Lecture 3: Immunology & Vaccination

Question 1

What is the difference between an Antigen (Ag) and antigenicity?

Answer 1

Antigen: A part of an organism or substance that is recognized by the immune system as NON-self (often a cell-surface protein or sugar)
Antigenicity: Ability to stimulate immune response, an organism molecule can have many antigens of variable

Question 2

TRUE OR FALSE: The immune system has 2 types of immunity Active and Passive

Answer 2

TRUE: Active immunity is important in all animals and can be further separated into Non-specific and specific immunity.

Passive immunity is pre-formed antibody acquired from an outside source (colostrum or medical treatment: hyper-immune serum). Is has a short half life of approx 21 days. Maternal anti bodies considered gone by 6 months in calves and unknown in piglets. **have to be cautious with protection vs. interference with vaccination

Question 3

TRUE OR FASLE: Timing doesn’t matter when giving vaccinations to you animals

Answer 3

FALSE: Protection vs interference with vaccination is important because if you vaccinate when in passive immunity is high that would neutralize the vaccine since the immune system will fight off vaccine so it won’t be affective in the future.

Question 4

What are the physical barriers in the innate or non-specific defences? Explain

Answer 4

-Skin, hoof, hair, muscous membrane. Protects from trauma, pressure and cold/heat. Skin is the first line of defence.
-Mucus: in the respiratory tracts mechanically trap particles which facilitates removal
-Cilia (small hairs): In trachea and bronchi- can carry particles outward from airways, acts as an escalators
-Lacrimal secretions (tears):washes irritants and foreign objects from eyes.

Question 5

What is the complement system (humeral) in the innate or non-specific defences? Explain

Answer 5

Humoral (system derived from body fluids) reactions play a role in inflammation.

Complement system: Circulating family of immune molecules (serum proteins). The major humeral, non-specific defence mechanism is the comp system. Once activated complement can lead to increased vascular permeability, recruitment of a phagocytic cells, and lysis and opsonization of bacteria.

Question 6

What are 3 roles of the Complement System (Humoral Defences)? Explain.

Answer 6

Complement fixation- binding to & destroying foreign cell membrane
Opsonization- “tagging” of foreign cells for stimulation of phagocytosis (engulfing a cell to destroy)
Trigger inflammatory reaction: that “walls off” damaged tissue.

All of these processes are very destructive and are related to prevent unnecessary cell damage.

Question 7

What are types of humeral defences?

Answer 7

Cytokines “communication molecules”: Interleukin-1 induces fever and production of acute phase proteins,some are antimicrobial bc they can opsonize bacteria
Lysozyme (found in tears): breaks down the cell wall of bacteria

Question 8

What are the cellular defences (white blood cells) for non-specific (innate) immunity?

Answer 8

Phagocytes: Neutrophils (polymorphonuclear) and macrophages.

-Non-speficifally engulf and digest foreign particles.
-LACK MEMORY (therefore next time won’t recognize antigen and slower response).
-Contributes to inflammatory response.
-Monocytes and macrophages (not PMN’s) work as Ag-presentning cells (APC) to the specific immune system

Question 9

TRUE OR FALSE: Neutrophils are the most common white blood cells.

Answer 9

TRUE: 55-70% of WBC.
-They ingest and digest foreign particles (phagocytosis) digestion by lysozymes (breakdown cell wall of bacteria).

Question 10

How do neutrophils function in the immune system?

Answer 10

-Attracted to sites of infection or inflammation by chemotaxis (chemical signalling ex cytokines, interleukin).
-When activated by chemical signalling, neutrophils become “sticky” and marginate in circulation: blood
-then they squeeze through endothelial (lining of blood vessels) junctions (diapedesis) and migrate to the sit of infection or tissue damage.

In additional to phagocytosis, neutrophils relates cytokines to initiate specific immune cell response. IMPORTANT in mammary glands and uterus.

Question 11

TRUE OR FALSE: Monocytes are the largest cell of WBC. EXPLAIN Monocytes function as well.

Answer 11

TRUE: Small quantity but largest size 5-8% of total WBC
-Cytoplasm contains lysosomes (breakdown cell wall of bacteria).
- Eventually leave circulation to become macrophages in tissue

Functions:
-Non-specific removal of bacteria, fungi, necrotic debris (dead cells or debris associated with dead tissue)
-Act as Antigen presenting cell (APC) to T lymphocytes

Question 12

TRUE OR FALSE: Macrophages are in tissues but are previously monocytes in circulation.

Answer 12

TRUE: Monocytes migrate to tissues or reside in specific location (liver, lung, spleen) the differentiate into MACROPHAGES.

-Activated by phagocytosis of certain antigens secretions of T cells and bacteria cell walls
-Migrate to cites of infection/inflammation (chemotaxis like neutrophils)
-Functions APC’s (antigen presenting cell like monocytes) and activate helper T cells

Question 13

Are B and T lymphocytes apart of the specific (Adaptive) or Non-specific (innate) immune system?

Answer 13

Specific Immune: Each mature lymphocyte has the receptors to recognize specific antigens. Meaning it has a memory and a greater and faster response to previously encountered antigens.

Question 14

What are the two wings of the Specific Immune System? and what are the parts?

