Immunology: Vaccines Flashcards
Vaccination
introduction of a compound into the body to stimulate an immune response to a specific disease
immunization
process by which a person becomes protected against a disease through vaccination
inoculation
can mean the same as vaccination, or to introduce a micro-organism
passive immunization
Administration of preformed antibodies
Immediate protection
Short-lived with no memory
Does not protect fetus
Repeated use can cause hypersensitivity
Examples: tetanus antitoxin, antivenom for snake/spider bites
active immunization
Administration of antigen to induce an immune response
Delayed protection
Long term with memory
Can protect fetus
Hypersensitivity is less common
Examples: most vaccines for infectious agents
acquired immunologic memory
APC presents antigen to Th cell
Th differentiates into Th1 ans Th2
Th1 activates cytotoxic T cells
Th2 cells activate B cells into plasma and memory cells
innate immunologic memory
NK cells, monocytes, and macrophages
“Training” with repeated exposure to pathogens
Mechanisms:
* Altered PRR expression
* Metabolic changes
* Epigenetic reprogramming
* Altered cytokine release
Often enhanced by use of adjuvants
adjuvant
Chemicals, microbial components, or proteins used to enhance the immune response to antigens in a vaccine
Mechanism:
* Enhance antigen presentation
* Improve antigen stability
* Act as immunomodulators
* Some association with adverse effects
Uses:
* reduce dose amount
* reduce # of immunizations
* oversome elderly immune senescence
Live Virulent Vaccines
Uncommon
Risk of causing clinical disease
Parapoxvirus (contagious ecthyma) in sheep
Scarification of the virus on the skin
Modified Live Vaccines
Most common type
Pathogen is altered to reduce virulence
* Heat
* Passage through cell culture
* Genetic engineering
Downsides:
* May revert to virulence
* May cause disease if inhaled or ingested (Feline herpesvirus)
* Possibility for contamination
* Less stable than killed vaccines
* Often require refrigeration
* Blocked by maternal antibodies
* Usually not recommended for vaccination of pregnant females
ex: DAP vaccine
cell passage for modified live viruses
- live virus taken from patient
- virus cultured on other cells of wrong host
- virus grows less well, acquires mutations
- mutated virus no longer lives well in original host
- modified virus used as vaccine
genetic engineering modified live viruses
- isolate virus
- isolate virulence gene
- mutate or delete virulence gene
- use modified virus as vaccine
(recombinant DNA technology)
immunological protection of newborn/young animals
Mechanism of antibody transfer depends on type of placenta
Maternal antibodies block the response to some types of vaccines
* Even when antibody levels are too low to be protective
Whole Killed Organism Vaccine
Organism is antigenically intact
Unable to replicate or cause disease
* Treated with chemicals such as formalin, alcohol, alkylating agents
Require adjuvant
Less effective than modified live vaccines (more doses required)
* Unlikely to produce a Th1 response (cannot replicate intracellularly)
used to make Autologous/Autogenous Vaccines
ex: rabies, canine influenza
Autologous/Autogenous Vaccines
killed vaccine
Self or custom vaccines
- Isolate bacteria/virus/tumor cells from sick animals
- Kill organism/tissue
- Add adjuvant
- Inject into same animal (autologous) or herdmates (autogenous)
Examples:
Pink eye (Moraxella sp.) in cattle
Papillomavirus
Autologous tumor vaccines
recombinant vaccines
Benign carrier organism (ex: Canarypox) engineered to include a gene for a protein from another pathogen
Complex to make = $$$$
Can induce immunity even with maternal antibodies
No adjuvant needed
Cannot revert to virulence
subunit vaccine
Immunogenic proteins and metabolites from pathogen
Subunits are produced by viral or bacterial cultures
Requires adjuvant
Economical
toxoid
Chemically modified toxin
No longer toxic
Antigenic
Antibodies bind toxin and prevent interaction with receptor
ex: tetanus antitoxin
Genetic (naked DNA) vaccine
- Pathogen gene inserted into bacterial plasmid
- Plasmid introduced into host (Injection, Transdermal, Mucosal administration)
- Plasmids transfect host cells, including APCs
- Gene is expressed and protein is presented on APC surface
- Mixed Th1 and Th2 response
Not inactivated by maternal antibodies
mRNA vaccine
- Contain mRNA encoding one or more antigen
- Translated by host ribosomes into proteins
Encapsulated in lipid nanoparticles
* Protection
* Promotes cellular uptake
Advantage
* Rapid production
Differentiating infected from vaccinated animals (DIVA)
Marker vaccines
* Induce an immune response that is different that in natural infection
Laboratory tests such as ELISA can be used to diagnose a breakthrough infection in an immunized animal
Currently available for:
* Pseudorabies in pigs
* Infectious bovine rhinotracheitis in cattle
* Bovine herpesvirus 1
* Classic swine fever
* Foot and mouth disease
vaccine failure
animal related:
* immunodeficiency
* poor health
* waning immunity
vaccine related:
* low potency
* incorrect serotype
* poor match to strain
* interference from other vaccines
failure to vaccinate:
* incorrect usage (most common)
* incorrect timing, schedules
vaccine adverse effects
Rate of adverse effects: 1-50 in 10,000
Normal response: Mild pain, fever, lethargy, transient immunosuppression
serious: vomiting, diarrhea, swelling collapse
type 1 sensitivity vaccine reaction
Swelling of head
Hives
Diarrhea
Vomiting
Anaphylaxis (uncommon)
