26- Vaccine Immunology

Question 1

What is passive immunity?

Answer 1

the transfer of specific antibodies or immuno-reactive substances from one individual to another

Question 2

What is active immunity?

Answer 2

Stimulating the host with all or part of an organism (antigen/immunogen). Produces an active immune response.

Can be achieved through natural infection or vaccination

Question 3

What are forms of passive immunity

Answer 3

• maternal immunity either placental or colostral, or prophylactic/theraputic treatments such as tetanus toxoid

Question 4

What are the ‘biggest roles’ passive immunity plays in veterinary medicine?

Answer 4

Transfer in foals and snake venom toxin in SAM

Question 5

The vaccine design must deliver the antigen efficiently to ________.

Answer 5

APCs

Question 6

Why should both B and T cells be stimulated by a vaccine?

Answer 6

• to generate humoral and cellular immunity
• to generate large numbers of memory cells

Question 7

Why should T cells be reactive to multiple epitopes in the vaccine?

Answer 7

To improve the likelihood of responses across MHC II alleles (ideally broad spectrum)

Question 8

What are some advantages of noninfectious vaccines?

Answer 8

• noninfectious vaccines may contain partial or whole pathogen
• inactivated/ killed fail to replicate in the host
• stable storage
• safe in immunosuppressed patients (pregnant patients)
• Th2 CD4+ responsive

Question 9

What are some disadvantages to noninfectious vaccines?

Answer 9

• weak immunogenicity
• require an adjuvant (increased the duration and amount of immuno-stimulation; mechanism for most is poorly understood)
• adjuvants can cause local reactions

Question 10

Describe the vehicles/depots type of adjuvant

Answer 10

Maintain the antigen at specific site and intensify the response
- examples: metallic salts, oils, lipids, mineral gels, liposomes

Question 11

Describe the immunomodulators type of adjuvant

Answer 11

Enhance the cell mediated immunity, provide slow antigen release and degradation, stimulate cytokine release, activate innate immunity
- examples: bacterial components, CpG islands, dextran sulfate, acemannan, saponin, lecithins, etc.

Question 12

Non-infectious vaccine stimulate primarily which type of immunity?

Answer 12

Th2 humoral immunity

Question 13

What is the mechanism of infectious vaccines?

Answer 13

Vaccines that ‘infect’ or ‘transfect’ cells and use host machinery to promote immunologic response
- the infection process amplifies overall immune response

Question 14

What are some advantages of infectious vaccines?

Answer 14

• single inoculation may be protective
• provides prolonged immune exposure
• increased immunogenicity and memory cell production
• lower chance of hypersensitivity
• inexpensive
• may be given by natural route

Question 15

What are the types of live (infectious) vaccines

Answer 15

Most contain attenuated whole organisms- usually multiple mutations (from prolonged tissue culture)
- modified life- virulence gets removed
- temp sensitive mutants- replicated in nasal cavity but not in lower respiratory tract
- Non- encapsulated bacterial such as Strep equi in strangles vaccine (loses ability to cause disease)

Recombinant vectors

Nucleic acids (DNA vaccines)

Question 16

Modified live vaccines infect host cells. Modifications decrease virulence while maintaining __________.

Answer 16

Immunogenicity

• usually through prolonged tissue culture in non-host species
• No adjuvant required
• lower antigen mass needed
• stimulate TH1 and Th2 responses

Question 17

How does a recombinant vector in a live vaccine trigger an immune response?

Answer 17

Used as carriers to express antigens of other pathogens
- insertion of genes for protective antigens into genome of another agent

Question 18

How does a DNA-based live vaccine trigger an immune response?

Answer 18

• bacterial DNA activates innate response
• injection into muscle cells leads to expression and cross-presentation (low efficiency, can target MCH I or MCH II based on sequence)

Question 19

How to select the appropriate vaccine for a vaccination protocol

Answer 19

MLV vs. Killed
- depends on the health of the animal, pregnancy status, age and if herd immunity (MLV is better for herd immunity because of virus shedding)

Route of transmission
- mucosal (oral) vs. systemic infections (parenteral)
- systemic generate IgG
- adverse effects

Question 20

What factors should you consider when determining when to give the initial vaccination in a vaccination protocol?

Answer 20

Age of vaccination
- newborns are too young
- maternal antibodies can interfere with response from vaccine- levels pend maternal titers
- several doses at intervals of 3-4 weeks

Question 21

What are some host factors that cause vaccine failures?

Answer 21

• maternal immunity
• immunosuppression or concurrent illness
• age
• genetics- ability to respond

Question 22

What are some vaccine factors that cause vaccine failures?

Answer 22

• route
• vaccine design
• antigenic variation (flu vaccine)

Question 23

What are some human factors that cause vaccine failures?

Answer 23

Improper selection
Storage
Preparation
Administration

Question 24

Give some examples of Type I adverse effects from vaccines

Answer 24

Facial edema, pruitis, wheals
Anaphylaxis

Question 25

Give some examples of type II hyper sensitivity as an adverse effect from a vaccine

Answer 25

IMHA (Immune-mediated Hemolytic Anemia), ITP, definitive data lacking

Question 26

Give some examples of type III hyper sensitivity as an adverse effect from a vaccine

Answer 26

Post-vaccine vasculitis, blue eye
Delayed 1-3 months post-vaccine

Question 27

Give some examples of type IV hyper sensitivity as an adverse effect from a vaccine

Answer 27

Postvaccinal encephalomyelitis