Vaccine Immunology Flashcards
Goal of vaccines
Stimulate an immune response in an animal in order to provide protection against infectious disease
- prevent disease
- decrease disease severity/frequency
Vaccines stimulate/mimic ______
Adaptive immunity
What type of immunity is important for virus immunity?
Humoral immunity
Vaccine targets
Extracellular pathogens
- targeted by humoral immunity (affected by B cells)
Intracellular pathogens
- targeted by cell-mediated immune response (affected by T cells)
Biological toxins
- antibodies mark toxin for destruction
Characteristics of the perfect vaccine
- safe
- protective
- provides long-lasting effects
- induces formation of protective antibodies
- induces formation of protective T cells
Passive immunization
Transfer of ready-made antibodies to an individual
- provides immediate humoral protection
- does not induce an immune response from host (no memory)
Passive clinical examples
- rabies post-exposure prophylaxis
- tetanus
- antivenin
- plasma transfusions
Passive immunization via transfer of maternal antibodies
Passive transfer of maternal antibody through placenta
Ingestion of colostrum via initial suckling
- GIT has maximal permeability to proteins from 0-4 hrs, closes by approx 24 hrs
Pro of maternal antibodies
Provides immediate protection of the neonate against pathogens and lasts for 6-16 weeks of age
Con of maternal antibodies
Interferes with vaccination of neonate via binding of maternal antibody to the antigen in the vaccine (neutralizaiton)
- aka immunity gap
Passive immunization strategy
Administer multiple, sequential vaccines to puppies and kittens until at least 16 weeks of age
- 1st vaccine: initial response takes 10-14 days with max response at 3 weeks
- 2nd vaccine: leads to immunological memory
- 3rd and 4th vaccine: stronger and more rapid memory
Immunity gap
Maternal antibody can interfere with vaccination even when level of antibodies is not sufficient to protect against pathogens
Killed vaccines
Organism is completely inactivated
- may require adjuvant to stimulate immune system
Modified-live vaccines
Organism is modified to a less virulent state (attenuated)
Recombinant vaccines
Introduce genes into an attenuated vector organism
Gene deletion
Method of attenuation to change virulence
Purified subunit
Genes from pathogen inserted into non-pathogenic bacteria, which then produce the protein that can be harvested and used as a vaccine
Vectored
Incorporates immunogenic genomic regions from pathogen into attenuated nonpathogenic virus
DNA vaccines
Insert pathogen DNA into a plasmid and inject into patient
- DNA is then transcribed and translated in the patient to proteins that prime immune system
Pros of modified live vaccines
- rapid and prolonged protection
- stimulates CMI and long-lived humoral immune response
- reduced allergenicity
- stimulates secretory antibody
- lower antigen mass needed
- single dose effectiveness
Cons of modified live vaccines
- no preservatives for storage
- requires multiplication in host
- susceptible to inactivation
- risk of reversion to virulence
- can produce vaccine-induced illness in immuosuppressed hosts
- vaccinates can shed into environment
Pros of killed vaccines
- no reversion to virulence
- stability in storage
- increased immunity with added adjuvants
- safe in immunosuppressed animals
- vaccinates do not shed organisms
Cons of killed vaccines
- stimulates humoral immunity
- minimum of 2 doses needed for protection
- increased risk of allergic complications
- shorter duration of immunity
- adjuvants frequently required
- Ag may not induce proper Ab if too denatured
Adjuvants
Substances that enhance the immunogenicity of vaccines
- stimulate cell-mediated immunity
- used with killed organisms or purified antigens
- attempts to increase duration and amount of immunostimulation equal to MLVs
- produces heightened inflammatory reaction
Vaccine associated sarcomas in cats
Underlying theme of sarcoma development = inflammation
- caused by any injection
- cold vaccines
Vaccine recommendations in cats
- inform O of risks and carefully recommend vaccines
- use minimally inflammatory products
Appropriate vaccination sites
Rabies: low on the lateral right hindlimb (below stifle)
FeLV: low on the lateral left hindlimb (below stifle)
FPV/FHV-1/FCV: lateral aspect of right forelimb below elbow
Core vaccines
- infection has high risk of morbidity and mortality
- infections are of public health concern
- infections are readily transmitted
- infections are ubiquitous in environment
