depth study

Question 1

define leucocyte

Answer 1

white blood cells which form part of the body’s immune system, help fight infection and other diseases

Question 2

define monocyte

Answer 2

an immune cell which becomes a macrophage or dendritic cell

Question 3

define macrophage

Answer 3

phagocytose pathogen and secrete pro-inflammatory mediators (long-life cells)

Question 4

define dendritic cells

Answer 4

found in tissues, boosts immune responses by showing antigens on its surface to lymphocytes to regulate adaptive immune response

Question 5

define neutrophils

Answer 5

first immune cells to respond, travel to site of infection where microorganisms are destroyed through ingestion and releasing of enzymes, (short lived cells)

Question 6

define Natural Killer cells

Answer 6

lymphocytes which recognise virally-infected cells as non-self via their detection of MHC complexes- able to kill tumour cells without prior activation (in contrast to cytotoxic T cells)

Question 7

what are CD4T cells also called?

Answer 7

“helper” cells

Question 8

What do CD4T cells do?

Answer 8

helper cells do not neutralise infections but rather trigger the body’s response to infections by stimulating other immune cells such as macrophages and B lymphocytes to fight infection

Question 9

what are CD8T cells also known as?

Answer 9

cytotoxic T lymphocytes

Question 10

What is the function of CD8T cells?

Answer 10

secrete cytokines which have anti-tumour and anti-viral microbial effects which ultimately result in apoptosis of the target cell

Question 11

what is the function of interleukins?

Answer 11

interleukins are a group of proteins made by leukocytes which regulate immune responses by modulating growth, differentiation and activation during inflammatory and immune responses.

Question 12

What does D.I.C stand for? What type of condition is it?

Answer 12

Disseminated Intravascular Coagulation; a rare but serious condition that causes abnormal blood clotting throughout the body’s blood vessels - proteins that control blood clotting become overactive

Question 13

What does A.R.D.S stand for? What type of condition is it?

Answer 13

Acute respiratory distress syndrome; a life threatening lung injury that allows fluid to leak into the lungs, occurs when alveoli fill up with fluid, keeping your lungs from filling up with air (less oxygen reaches your bloodstream, depriving your organs of the oxygen they need to function)

Question 14

what is anaemia?

Answer 14

not having enough healthy red blood cells to carry oxygen to the body’s tissues

Question 15

what is a cytokine storm?

Answer 15

a life-threatening systemic inflammatory syndrome involving elevated levels of circulating cytokines and immune cell hyper-activation - this could lead to multi-organ failure and death

Question 16

how can covid-19 trigger a cytokine storm?

Answer 16

SARS-CoV-2, the causative agent of COVID-19, attacks the immune system causing an exaggerated and uncontrolled release of cytokines which lead to anaemia or ARDS and ultimately death

Question 17

how can a cytokine storm lead to death?

Answer 17

patients can develop ARDS as a result of acute lung damage followed by multi-organ failure and resulting in death

Question 18

how do antiviral drugs work?

Answer 18

antivirals block receptors so viruses can’t bind to and enter healthy cells, boost the immune system to help it fight off a viral infection, lower the viral load (amount of active virus) in the body

Question 19

why do viruses mutate?

Answer 19

due to the high rate of replication, viruses are more susceptible to genetic mutations. Over time, these genetic copying errors can lead to alterations in the virus’ surface proteins or antigens which our immune system use to recognise and fight the virus

Question 20

why does virus mutation pose a problem for antiviral drugs?

Answer 20

• antiviral drug resistance
• increasing concern in immunocompromised patient populations, where prolonged drug exposure can lead to the selection of resistant strains
• drugs which were originally effective will no longer be effective

Question 21

how do antiviral drug manufacturers overcome the issue of viral mutation?

Answer 21

continuous surveillance, targeting conserved regions, combination therapies (consist of multiple antiviral agents with different mechanisms of action, reduces the likelihood of viral resistance), rational drug design (design drugs which bind to regions less likely to mutate), collaboration and research

Question 22

why are viral genomes mapped?

Answer 22

to compare the viruses around now to those that were around in the past - these sequences can be used to help them decide what to include in the vaccines

Question 23

what viral diseases have antiviral drugs?

Answer 23

Influenza, Hepatitis B and C, HIV

Question 24

what are the two main antiviral drugs used in Australia?

Answer 24

Paxlovid and Lagevrio

Question 25

what is the link between anti-RNA polymerase and protein synthesis?

