8.3 influenza Flashcards
what type of virus is influenza
segmented -ve ss RNA virus
types of flu viruses that infects humans
3
A,B,C
two viral proteins determining the subtypes of the flu a virus
haemagglutinin (HA)
Neuraminidase ) (NA)
flu A vs flu B
- B most of the time infects human
- B less common than A
- B has one sertotype
glycoprotein for flu C
only has HEF, no HA and NA
symptoms of flu
-fever,
dry cough, gastinointestinal, fatifue
how does flu A enter the cells
HA binds to sialic acid receptor on the surface
- triggers endocytosis of the virus
where can you find the sialic acid receptor
in the respiratory system
how do antibodies fight against the infection of the viruses
- bind to virus so they wont bind to the host cell
- activates complement pathway
- activates phagocytes
when cant antibodies fight against the virus
when the AG is in the host cell
why is the immune responses limited to viruses incl flu
- the AG on virus has variation so infections occur repeatedly
types of AG variation
antigenic drift and antigenic shift
how does AG drift occur
flu virus is -ve virus so uses RdRp
- makes errors due to not ablle to proofread
- accumalate over time
- generate proteins not longer recognised by IS so the previous antibody cant bind to it
how does AG shift occur
- abrupt change where the HA changes
- Ddue to RNA segment of HA being swapped between two viruses in one cell
- resulting in new subtype of HA virus
difference between AG shift and drift
- major vs minor change
- two virus or more needed vs one virus
- rarely vs freq
- large DNA changes vs small mutations