Use when: safe, efficacious vaccines are available, and vaccines prevent infection or decrease clinical signs
DA2P (parvo)
Parvovirus (CORE vaccine) Highly contagious and usually fatal if untreated - fecal oral route - survive in environment > 1 year - attacks rapidly dividing cells
DA2P (distemper)
Highly contagious, can be fatal
- causes multisystemic disease in unvaccinated animals (respiratory, neurologic, GI)
- transmitted thru all bodily secretions, most commonly aerosol or droplet exposure
DA2P (canine adenovirus type-1)
Infectious canine hepatitis
- potentially fatal, but almost eradicated
- liver, kidneys, and eye targeted
- vaccinate with type-2 (A2) which usually causes respiratory signs)
- vaccination with CAV-1 led to blue eye
Rabies
Core vaccine
- can infect any mammalian species thru saliva
- low morbidity, 100% mortality if symptomatic
- zoonotic
- vaccine mandatory by law
Canine non-core vaccines
- vaccine may have limited efficacy
- disease not readily transmitted
- limited geographic distribution or prevalence
- disease is mild
- vaccines may interfere with diagnostic screening
Leptospirosis
Non-core
- bacterial pathogen causing acute hepatic and renal disease
- transmitted thru urine
Bordetella
Non-core
- bacterial pathogen causing infectious tracheobronchitis along with canine parainfluenza
- transmitted by direct contact or by aerosolized microdroplets
- intranasal superior to parenteral
Other canine non-core vaccines
- parainfluenza
- borreliosis
- measles
- canine influenza
- rattlesnake
- coronavirus
- canine adenovirus type 1
FVRCP (feline viral rhinotracheitis)
Feline herpesvirus - 1
- cause 40-45% of feline upper respiratory infecitons
- causes conjunctivitis with coughing/sneezing
- 80% latency, 50% recrudesce with stress
- high morbidity, low mortality
- vax decreases clinical signs
FVR recommendations
Cats can persistently shed virus
- prevention before exposure is key!
- MLV or killed vax at 6-9 weeks old (right front)
FVRCP (feline calicivirus)
Non-enveloped RNA virus
- more likely to cause oral ulceration
- 20-30% cats chronic carriers (shed virus continuously)
- high morbidity, low mortality
FVRCP (panleukopenia)
Feline infectious enteritis
- feline parvovirus (intestinal crypts, bone marrow affected)
- cerebellum and retina affected in fetal and neonatal kittens (cerebellar hypoplasia)
- long lasting immunity if affected
- low morbidity, high mortality
Feline rabies recommendations
Initial vaccine at 12 weeks with recombinant vaccine
- distal right hind limb
- give recombinant vaccine annually
FeLV
Feline leukemia virus
- retrovirus (horizontal and vertical transmission)
- develop age-related immunity, more common to become viremic when <2 yrs old
- friendly cat disease
- vaccine is one of the top 2 associated with the development of vaccine sarcomas
FeLV recommendations
Recommended to vaccinate when <1 yr and booster in 1 yr
- viral screening of all kittens with ELISA prior to vaccination
- use killed or recombinant vax at 1 or 2nd kitten visit
- left hind limb
- non - core vaccine for adult cats
Feline non-core vaccines
Chlamydiosis
- poor vax, adverse effects
Bordetella
- use if exposed to canine outbreak
Feline vaccines not recommended
Feline Immunodeficiency Virus
- retrovirus spread thru bite wounds
- causes immunosuppression
- SNAP test commonly used for diagnosis is for antibodies to FIV, so vaccinated animals are positive
Vaccinating older animals
Can mount an adequate immune response
- 2 vaccinations given 3-4 weeks apart are considered protective in animals >16 weeks
- one MLV would likely be protective
- duration of immunity has been shown to be up to >5 yrs for many core products
Adverse reactions
Feline injection site sarcomas
- avoid adjuvants
- 3-2-1 rule: persists for longer than 3 months, greater than 2 cm, increases in size after 1 month
Dogs core vaccine summary
- distemper (R or MLV)
- adenovirus-2 (MLV)
- parvovirus-2 (MLV)
- rabies (K)
Dogs non-core vaccine summary
- bordetella (K or ML)
- parainfluenza (MLV)
- lyme disease (K or R)
- leptospira (K)
- influenza (K)
Dogs not recommended summary
- coronavirus (K, MLV, or R)
- giardia lambila (K)
Cats core vaccine summary
- herpesvirus-1 (K+A or MLV)
- calicivirus (K+A or MLV)
- panleukopenia (K+A or MLV)
- rabies (K or R)
- kitten feline leukemia virus (K + A or R)
Cats non-core vaccine summary
- bordetella (ML)
- adult feline leukemia virus (K+A, or R)
- feline immunodeficiency virus (K+A)
- chlamydophila felis (K+A, ML)
Cats not recommended summary
- feline infectious peritonitis (MLV)
- feline giardia lamblia (K+A)
