RNA viruses (Influenza) Flashcards
what is the biology of Influenza A/B/C virus?
enveloped single stranded RNA segmented
what is the worst influenza virus?
type A
what influenza virus type is the mildest?
B and C
influenza A/B/C belongs to what virus family?
orthomyxo family of viruses
what enzyme do single stranded -RNA carry around for replication?
RNA Dependent RNA Polymerase (RDRP)
what is the mechanism used for replication in single stranded -RNA?
-RNA genome transcribed to mRNA and then a full +RNA using RDRP
how many segments does influenza A/B/C have?
8
what is characteristic about the influenza envelope?
it has spikes made of Haemagglutinin and Neuraminidase
what is the clue to determine what influenza strand is which (A/B/C)?
looking at the envelope for Neuraminidase protein
or
at the matrix for M1 or M2 protein
what determines the sub-types of influenza A/B/C?
Hemagglutinin
Neuraminidase
what is important about the M2 protein found in influenza?
1) they form proton channels in the membrane
2) promote uncoating and viral genome release
what inhibits the function of the M2 protein in influenza?
amantadine
remantandine
what does influenza use to bind to RBC’s?
haemagglutinin
the VAP of influenza will bind to epithelial cells using what receptor?
sialic acid receptors
what mechanism is used to protect the cell from the influenza VAP?
neutralization by using antibodies
what is the purpose of the neuraminidase enzyme in influenza?
it releases the mature virus from the cells
what drugs are used to target neuraminadase in influenza?
Zanamivir
Oseltamivir
how is influenza transmitted?
aerosol
during what months is it mostly common?
during winter
Influenza type A is found in what animal?
birds, human, pigs
influenza type A will spread using what mechanims?
antigenic shift (causes pandemics) and antigenic drift (causes localized epidemics)
in what species is influenza B and C found?
only in humans
influenza type B and C undergoes what type of epidemiology?
antigenic drift only (causes localized epidemics)
what is an antigenic drift?
accumulation of point mutations causing changes in Neuroaminidase and Haemagglutinin
what is antigenic shift?
acquiring completely new haemagglutinin and neuroaminidase proteins from gene re-assortment
what facilitates antigenic shift in influenza type A?
ability to infect human and animal species causing their RNA segmenst to mix
where will influenza generally establish the infection?
in the upper and lower respiratory tract
when are systemic symptoms in influenza seen?
when interferon and lymphokine respond to the virus
what is needed to resolve infection by influenza?
cell mediated immunity and interferon
death by influenza is most common by what?
opportunistic infections,
specifically Staph. aureus
when there is a antigenic drift, what immunity will we have?
we will have only partial protection
if there is a antigenic shift, what immunity will we have?
the population is completely susceptible
what are the clinical signs seen in influenza?
high fever
chills
myalgia
fatigue
sore throat
what will influenza cause in kids under 3 y/o?
Upper and lower Tract infection
croup
vomiting
what are the complications that can occur in influenza infection?
1) viral pneumonia (Acute Resp. Distress Syndrome)
2) 2ry bacterial pneumonia (S.Aureus)
3) Myositis (kids)
4) Reyes Syndrome (aspirin administration to children)
5) Guillain-Barre Syndrome
what is the most common cause of death in the elderly with Influenza?
2ry bacterial pneumonia
what is used to treat influenza?
how are these administered and when?
rimantadine and amantadine
zanamivir and oseltamivir
they must both be administered early after exposure
how is influenza prevented?
inactivated vaccine (flu-shot)
and live attenuated strain (flu-mist)
what strains does the inactivated influenza vaccine have?
type A and B
what causes the need for a new shot every year?
antigenic drift
