26- Vaccine Immunology Flashcards
What is passive immunity?
the transfer of specific antibodies or immuno-reactive substances from one individual to another
What is active immunity?
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
What are forms of passive immunity
- maternal immunity either placental or colostral, or prophylactic/theraputic treatments such as tetanus toxoid
What are the ‘biggest roles’ passive immunity plays in veterinary medicine?
Transfer in foals and snake venom toxin in SAM
The vaccine design must deliver the antigen efficiently to ________.
APCs
Why should both B and T cells be stimulated by a vaccine?
- to generate humoral and cellular immunity
- to generate large numbers of memory cells
Why should T cells be reactive to multiple epitopes in the vaccine?
To improve the likelihood of responses across MHC II alleles (ideally broad spectrum)
What are some advantages of noninfectious vaccines?
- 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
What are some disadvantages to noninfectious vaccines?
- weak immunogenicity
- require an adjuvant (increased the duration and amount of immuno-stimulation; mechanism for most is poorly understood)
- adjuvants can cause local reactions
Describe the vehicles/depots type of adjuvant
Maintain the antigen at specific site and intensify the response
- examples: metallic salts, oils, lipids, mineral gels, liposomes
Describe the immunomodulators type of adjuvant
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.
Non-infectious vaccine stimulate primarily which type of immunity?
Th2 humoral immunity
What is the mechanism of infectious vaccines?
Vaccines that ‘infect’ or ‘transfect’ cells and use host machinery to promote immunologic response
- the infection process amplifies overall immune response
What are some advantages of infectious vaccines?
- 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
What are the types of live (infectious) vaccines
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)
Modified live vaccines infect host cells. Modifications decrease virulence while maintaining __________.
Immunogenicity
- usually through prolonged tissue culture in non-host species
- No adjuvant required
- lower antigen mass needed
- stimulate TH1 and Th2 responses
How does a recombinant vector in a live vaccine trigger an immune response?
Used as carriers to express antigens of other pathogens
- insertion of genes for protective antigens into genome of another agent
How does a DNA-based live vaccine trigger an immune response?
- 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)
How to select the appropriate vaccine for a vaccination protocol
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
What factors should you consider when determining when to give the initial vaccination in a vaccination protocol?
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
What are some host factors that cause vaccine failures?
- maternal immunity
- immunosuppression or concurrent illness
- age
- genetics- ability to respond
What are some vaccine factors that cause vaccine failures?
- route
- vaccine design
- antigenic variation (flu vaccine)
What are some human factors that cause vaccine failures?
Improper selection
Storage
Preparation
Administration
Give some examples of Type I adverse effects from vaccines
Facial edema, pruitis, wheals
Anaphylaxis
Give some examples of type II hyper sensitivity as an adverse effect from a vaccine
IMHA (Immune-mediated Hemolytic Anemia), ITP, definitive data lacking
Give some examples of type III hyper sensitivity as an adverse effect from a vaccine
Post-vaccine vasculitis, blue eye
Delayed 1-3 months post-vaccine
Give some examples of type IV hyper sensitivity as an adverse effect from a vaccine
Postvaccinal encephalomyelitis
