Vaccines Flashcards
What are typically the purpose of vaccines?
Primarily Prevent Symptoms
– more uncommonly elimination of the disease
What kind of virus properties make it a target for vaccine?
- serious infection/long term effects
- limited serotypes
- slow mutation rate
- life long immunity after infections
What are considerations when developing a vaccine?
- long acting immunity, must not cause illness or treat to contacts
- cost - shelf-life
- ease of distribution and administration
- limited side effects
- size of market for use
What is the main goal of a vaccine?
To generate neutralizing antibodies
- prevent viruses from invading healthy cells
- promotes virus destruction
- activates complement
- targets infected cells, marking them for destruction
What are antibodies made to against the virus?
- repeatitive surface antigens are best for neutralizing antigens
What kind of antibody protection is the best to acquire via vaccine?
Mucosal Immunity - IgA
- target antigens at the portal of entry
What are the benefits of the inactivated (Salk’s) polio vaccine?
- Safe for immunocompromised individuals
- Unable to mutate into virulent form
What are disadvantages to the innactivated polio vaccine?
- fails to elicit gut / mucosal immunity
- requries IM / IV injection
- expensive, multiple boosters
- must ensure antigen inactivation
What are the biggest problems with inactivated virus vaccines?
- must ensure inactivation
- circulating antibodies, not mucosal
- can elicit unbalance antibody response
*Longivity of response is unknown
Benefits - Avoids risks of attenuated virus vaccines
What are the advantages to live attenuated vaccines? (Sabin)
- inexpensive
- induces both systemic and secretory immunity
- allows herd immunity
- full range of gene products/antigens to present to immune system
Disadvantages of using live virus vaccine?
- chance of virus mutating into virulence strain
- less reliable in tropical climate due to vaccine needing to stay cold
- subject to viral immune evasion strategies
- can possibly spread from individual recently vaccinated
How did Sabin create a viral strain that was less virulent in humans for his live virus vaccine?
Let the virus grow in another species, so that it acquires mutations beneficial for virulence in that species, but loses specificity to humans. Thus less virulent in humans, yet has a chance to revert back.
How does recombinate or subunit viruses work in establishing immunity?
Genetically alter a virus by adding in antigenic genes from another, but making them less virulent, so you can get double immunity from a single vaccine. Produces the antigenic proteins.
What are the pros/cons of a subunit vaccine?
- production costs would be higher
- would not have to worry about inactivation of the live virus
How does DNA inoculation work?
DNA that encodes antigens can be injected directly into tissues that can benefit from the immunity.
