RNA viruses (Influenza) Flashcards

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1
Q

what is the biology of Influenza A/B/C virus?

A

enveloped single stranded RNA segmented

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2
Q

what is the worst influenza virus?

A

type A

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3
Q

what influenza virus type is the mildest?

A

B and C

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4
Q

influenza A/B/C belongs to what virus family?

A

orthomyxo family of viruses

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5
Q

what enzyme do single stranded -RNA carry around for replication?

A

RNA Dependent RNA Polymerase (RDRP)

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6
Q

what is the mechanism used for replication in single stranded -RNA?

A

-RNA genome transcribed to mRNA and then a full +RNA using RDRP

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7
Q

how many segments does influenza A/B/C have?

A

8

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8
Q

what is characteristic about the influenza envelope?

A

it has spikes made of Haemagglutinin and Neuraminidase

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9
Q

what is the clue to determine what influenza strand is which (A/B/C)?

A

looking at the envelope for Neuraminidase protein

or

at the matrix for M1 or M2 protein

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10
Q

what determines the sub-types of influenza A/B/C?

A

Hemagglutinin

Neuraminidase

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11
Q

what is important about the M2 protein found in influenza?

A

1) they form proton channels in the membrane
2) promote uncoating and viral genome release

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12
Q

what inhibits the function of the M2 protein in influenza?

A

amantadine

remantandine

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13
Q

what does influenza use to bind to RBC’s?

A

haemagglutinin

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14
Q

the VAP of influenza will bind to epithelial cells using what receptor?

A

sialic acid receptors

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15
Q

what mechanism is used to protect the cell from the influenza VAP?

A

neutralization by using antibodies

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16
Q

what is the purpose of the neuraminidase enzyme in influenza?

A

it releases the mature virus from the cells

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17
Q

what drugs are used to target neuraminadase in influenza?

A

Zanamivir

Oseltamivir

18
Q

how is influenza transmitted?

A

aerosol

19
Q

during what months is it mostly common?

A

during winter

20
Q

Influenza type A is found in what animal?

A

birds, human, pigs

21
Q

influenza type A will spread using what mechanims?

A

antigenic shift (causes pandemics) and antigenic drift (causes localized epidemics)

22
Q

in what species is influenza B and C found?

A

only in humans

23
Q

influenza type B and C undergoes what type of epidemiology?

A

antigenic drift only (causes localized epidemics)

24
Q

what is an antigenic drift?

A

accumulation of point mutations causing changes in Neuroaminidase and Haemagglutinin

25
Q

what is antigenic shift?

A

acquiring completely new haemagglutinin and neuroaminidase proteins from gene re-assortment

26
Q

what facilitates antigenic shift in influenza type A?

A

ability to infect human and animal species causing their RNA segmenst to mix

27
Q

where will influenza generally establish the infection?

A

in the upper and lower respiratory tract

28
Q

when are systemic symptoms in influenza seen?

A

when interferon and lymphokine respond to the virus

29
Q

what is needed to resolve infection by influenza?

A

cell mediated immunity and interferon

30
Q

death by influenza is most common by what?

A

opportunistic infections,

specifically Staph. aureus

31
Q

when there is a antigenic drift, what immunity will we have?

A

we will have only partial protection

32
Q

if there is a antigenic shift, what immunity will we have?

A

the population is completely susceptible

33
Q

what are the clinical signs seen in influenza?

A

high fever

chills

myalgia

fatigue

sore throat

34
Q

what will influenza cause in kids under 3 y/o?

A

Upper and lower Tract infection

croup

vomiting

35
Q

what are the complications that can occur in influenza infection?

A

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

36
Q

what is the most common cause of death in the elderly with Influenza?

A

2ry bacterial pneumonia

37
Q

what is used to treat influenza?

how are these administered and when?

A

rimantadine and amantadine

zanamivir and oseltamivir

they must both be administered early after exposure

38
Q

how is influenza prevented?

A

inactivated vaccine (flu-shot)

and live attenuated strain (flu-mist)

39
Q

what strains does the inactivated influenza vaccine have?

A

type A and B

40
Q

what causes the need for a new shot every year?

A

antigenic drift