Vaccines and other Means of Pathogenic Prevention
bed nets, condoms, etc...
The term vaccine, derived from latine for cow, was coined by Pasteur in honour of Edward Jenner's work with cowpox.
Specific Vaccines
- hepatitis A and B
- influenza A and B (trivalent)
- MMR (measles, mumps, rubella)
- pneumococcal vaccine (Prevnar)
- varicella (chickenpox)
- passive immunization
Types of Vaccines
Live vaccines
- Most effective vaccine, made from live pathogens that have been somehow attenuated to make them non-pathogenic
- Effectiveness due to the fact that organism persists for longer periods, and multiple epitopes present
- Can, on rare occasions, revert to become pathogenic again
Live vaccines in use:
- oral polio (primarily in developing countries)
- varicella
- MMR
- yellow fever
- oral typhoid
- BCG against TB; used in confined populations during outbreaks: not 100% effective
Killed Vaccines
- safer, but less effective than live vaccines
- offer many epitopes, in contrast to sub-unit vaccines
Isolated protein vaccines
- well-characterized, customizable
- require adjuvants, such as aluminum, to enhance inflammatory response
- liposomes may circumvent need for adjuvants by enhancing APC uptake
- isolated vaccines essential for immunization against toxins (toxoids), ie tetanus and diptheria
Vector vaccines
- hybrid, using live virus/bacterial vector and inserted gene of interest
- small spectrum of antigens, and disappointing response
Polysaccharide vaccines
- You'd think IgG response requires T cell response and class switch, which occurs only with peptide antigen
- PS vaccines do work over age 3, likely through formation of chimeric haptens
- Conjugated vaccines of capsule proteins for H. influenzae (Act-Hib) and S. pneumoniae (Prevnar) work for infants 2 months and up, through require boosting