vaccines Flashcards
(48 cards)
what are the 3 types of traditional vaccines
whole killed
toxoid
live attentuated
2 types of immunisation
passive
active / vaccination
define passive immunisation
the administration of pre formed ‘immunity’ from one person or animal to another person
limitation of passive immunisation
only humoral (antibody) mediated
not work if cell mediated
advantages of passive immunisation
gives immediate protection
effective in immunocomproised patients
disadvantages of passive
short lived
possible transfer of pathogens
‘serum sickenss’ on transfer of animal ser
2 examples of passive immunisation
Human Normal Immunoglobulin (HNIG)
Convalescing serum eg SARS Co-V2
how is HNIG prepared
from pools of of at least 100 donors
contains antibody against measles, mumps, varicella, hepatitis A etc
how is convalescing serum prepared
pooled from people recovering from covid -19
but clinical trial result sugggests no overall increased efficiacy against virus using passive immunisation
what was he first ever vaccine against
small pox
3 main approaches to making a vaccine
- using a whole virus or bacterium
- using parts that trigger the immune system
- using just the genetic material
2 different types of vaccines
non living vaccines - whole killed and toxoids
l;i’ve attentuated vaccines
what is the whole microbe vaccine approach
inactivated vaccine
live attentuated vaccine
viral vector vaccine
how are bacteria and viruses inactivated
they are grown in vitro and inactivated using agents such as formaldehyde or B-proplonolactone
do non living vaccines cause infection
no but the antigens contained in it induce an immune response that protects against infection - by non self antigen recognition
non living vaccines can also be cell freee toxoids - inactivated toxins
problems and limitations of whole killed vaccines
The organisms must be grown to high titre in vitro (viruses and some bacteria difficult/expensive to grow in the lab)
• Whole pathogens can cause excessive reactogenicity (i.e., adverse reactions, excessive immunological responses)
• Immune responses are not always close to the normal response to infection, e.g., no mucosal immunity, no CD8 Tc responses
• Usually need at least 2 shots
4 examples of bacterial whole killed vaccines
diptheria
tetanus
pertussis
cholera
examples of viral whole killed vaccines
polio vaccine
influenza vaccine
hepatitis A vaccine
rabies vaccine
SARS - COV 2
what are live attentuated vaccines
The organisms replicate within the host and induce an immune response which is protective against the wild-type organism but does not cause disease.
benefits of live attenuated vaccines
more real life and provides better protection
Immune response more closely mimics that following real infection because its not fixed – no shape change.
Better immune response so lower doses are required, so the scale of in vitro growth needed is lower.
Route of administration may be more favourable (oral).
Fewer doses may be required to provide protection.
what is attenuation
where an organism is cultured in such a way that it does not cause disease when inoculated ito humans
it has lost its pathogenicity but retains its antigenecity ie shape
problems and limitations of live attenuated vaccines
often impossible to balance attenuation and immunogenicity
reversion to virulence
transmissibility
live vaccines may not be attenuated in immunocompromised hosts
examples of bacterial live attenuated vaccines
- Bacille Calmette-Guérin (BCG) Mycobacterium bovis grown over many passages in vitro.
Gives some protection against TB (tuberculosis) - Salmonella typhi - temperature sensitive strain given orally.
examples of viral live attenuated vaccines
poliomyeletis (SABIN)- widely used to brain g polio to extinction
vaccinia virus - used in billions of doses to eradicate smallpox
measles, mumps, rubella - MMR
