AOD - Vaccines (exam 2)

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Terms in this set (...)

Vaccinology
Science of vaccines.

Wow. Didn't see that coming.
Advantages of vaccinations (4)
Preventing/curing viral infection in the absence of antivirals

Environmentally friendly

Increase animal welfare by preventing suffering from disease

Protect human health from zoonotic infection
Goals for swine vaccines (6)
Prevent infection

Protect against disease & prevent or minimize spread of the agent

Induce sterilizing immunity

Have markers to allow for differentiation b/n infected & vaccinated

Protect at mucosal sites

Be able to deliver to newborns w/o impact of passive immunity
Vaccination
Deliberate exposure to an antigen under conditions where disease will not result
First vaccination
Edward Jenner used cowpox vaccination to protect against smallpox in 1796
Developer of chicken cholera vaccine & rabies vaccine
Louis Pasteur

He did some other important things you may remember that are definitely not named after him because he's a humble gentleman. That would be pasteurization. Oh wait... that is named after him.
Immunization
Providing the body w/ specific defenses against an antigen
Passive immunization
Protection of one individual via transfer of Ab (or B cells or T cells yadda yadda) from another individual
3 Downsides of passive immunization
Usually short-lived (no memory)

Can induce hypersensitivity reactions

Can transfer other infectious agents
Natural passive immunity
Passed from mother to fetus/neonate through placenta or colostrum
Artificial passive immunity
Abs from one individual are given to another
Active immunization is also known as......
Vaccination!
Advantages of active immunization (4)
Uses the individual's immune system to generate protection

Prolonged protection

Memory cells formed

Boosting is possible
Ideal vaccine will...(3)
Induce immunity in most individuals

Give long-lived immunity to all strains/variants

Not be toxic or induce illness at any level
Subunit vaccine
Contains some part or product of microorganisms that can produce an immune response
Examples of subunit vaccines (4)
Recombinant, toxoid, conjugated, or acellular vaccines
Whole-agent vaccine
Contains whole, nonvirulent microorganisms
Example of whole-agent vaccines
Attenuated or inactivated vaccines
Disadvantages of killed vaccines (4)
Mostly induce antibodies only

since they cannot get into the cytoplasm, it is difficult to induce Cytotoxic T Lymphocyte responses

B/c the organism doesn't multiply, these vaccines require large amounts of antigen

Usually protection is shorter term
Why is protection shorter term in killed vaccines? (2)

What can be done to improve the protection for that amount of time (or extend the amt of time)? (2)
Poor induction of memory B cells

Usually very little IgA put onto mucosal surfaces

Boosters required

Usually include an adjuvant to boost immune response
Advantages of killed vaccines (2)
More stable in storage

Unlikely to cause disease/illness in immunocompromised recipient
Organisms cannot be killed by heat for vaccine b/c...
Heat treatment causes proteins to denature, losing antigenic integrity
Common method of killing organisms for vaccines
Chemical inactivation, but the chemical must be removed prior to vaccination in order to avoid toxicity

Commonly used chemicals include formaldehyde or beta-propriolactone
Inactivated vaccines can be live organisms that...
Are unable to replicate.
Most live vaccines induce what types of responses (2)?
Th1 & Th2 responses.
Viral Vaccines tend to induce a strong _______ response
CTL
Live vaccines usually contain...

Why would this be chosen?
Attenuated organism; selected b/c it has limited virulence. Will still cause infection, but not disease
Attenuation is achieved by...
Growing the organism in vitro until it loses virulence.

Or you can do the more time-efficient thing and use rDNA to remove or mutate virulence genes.
Subunit vaccines contain...
Defined proteins from an infectious agent, rather than the whole organism

Includes vaccines including those in which antigen is complexed w/ a carrier protein to increase immunogenicity
Recombinant vector vaccine
Inserting the gene for an antigen into a harmless vector, which is a live organism that does not cause disease. The vector produces the protein, thus vaccinating the recipient
Advantages of live vaccines (5)
Few inoculating doses required

Adjuvants unnecessary

Less chance of hypersensitivity

Induction of interferon

Relatively cheap
Major disadvantage of subunit or component vaccines
Only stimulate immunity against a single protein, which may not impart full protection. You could choose the wrong antigen to vaccinate against.
Toxoid vaccines can be made by...
Treating toxins w/ chemical inactivators like formalin or denaturing using heat
Example of a toxoid-based vaccine
Vaccination against atrophic rhinitis in pigs

