Immunisation Flashcards
Benefits of vaccination
Individual and population effect
I = immunity to infection P = Reduced transmission of infection + reduced disease in vaccinated and unvaccinated people = herd immunity
What are the types on antigens that we generally make antibodies against?
Protein antigens - T cell dependant antibodies
Polysaccharide antigens - T cell independant antibodies
Live viral vaccines
- antibodies, CD8 cytotoxic cells
Live viral vaccines
Live viruses or live bacteria
Not pathogenic, won in culture under various conditions to change their pathogenicity whilst retaining their antigenicity
“attenuated” vaccines
Inactivated vaccines
from early in the 20th century
Whole viruses, bacteria or fractions
Chemically inactivated
Now days is much better to look for key antigens / epitopes on an organism and present them to the immune system
Protein based vaccines: toxoids (inactivated bacterial toxin), subunit or subversion
Polysaccharide based vaccines doesn’t produce good immunity, so they’re often chemically conjugated to an immunogenic protein which serves as a carrier and stimulates a much better longer lasting immunity against a polysaccharide
Live vaccines
Modify virus or bacteria in a lab
Replicate and produce immunity but not illness
Generally lifelong immunity
They actually generate an immune response??
e.g. VIRAL measles mumps, rubella, varicella, oral polio vaccine
BACTERIAL: BCG (tuberculosis), oral typhoid vaccine
REASSORTED: rotavirus vaccine (Rotateq) (they’ve engineered specific genes into the capsid of a rotavirus, so theres a lot of different epitopes that are being responded to)
Can cause problems in immunocompromised people
Inactivated vaccines have been? is this good or bad for long term immunity?
Not lifelong immunity with one dose, because they can’t replicate so need to gives heaps of doses to produce enough antibody and sufficient B cell memory (repeat immunisation nessecary)
Examples of whole viral vaccines
Influenza, injected polio, rabies and hep A
Examples of whole bacterial vaccines
Pertussis, typhoid, cholera
Examples of fractional vaccines
subunits (hep B, influenza, acellular pertussis)
Toxoids, which have been purified to retain antigenic shape but lose their toxicity (diphtheria, tetanus)
The difference in dosing between whole live organisms vaccine dose VS killed or components of organism vaccine dose
Need to give more doses (at least 3) with the latter type because they lack the capacity to replicate and so therefore cant imitate as strong an immune response on the same injection amount
Hepatitis B recombinant vaccine: explain
segment of HBV gene into yeast expression system
Vaccines given earlier in life are different in what way?
Manly antigenic fragments, don’t need a super well developed immune system to be received, whereas the ones which imitate a lifelong immunity need to be given when you’re older and have a stronger immunity, also by this time you would know if the child had some sort of immunodeficiency
What is the Infeanrix-hexa vaccine?
6 vaccines in one injection: diphtheria, tetanus, acellular pertussis, inactivated polio, haemophilia influenzae type B, hepatitis B
All are component antigen vaccines
Given at 6wks, 3 and 5 months and 4 years
When is the MMR vaccine given?
Later than the 6 vax one because they’re all live viruses and you need to be sure patients immune system is sound
15months, 4 years
Tetanus
Clostridium tetani: anaerobic, spore-forming, gram postive bacillus, penicillin sensitive
Spores everywhere particularly manure/ soil
Easily induced at time of injury, especially deep penetrating dirty wounds
Toxin symptoms:
- about 10 days after exposure of a wound to dirt or soil
Clinical features: arching of back (opisthotonus) facial grimace (rises sardonicus) ‘lock jaw’
