Vaccination

Vaccination

Successful and frequently-used manipulation of the immune system

Routine medical procedure

Provides immunological memory without the infection

Vaccine = non-infectious material with the pathogen’s antigens

Best given in youth to protect the individual and the population

Back to Jenner in late 1700s

First human vaccines were based upon weaker/attenuated viruses

Smallpox vaccine used cowpox

Cowpox virus similar enough to induce an immune response, but did not cause the serious illness of smallpox

Rabies was the first virus that was attenuated in the lab to create a human vaccine

Why was the first vaccine (smallpox) so successful?

Slow virus evolution – epitopes conserved

Live vaccine – impacts skin and is a good mimic of the real infection

Virus cannot survive outside of humans (no animal reservoirs)

Why have we recently seen incidences of cowpox and monkeypox?

Killed or Inactivated Vaccines

Typically use heat or chemicals, like formaldehyde or formalin

Stops pathogen replication but keeps it intact and recognizable

Pros

Cannot revert to a more virulent form

Cons

Shorter length of protection, require boosters

Live, Attenuated Vaccines

Can be made in several ways

Series of cell cultures or animal (chick) embryos

Virus grown in series and becomes better at replicating in non-human host and loses ability to replicate in humans

May require up to 200 passes through non-human host cells

Has potential to revert to a virulent form through mutation

Why oral polio vaccine replaced by the inactivated polio vaccine (IPV) in the U.S.

Inactivated toxins bacterial vaccine

– for bacterial diseases where the toxoids generated by the bacteria cause the illness and not the actual bacteria themselves

Toxoids

Disease caused by the toxin produced by the bacterium and not the bacterium itself.

Ex. Tetanus caused by a neurotoxin produced by Clostridium tetani bacteria

Need to inactivate/neutralize the toxin…turn the toxin into a toxoid (an inactivated protein)

Subunit or Conjugate Vaccines

Both contain only pieces of the pathogens they protect against

Subunit vaccine – isolates one specific piece of pathogen to provoke a response (e.g. flu shot)

May be a recombinant vaccine – made through genetic engineering (e.g. Hepatitis B, HPV)

Conjugate vaccine – similar but a combination of 2 different components of bacterial coats

Components bound to carrier proteins

Small pieces of bacterial coat don’t evoke a strong response, but carrier proteins do

Conjugate vaccines (like for meningitis) will activate BOTH B and T cells! Helps to boost Ab production through plasma cells and TH cells that inspire/support them in the lymph nodes.

Vaccine types

What is an adjuvant?

“Helper” additive

Trigger the innate immune response to start inflammation. The inflammation helps start the adaptive immune response

Allows for a smaller amount of vaccine to produce the same effect.

Herd Immunity