Influenza Virus and Vaccine Flashcards
(35 cards)
What are the 3 proteins in the influenza envelope
Hemagluttinin (HA)
Neuraminidase (NA)
Matrix protein 2 (MP2)
What does NA do
cleaves sialic acid which allows virus to leave the cell
WHat does MP2 do?
forms ion channel in endosome allowing the fusion domain of HA to fuse endocytic vesical with viral membrane
Which influenza strains ahve drift and whoch shift?
B, C: only drift
A = drift and shift
What two populations does strain B infect
humans and seals
Which strains cause epidemics
both A and B
WHich strains cause pandemics
A
Strain A infects what types of animals
humans, swine, birds (also marine mammals, bats, horses)
Which strains have NA (thus are susceptible to NA inhibitors
A and B are susceptible
C is not
What are the implications fo being negative sense
it has to package it’s own RNA-dependent viral protease
What populations are more at risk for complicatinos from (7)
DM Obesity Renal Dz Pregnancy Chronic lung dz CVD ASthma
What are the rates of hospitalizations for children who get the flu?
50% are hospitalized w/no comorbidity
Who dies most often from flu
80-90% of deaths are usually people > 65 years old
When is flu season and when is the peak?
Flu season –November through March-peak usually Dec/Jan in U.S.
5 sx of lu
i. Abrupt fever
ii. Myalgia (affecting upper back)
iii. Vomiting/diarrhea- mostly in children
- Non-productive cough (thought to be dt epithelial cell destruction)
- sore throat
How long are adults infectious before and after symptoms appear?
Adults are infectious for 24 hours before symptoms and about 5 days after symptoms
How long are children infectious before and after sx appear?
Children can be infectious for several days before symptoms and shed for 10 days after symptoms.
what 3 cells are destroyed in influenza infx
Productively infects epithelial cells of the respiratory tract (also macros and neutros but non-productive)
why a person is more at risk of bacterial secondary infections with influenza infections. (4)
- ↓ velocity of ciliated clearance = more attachment sites
- viral neuraminidase cleavage of sialic acid–> ↓ bacterial receptor decoy
- ↓ in alveolar macrophages by influenza killing–> decreased clearance of bacteria
- Cells killed by virus provide a rich source of nutrients for bacterial growth!!!
how many deaths in influenza are from bacterial pneumonia?
20-30% of
WHat is the most important Ab to make in influenza infx and why/how?
HA ab- it blocks infx of new cells by neutralizing the virus
Also what viral protein is most important in antigenic shift and drift? and why/how?
HA- can change epitope or mask epitope by glycosylation; this is antigenic drift.
antibodies to NA can also help in infection how?
by blocking the production of infectious particles (block budding and release of the virus).
How does the test detect the flu?
tests for presence of Virus not antibody