Answer 25

Anti-RNA polymerase disrupts the translation of the virus' RNA in order to stop it from effectively replicating

Question 26

does SARS-CoV 2 contain DNA or RNA?

Answer 26

contains single-stranded genomic RNA

Question 27

are viruses with DNA or RNA more likely to mutate?

Answer 27

RNA - the higher mutation rates of RNA viruses can explained because RNA dependent RNA polymerases which replicate their genomes do not have a proofreading ability (unlike DNA polymerases) and are thus unable to correct mistakes during replication

Question 28

how may variants of COVID have been genome mapped to date?

Answer 28

Variants such as the alpha, beta, gamma and delta variant have been genome mapped, however new variants are constantly emerging

Question 29

What is an antibiotic?

Answer 29

Antibiotics are medicines that fight infections caused by bacteria in humans and animals by either killing the bacteria or making it difficult for the bacteria to grow and multiply.

Question 30

how do quinolones work as an antibiotic?

Answer 30

directly kill bacterial cells. Produce double-stranded breaks in the bacterial chromosome. It inhibits the DNA synthesis of bacteria by disrupting the bacterial topoisomerase type II; inhibiting the catalytic activity of DNA gyrase and topoisomerase IV (these two enzymes are critical bacterial enzymes that regulate the chromosomal supercoiling required for DNA synthesis)

Question 31

how do macrolides work as an antibiotic?

Answer 31

inhibit protein synthesis by targeting the bacterial ribosome. They do not kill bacteria, rather inhibit or suppress bacterial growth. Binds to the bacterial ribosomal subunit causing the cessation of bacterial protein synthesis. Interfere with the formation of long polypeptides and cause a premature detachment of incomplete peptide chains

Question 32

how to streptogramins act as an antibiotic?

Answer 32

interfere with the formation of long polypeptides and cause a premature detachment of incomplete peptide chains. Inhibit bacterial protein synthesis by binding sequentially to a ribosomal subunit.

Question 33

How effective are antibiotics as a treatment strategy for the control of infectious diseases?

Answer 33

They are effective at killing bacteria, however as a treatment strategy for controlling infectious disease their effectiveness is limited due to increasing resistance of bacteria to antibiotics This is due to the drug selection pressure, which leads to the survival of a resistant bacterial population or induces antibiotic resistance mechanisms This could lead to an incredibly resistant strain of bacteria which would be incredibly difficult to contain and control

Question 34

what is an antibody?

Answer 34

an antibody is formed for self-defence against antigens - detects harmful substances called antigens, bind to them and flag them for destruction Y-shaped, formed of four peptide chains

Question 35

Which antibodies are thought to be a treatment for COVID-19?

Answer 35

IgG, IgE, IgD, IgM, IgA

Question 36

why are there more COVID deaths in some countries than others?

Answer 36

Lack of adequate health sector infrastructure E.g. not enough health workers, doctors Covid 19 death toll is 4 times higher in low-income countries than high-income countries Not economically equipped to buy vaccines – cannot afford many vaccines Each country has a unique health care system and combat the pandemic with varying containment and mitigation strategies → some may be more effective than others

Question 37

what is immunological memory?

Answer 37

immunological memory is when memory B and T cells generated from first infection with a pathogen can mount a more rapid and effective immune response upon reinfection

Question 38

What are naive B cells activated by?

Answer 38

T-cells

Question 39

where to B-cells move to proliferate upon activation?

Answer 39

lymphoid organs such as the spleen and lymph nodes

Question 40

how do memory B-cells activate effector T-cells?

Answer 40

by presenting antigens on MHC-II molecules

Question 41

why are memory cells quicker to proliferate?

Answer 41

as they do not require continual interaction with antigen or T-cells to survive (as they have already undergone class switching and affinity maturation) they can divide faster and produce higher affinity antibodies such as IgG in response to antigens

Question 42

What is the difference between vaccination and immunisation?

Answer 42

Immunisation = the process of becoming immune to a disease as a result of a vaccine. Vaccination = when you receive a vaccine either by a needle or drops in the mouth. Vaccination is the term used for getting a vaccine – e.g. having the injection or taking an oral dose Immunisation refers to the process of both getting the vaccine and becoming immune to the disease following vaccination.

Question 43

What vaccines are currently used in Australia for Covid 19?

Answer 43

Pfizer, Oxford, Moderna, Novavax

Question 44

how are cytotoxic cells activated?

Answer 44

the CD8 receptor on the cell interacts with the MHC Class 1 molecules of other cells- if the cell is found to be non-self then the CD8T cells are activated