Contains Pasteurella multocida type D dermonecrotoxic toxoid, Bordetella bronchiseptica cell suspension, & Pasteurella multocida cell suspension
Conjugate vaccine

Common for making vaccines against what?
Takes something that is not immunogenic & attaches it to something it is. Common for making vaccines against bacteria w/ capsules (polysaccharides)
Hapten-carrier effect
Raising antibodies against a poor antigen by covalently linking the antigen to a highly immunogenic carrier
DNA vaccines
Plasmids carry the genetic information for the antigen

Injection into muscle results in temporary production of the encoded protein.

MHC class I presentation, cell-mediated immunity
Advantages of DNA vaccines
Very stable, safe, & inexpensive to produce
Disadvantages of DNA vaccines
Still a subunit vaccine, risk of transgenesis, public distrust b/c omg science is scary.
Autogenous vaccines
Made from the microogranisms specific to a farm, usually by a licensed facility. Can be used w/ USDA approval on neighboring farms, takes ~ 6 weeks for bacterial vaccines & 12 weeks for viral
Autogenous vaccines are usually...
Killed whole-organism vaccines
Why are autogenous vaccines important for herd health?
Fill a void when new disease agents emerge for which there are no vaccines, or when antigenic variation occurs that is outside the spectrum of protection afforded by commercially available vaccines
Disadvantage of autogenous vaccines
Takes time b/n detecting infection & availability of the vaccination
DIVA stands for...
Differentiate infected from vaccinated animals
Marker vaccines
Typically elicit identical immunity as a live vaccine, but have an additional protein not found on the pathogen or are missing a protein not essential to pathogen growth but recognized by the immune system
Vaccine efficacy
Ability of a vaccine to work as intended to protect from illness
Vaccine-associated risk
Probability of increased adverse events that harm the individual or population
Adjuvant
Substance that enhances the immunogenicity of an antigen
Adjuvants generally work in 3 ways...
Convert soluble proteins into particulate material

Stimulate cytokine production by APC

Depot effect to maintain Ag half life
Why are most proteins poorly immunogenic by themselves?
They are degraded quickly, so don't have enough time to induce a strong B & T cell response
Many vaccines now include ___ that directly stimulate the APC to improve immunogenicity
Cytokines or TLR-agonists
Benefits of adjuvants
Improved immediate response to antigen(s)

Fewer boosters required

Overcome immunosenescence or immunosuppression

Targeting antigens to APC

Activating APC

Improved response to targets w/ low antigenicity
Adjuvants commonly used in vet med (N/A for this exam, but applicable in life)
Mineral salts, immunostimulatory adjuvants, lipid particles, particulate adjuvants, mucosal adjuvants
Advantage of giving vaccines via injection
Ease of anatomic site access
Disadvantages of giving vaccines by injection (5)
Cost of needles

Artificial route of entry for most pathogens

Typically induce primarily IgG responses

Culturally unacceptable in parts of the world

Animal can be difficult to capture
Most pathogens are encountered at...
Mucosal surfaces
Mucosal vaccines improve...
Antigen stability & retention
Advantages of needleless injections for intradermal vaccination
No risk of disease transfer b/n individuals

Better disbursement of antigen

No sharps waste

No risk of needle breakage in carcass

Can be used for any type of vaccine
Disadvantage of needleless injections for intradermal vaccination
More expensive
Factors that contribute to vaccine failure
Presence of maternal Ab

Nature & dose of antigen

Route of administration

Presence of adjuvants

Host factors (age, nutritional factors, genetics, coexisting disease)
Reasons that vaccination can fail (make sure you know a few)
Interference w/ maternal antibodies

Senescence

Improper application of vaccine

Physiologic state of recipient

Host genetics

Pathogen strain antigenic variation

Extremely virulent pathogen strain

Insufficient time for immune response to occur

Poor technique
Principles behind allergy shots
Exposes allergen to immune system in a way that favors IgG production over IgE, usually via adjuvants & changing route of exposure

Induces Treg cells that inhibit allergen-specific B cells & T cells