Vaccination Flashcards
it is the advent of __________ that allows us to control timing of exposure to pathogens and deliver them when its safest with a form that is least likely to cause natural disease symptoms yet provides everlasting protection
vaccines
vaccination involves:
giving antigen derived from an infectious agent to an animal so that an immune response is mounted and resistance to that specific infectious agent is achieved
we can effectively present antigen to the immune system by:
(live, modified live, killed, or engineered)
natural immunity
disease from being exposed to it in the environment, the body has an opportunity to create antibodies and memory B and T cells, which provide a defence against any subsequent exposure to the disease
artificial immunity
selecting succcesful vaccination
The absolute identity of the organism causing the problem?
That the immune process does not contribute to the disease process?
That immunity can be induced?
That the risk of vaccination does not exceed the risks associated with contracting the disease?
methods of passive and active immunization
Passive immunity:
- Maternal—via placenta or colostrum fresh from a dam (their mother or a foster), or frozen
- Artificial—hyperimmune serum (from animals already vaccinated or previously exposed to the disease)
- Monoclonal antibodies (manufactured in lab from a hybridoma)
Active immunization:
- Natural active immunity—infection
- Artificial active immunity—vaccination
new generation vaccine production technologies
exposure to a small amount of actual antigen (like historic variolation) or, more currently, vaccines may be created using any of the following products to stimulate an immune response:
Metabolic products (e.g., tetanus toxoid)
Dead organisms called bacterins
Living organisms
Full virulent (fully live!!)
Heterologous (e.g., measles and canine distemper) that provide cross protection
Attenuated or modified live (MLV) (e.g., distemper)
Genetically engineered “recombinant” technology vaccines
Non-infectious sub-unit vaccines
Gene-deleted vaccines
Vectored vaccines
Synthetic antigens
purpose of adjuvants and limitations
Anything which increases efficacy and/or potency is an adjuvant.
how vaccines are attenuated
live modified
- uses a similar virus (heterologous) from another animal species (cowpox and smallpox)
- Pathogen is grown in an “un-natural” host or cell culture for multiple generation
inactivated/dead:
- Exposure to heat or chemicals is commonly used to create killed vaccines. Too much, and the vaccine will lose its immunogenicity, but not enough and the vaccine will still be pathogenic!
-“Killed” vaccines generally need the addition of an adjuvant to increase their immunogenicity. Killed vaccines also need a larger volume of particles to be administered to have an adequate immune response.
Killed vaccines have been improved so that there is higher antigenic mass with more effective adjuvants available.
causes of failure of vaccination, host related factors:
Ineffective vaccine: The wrong strain or antigens for the disease may be in the vaccine.
Unsatisfactory administration (especially aerosol or drinking water administration): While these routes can be very cost effective, it is possible that not all animals will receive an adequate dose due to individual animal habits, or dissemination of the vaccine.
Vaccine died: This may be due to poor storage of the modified live vaccine (temperature fluctuation), or chemicals may have been used to clean the needle and syringe.
Already incubating disease: The animal may have already been ill and not showing signs. It is too late to stimulate an immune response if the animal already has contracted the disease. (Canine parvovirus is a “classic” in this regard.)
Fails to mount an immune response:
adverse consequences of vaccination and how to avoid them
- Residual virulence and toxicity can occur. This is mostly an issue for modified live vaccines.
- Allergic effects/reactions can occur
- Disease can be caused in immunodeficient hosts (disease starts after vaccine).
- Harmful effects on the fetus such as abortion or teratogenic effects can occur (teratogens halt the pregnancy or produce a congenital malformation
- complications can occur by provoking an autoimmune disorder: autoimmune thrombocytopenia, autoimmune hemolytic anemia, and autoimmune joint diseas
the ideal vaccine:
- Promote resistance to disease.
- Stimulate long-lived immunity to the recipient and any fetus it may carry.
- Remain stable at room temperature for a prolonged period.
- Be safe, eliciting minimal/acceptable side effects.
- Be inexpensive.
- Stimulate an immune response distinguishable from natural infection so you can vaccinate and eradicate simultaneously.
living organism vaccines
stimulate the best and most complete immune response but present hazards because of residual virulence (ability to cause disease). They can also make it difficult to distinguish between the immune response from having the disease vs. that from a vaccination. New methods of testing to differentiate are being developed for diseases such as Lyme disease and foot and mouth disease.
