respiratory viruses Flashcards
fomites
inaminated object contaminated with secretions containing viruse
influenza incubation and contagion
incubation is 1-3 days and a person is contagious from 1 day to 7 days after the onset of symptoms
influenza description
negative sense single stranded RNA with 8 segments
important influenza proteins (3)
- RNA pol- genome replication and transcription
- HA- binds cell receptor and fuses envelope with the cell membrane
- NA- helps release virions from cells surface after budding ** antiviral target
antigenic drift
epidemic
antigenic shift
pandemic
small antigenic changes in the virus
antigenic drift
large antigenic changes in the virus
antigenic shift
Type A influenza
both epidemics and pandemic
***migratory acquatic birds are the reservoir
A/california/7/2009 (H1N1)
type/location of the outbreak/strain/year of the outbreak (subtype)
how does the antigenic drift occurs?
viral RNA pol is error-prone- makes mistakes and does not correct them
how does antigenic shift occurs?
exchange (reassortment) of genome segments between avian and mammalian viruses - only in type A
different cell receptors between human and bird flu?
Human HA binds to alpha-2,6-sialic acid while bird flu HA binds to alpha-2,3- sialic acid
what about the HA targets of pid?
have both sialic acid receptors
concern for the reassortment of bird and human flu
results in a highly contagious and virulent strain