Answer 14

Humoral Wing:
-B cells (plasma cells and memory cells)
-Production of specific antibodies (IggM, IgG, IgA,IgE)

Cell mediated Wing:
-Macrophages
-T cells (helper CD4+, suppressor CD8+, and Killer CD8+)
-Cytokines
-Destroy tutor cells and cells infected with virus

Question 15

What are 2 types of lymphocytes and where are they found in the body? Where are they stored?

Answer 15

B cells: From bone marrow- humoral immunity
T cells: From bone marrow, mature in the thymus-cell mediated immunity

Both are stored in lymph nodes, lymphoid tissue (spleen).

Question 16

Explain the B lymphocytes antibody production.

Answer 16

-“Naïve” lymphocytes scans for antigens in blood and lymph nodes
-The stimulated B cell divides repeatedly
-Forms a clone of antibody secreting plasma cells
-This large population of cells produces sufficient quantities of antibody to help WBC destroy the bacteria
-After the assault is over, some become memory B cells

Question 17

What are the functions of the Immunoglobins / Ig (antibodies)?

Answer 17

Multiple types: (IgA, IgA, IgG, IgE) All are proteins produced by B cells (plasma cells)
-Antigen-antibody complexes stimulate additional production of antibody
Function:
-Released into the intercellular fluid where they bind to the infecting antigen and flag it for destruction by phagocytes and the complement system
-Coating may prevent attachment or invasion by bacteria or viruses
-Bind toxins secreted by pathogens

Question 18

What are the 4 types of antibodies and their form/purpose?

Answer 18

IgA: Found on mucosal surfaces - GI, reparatory, reproductive tracts. Forms 10-15% of total in body

IgM: Circulates mainly in blood, not tissue. Generally produced most quickly in response to antigenic stimulation (antigens on virus). Forms about 5-10% of total in body

IgG: Equally in circulation and tissue (migrates to sites of infection, crosses placenta). Has the longest half-life of all and most common 80% in body.

IgE: Associated with parasites and allergies

Question 19

What is the job of helper and killer T cells?

Answer 19

Helper T cells: “sees” the same antigen on both the macrophage and B cells, the T cell stimulates the B cell to start producing antibody by releasing interleukins. After assault ended some remain as memory helper T cells.

Cytotoxic (killer) T cells: Recognize infected cells bearing specific antigen completes. They destroy the cells by dissolving cell membranes. Some remain as memory killer T cells (unequal amount at times).

Question 20

Why is nutrition important to the immune system to function?

Answer 20

Immune system is energy demanding, antibodies are proteins so they require dietary amino acids. Numerous vitamins and minerals are specific co-factos and enzyme components in phagocytic and cell lysis reactions.

Vitamin E and A, selenium, copper help protect phagocytes from oxidative damage from radicals generated in digestion. Iron and Zinc are co-factors.

Question 21

TRUE OR FALSE: Vaccination means the same as immunization, but “strategic” vaccination is different.

Answer 21

FALSE: They are all different.
Vaccination= to administer a vaccine (more action)
Immunize: to stimulate/confer a protective immune response (more biological response we are hoping for)
“Strategic” vaccination: To administer a vaccine in such a way (usually timing) to maximize changes of protection against condition of interest.

Question 22

What are 2 types of vaccines and how are the different?

Answer 22

Modified Live vaccines: Lab-attenuated virus to produce a low-level “true” infection, replicates in host. (fEx flu allows to retain memory)

Killed Virus Vaccines: Completely inactivated, no replicated. Adjuvants added to increase immune response. (Ex rabies),(Not inducing a low level infection.)

Question 23

What are some advantages and disadvantages of Killed Virus Vaccines?

Answer 23

Advantages:
-Generally stimulate good humeral response, can be used In all stages of production. No risk of shedding, or reversion to virulence (never revert back to virus).
-Properly stored a partial bottle can be used: greater stability, less concern about stage of gestation at time of vaccination. Can incorporate new “strains” easier.

Disadvantages: Primer dose needs to be “boostered” in 2-4 weeks which is more $$ and time. The ability to stimulate CMI (cell mediated immunity) is not known.
-Antibodies alone not protective for many diseases (may not be ideal depending on what disease). Antibodies produced against strains in the vaccine, more $$, higher levels of antibody for approximately 4-6 months- when boostered.

Question 24

What are some advantages and disadvantages of modified live Vaccines (MLV)?

Answer 24

Advantages: Stimulates cell mediated and humeral wings of immune system. Single dose will usually provide protection. Less $$ per dose and more rapid immune response, longer lasting protection.

Disadvantages: Historically can’t be given to pregnant animals there are now exceptions but depends on vaccine can be tricky that’s why its important to read the label. Need to be reconstituted prior to use (vaccine and dilutent).
-Can be inactive by heat, sunlight, chemical residues in syringe, must be used within hours, partial bottles can not be stored.

Question 25

What are the 3 E’s when deciding to vaccinate to not?

Answer 25

Efficacious: Can it work? Get from lab testing ie research saying it works
Effective: Does it work? Field trials in population using it on affected in different groups/settings
Efficient: Is it worthwhile? the economics, is labour envied for administering worth it etc.