Vaccination, immunity & drug development 4.1.1
Vaccination
artificial immunity - deliberate exposure to antigens in order to provide immunity trying to produce memory cells
antigenic material
2) harmless or attenuated microbe
3) a dead pathogen
4) just the antigens
5) injected with a toxoid
1) a whole live microbe
has similar antigens
e.g. cow pox
e.g. measles or TB
e.g. typhoid or cholera
e.g. hepatitis B
harmless version if the toxin
e.g. tetanus
applications of vaccines
herd vaccination
ring vaccination
vaccinating all the population at risk, stops spread
e.g. small pox --> 80-85% of population
ideal: 95%
for new reported cases
all in immediate vicinity are vaccinated
some pathogens are very unstable & frequently mutate; e.g. influenza (changing antigens. - new strains must be monitored
Influenza
killer disease for over 65 group
in 1918 an epidemic killed 40 million people
in 1968-69 1 million people were killed in Hong Kong
a world wide epidemic is called a pandemic
in UK there's a programme to vaccinate all over 65s - 73% of them end up vaccinated - younger groups only 52%
4 types of immunity
2) active artificial
3) passive natural
1) active natural
4) passive artificial
immunity is provided by antibodies by your immune system as a result of infection, e.g. chicken pox
immunity provided by antibodies provided by your immune system as a result of vaccination, e.g. TB vaccine
a human receives antibodies in a natural way - antibodies provided by breast milk - useful for 1st few days, quick short term protection but doesn't last very long
immunity provided by injection of ready made antibodies, e.g. hepatitis A & B
drug development (how new medications are discovered)
observation
isolating chemicals
traditional medicine
disease-causing mechanisms
accident
genomic medicine
Fleming & penicillin, the fungi penicillium releases compounds which kill bacteria (antibiotic)
have been used for centuries, 80% of world population relies on traditional medicine
in India 7000 different plants are used in medicine
morphine is derived from poppy seeds, anaesthetic stops pain signals
willow bark stops pain & fever but causes stomach to bleed so late modified chemical to make aspirin & ibuprofen added acetyl group to it
monkeys & bears rub citrus in their coats as insecticides
birds line nests with medicinal leaves to protect chicks from mites
the active ingredients in plants can be concentrated & purified & similar compounds can be made
HIV binds to receptors on T helper cells, so scientists look for drugs that mimic the receptors & binds to he virus
tailor made for people based on their DNA profile
Antibiotic resistance
many strains of bacteria are resistant to penicillin case they produce beta-lactamase enzyme
beta-lactamase breaks sown the penicillin molecule
resistance is cause by mutations
mutations can code for a new substance which can destroy or inactivate an antibiotic
Auto-immune diseases
happen when the antigens on our own cells are misrecognised & are attacked
e.g. arthritis & lupus