which of the following contributes to vaccine hesitancy in many people? Check all that apply.

Answer 183

People who cannot see the benefits of smallpox or polio vaccines because the successful vaccine programs eradicated the diseases in the US People who do not trust scientists and trust the information they get from the internet instead Well-intentioned parents who want to protect their children from harmful side effects of vaccines People who believe that MMR vaccines cause their children to develop autism

Question 184

Match the phases of HIV infection with the descriptions.

Answer 184

CD4+ helper T cell count > 500, acute phase CD4+ helper T cell count 200-499, chronic phase CD4+ helper T cell count < 200, aids

Question 185

Match the steps of HIV life cycle with the events.

Answer 185

Entry, HIV enter host cell through membrane fusion or endocytosis Reverse transcription, reverse transcriptase converts viral RNA to cDNA Biosynthesis, active protein and RNA synthesis Assembly, RNA and proteins assemble into new virion

Question 186

Which of the following contributed to the early spread of HIV? Check all that apply.

Answer 186

Blood transfusion contamination Reuse of needles in clinics Urban sex trade Railway building making traveling easier

Question 187

Why is the PCR test not used for initial screening of HIV?

Answer 187

Because it is too expensive