Immunology: Vaccines

Question 1

Vaccination

Answer 1

introduction of a compound into the body to stimulate an immune response to a specific disease

Question 2

immunization

Answer 2

process by which a person becomes protected against a disease through vaccination

Question 3

inoculation

Answer 3

can mean the same as vaccination, or to introduce a micro-organism

Question 4

passive immunization

Answer 4

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

Question 5

active immunization

Answer 5

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

Question 6

acquired immunologic memory

Answer 6

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

Question 7

innate immunologic memory

Answer 7

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

Question 8

adjuvant

Answer 8

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

Question 9

Live Virulent Vaccines

Answer 9

Uncommon
Risk of causing clinical disease
Parapoxvirus (contagious ecthyma) in sheep
Scarification of the virus on the skin

Question 10

Modified Live Vaccines

Answer 10

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

Question 11

cell passage for modified live viruses

Answer 11

1. live virus taken from patient
2. virus cultured on other cells of wrong host
3. virus grows less well, acquires mutations
4. mutated virus no longer lives well in original host
5. modified virus used as vaccine

Question 12

genetic engineering modified live viruses

Answer 12

1. isolate virus
2. isolate virulence gene
3. mutate or delete virulence gene
4. use modified virus as vaccine

(recombinant DNA technology)

Question 13

immunological protection of newborn/young animals

Answer 13

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

Question 14

Whole Killed Organism Vaccine

Answer 14

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

Question 15

Autologous/Autogenous Vaccines

Answer 15

killed vaccine
Self or custom vaccines

1. Isolate bacteria/virus/tumor cells from sick animals
2. Kill organism/tissue
3. Add adjuvant
4. Inject into same animal (autologous) or herdmates (autogenous)

Examples:
Pink eye (Moraxella sp.) in cattle
Papillomavirus
Autologous tumor vaccines

Question 16

recombinant vaccines

Answer 16

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

Question 17

subunit vaccine

Answer 17

Immunogenic proteins and metabolites from pathogen
Subunits are produced by viral or bacterial cultures
Requires adjuvant
Economical

Question 18

toxoid

Answer 18

Chemically modified toxin
No longer toxic
Antigenic
Antibodies bind toxin and prevent interaction with receptor
ex: tetanus antitoxin

Question 19

Genetic (naked DNA) vaccine

Answer 19

1. Pathogen gene inserted into bacterial plasmid
2. Plasmid introduced into host (Injection, Transdermal, Mucosal administration)
3. Plasmids transfect host cells, including APCs
4. Gene is expressed and protein is presented on APC surface
5. Mixed Th1 and Th2 response

Not inactivated by maternal antibodies

Question 20

mRNA vaccine

Answer 20

1. Contain mRNA encoding one or more antigen
2. Translated by host ribosomes into proteins

Encapsulated in lipid nanoparticles
* Protection
* Promotes cellular uptake

Advantage
* Rapid production

Question 21

Differentiating infected from vaccinated animals (DIVA)

Answer 21

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

Question 22

vaccine failure

Answer 22

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

Question 23

vaccine adverse effects

Answer 23

Rate of adverse effects: 1-50 in 10,000
Normal response: Mild pain, fever, lethargy, transient immunosuppression

serious: vomiting, diarrhea, swelling collapse

Question 24

type 1 sensitivity vaccine reaction

Answer 24

Swelling of head
Hives
Diarrhea
Vomiting
Anaphylaxis (uncommon)

Question 25

vaccine reaction type II hypersensitivity

Answer 25

Immune mediated hemolytic anemia
Immune mediated thrombocytopenia
Dogs

Question 26

vaccine reaction type III hypersensitivity

Answer 26

Arthus reaction
Asymptomatic, hyperpigmented area at site of vaccination
Can stay for several months after vaccination
Lymphocytic vasculitis

Question 27

vaccine reaction type IV hypersensitivity

Answer 27

Post-injection panniculitis

Vaccine-associated sarcoma
* Rare
* Aggressive mesenchymal tumor
* Genetic predisposition suspected
* Associated with:
* Rabies vaccine
* FeLV vaccine
* Microchip
* Long-acting antibiotic or steroid injections