10 - vaccines 1 Flashcards
most widely used vaccines
bacterial
jenner 1796
forefather of vaccinology
benefical impact of vaccines
save 2.5 million lives a year
4 main types of vaccine
live attenuated
killed
sub-unit
naked DNA
live attenuated vaccines
alive but cannot cause disease unless immunosuppressed
used to be most common
killed vaccines
kiled by heating or exposure to chemicals
sub-unit vaccines
isolated fragments of micro-organism
e.g. an individual protein/polysaccharide
becoming most common
can be single sub unit or multiple sub unit vaccines
naked DNA vaccines
dna injected
makes proteins in the body
immunity induced by sub unit vaccines
antibody-mediated immunity
which initiates protective mechanisms
corynebacterium diptheria bacteria
carried in the throat then no disease
produces potent toxin that blocks protein synthesis and causes heart failure
vaccine against corynebacterium diptheria bacteria
neutralises toxin
treated with formaldehyde
very effective
formaldehyde detoxification
works by cross linking the protein via amino groups
inter and intra molecular linking changes structure so it can no longer exert toxic action
advantages of formaldehyde detoxification
toxicity of protein abolished
immunogenecity of protein preserved so it is still recognised by the immune system
disadvantages of formaldehyde detoxification
too much cross linking and then it can no longer be recognised by the immune system
batch to batch variation
chances of reversion
purifying and handling of toxin required
genetic toxoids
genetically engineer/modify toxin so it is non-toxic but retains immunogenecity
diptheria genetic toxoids CRM197
mutate catalytic A subunit to block activity
glycine substitution
looks identical to original toxin
necrotic enteritis toxoid
toxins perforate gut wall so cell cannot regulate osmotic balance
identify amino acids necessary for toxicity in Net B toxin
advantages of genetic toxoids
cheap and easy to produce safe reproducible no reversion molecular structure more similar to active toxin
plague
caused by bacteria yersimia pestis
two important components (F1 and V antigen) combine to create solid protection for bacteria
F1 antigen
plague bacteria component
forms capsule around bacterium to protect
V antigen
part of plague bacteria T3SS
molecular syringe in cell wall
reverse vaccinology
take genome sequence from microorganism
predict which proteins (often surface proteins) would be effective for inclusion in the vaccine
technology used = pSORT
neisseria meningitidis B
causes 135,000 deaths per year
reverse vaccinology being used as traditional vaccinology failed
serogroup B strains being used
method of reverse vaccinology
develop list of proteins to test
shortlist them and confirm
pSORT
computer progam that predicts cellular location of proteins in cells
