lec 12-13 vaccines and bioterrorism Flashcards
Jenner 1796
first innoculation
smallpox
major uses of vaccines
domesticated livestock
pets
fish
wild animals
impact of vaccines on smallpox
eradicated
last case 1970s
impact of vaccines on diptheria
very effective
massive/rapid decline in incidence(1950)
impact of vaccines on polio
close to eradication
oral vaccine very effective
aiming to stop transmission e.g. in india
vaccines are not available for ….
malaria
tb
HIV
schistosomiasis
if the body shows natural immunity - recovers and becomes resistant to re-infection…
then it is feasible to devise a vaccine
e.g. polio, smallpox
when is it difficult to devise a vaccine
if the body recovers but is not resistant to re-infection
e.g. HIV, malaria, TB, gonorrhoeae
protective responses -antibodies
proteins that circulate in the blood - produced by B-lymphocytes
orchestrate immune response
bind to toxins, viruses or bacteria
neutralise or promote their clearance
4 types of vaccines
live attenuated
killed
sub-unit
naked DNA
live, attenuated vaccines
living but cannot cause disease
induce variety of immune responses
potential for reversion - virus becomes virulent again
examples of live attenuated vaccines
BCG polio yellow fever typhoid smallpox
why do live attenuated vaccines not cause disease
many reasons not known
some contain mutation in genome preventing them causing disease
how are killed vaccines created
killed by heating or exposure to chemicals e.g. formaldehyde
limitations of killed vaccines
more reactive
dont protect against inhaled infection
never contain V-antigen
killed vaccine
vaccine from dead microorganisms
generally used to provide immunization from organisms that are too virulent to be used in the living state
sub-unit vaccines
fragments of the microorganism e.g. proteins/poysccharides
examples of sub unit vaccines
diptheria
tetanus
anthrax
new plague
formation of subunit vaccines
identify key protective component
isolate genes encoding these components
produce component using genetic engineering
e.g. F1 and V-antigens
advantages of sub-unit vaccines
reproducible
specific - target immune response to specific antigen
not very reactive
pure components - few side effects
disadvantages of sub-unit vaccines
lack of CD8 response
naked DNA vaccines
fragments of DNA - makes protein after injection
process of DNA vaccines
inject piece of DNA that codes for the protein taken up by muscle cells transcribed/translated protein produced by your own cells induction of CD8 T cell response
advantages of naked DNA vaccines
combine advantages from live and sub-unit vaccines
e.g. reproducible, specific etc
work well in mice and horses
what type of vaccine works against West Nile fever for horses
naked DNA vaccine
naked DNA vaccine against fish
used against haematopoetic necrosis
disadvantage of naked DNA vaccines
dont work well in humans
bioterrorism definition
deliberate dispersal of toxic agents to kill man and/or to destroy livestock/crops and disrupt the food chain
biological warfare
used in war against towards armed forces to attack and gain strategic advantages
features of bioterrorism
used against civilian populations
state sponsored or extremist groups
terrorism
key properties of bio-threat agents
potency
cheap
easy to produce
difficult to attribute
potency of bio-threat agent depends on..
infectious dose
airborne stability
what effects airborne stability of bio-threat agent
UV radiation
rainfall
airborne chemicals
temperature
how do you measure potency
relative scale
chlorine is 1
are bio-threat agents cheap
yes
much cheaper that nuclear weapons
are bio-threat agents easy to produce
yes
bacteria are much more simple to culture than viruses
e.g. cultivation of anthrax spores in WWII using marmite, molasses and simple salts
you dont always know if bio-threat agents are an attack
could be deliberate, accidental or naturally occurring
why would smallpox be a good bio-threat agent
infectious virus
lethal
people arent vaccinated against it anymore
why would plague be a good bio-threat agent
very potent bacteria
high mortality rate
good fungi for bio-threat agents
coccidomycosis
wheat stem rust
rice blast fungus
good toxins for bio-threat agents
botulism toxin
ricin toxin
good bacteria for bio-threat agents
anthrax
plague
meliodosis
good viruses for bio-threat agents
smallpox
ebola
inflluenza
1950 treaty
uk signed treaty banning biological weapons
airborne hazard 1981
foot and mouth disease outbreak
plume virus from pig farms in brittany
affected jersey and isle of wight due to prevailing winds
1987 markov assassination
umbrella containing ‘ricin’ causing high fever, gastroenteritis and death
control measures against bioterrorism
prohibition of weapon acquisition and production
defense capability
control export of pathogens, technologies and equipment
security of premises with CL3 and CL4 laboratories
vetting of staff
defence capabilities
detectors and identification equipment
vaccines and treatments for disease
respirators and protective clothing
