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MICR2222 medical virology > influenza the virus life cycle lectures 1 and 2 > Flashcards

influenza the virus life cycle lectures 1 and 2 Flashcards

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USMLE® Step 1 flashcards
1
Q

how is H5N1 influenza virus spread

A

by bird migration

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2
Q

what does it mean by negative sense strand

A

is complementary to the positive strand and doesn’t code for proteins they have no useful ORFs

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3
Q

how can negative strands become useful

A

must be transcribed to positive sense copies

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4
Q

what are the genome segments assembled into

A

ribonucleoproteins or RNPs

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5
Q

what are the 3 parts to the segment

A

lopped end, central filament region, RNA polymerase end.

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6
Q

what hapeens to the 2 ends in the RNP

A

they are forced together and bend into a hairpin shape.

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7
Q

how are the ends held together

A

watson-crick interactions or ends can interact with complex of 3 protiens called the RNA-dependent RNA polymerase .

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8
Q

What does the nucleoprotein NP do

A

forms a chain to entirely cover the RNA

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9
Q

what does chain formation depend on

A

the NP-NP interaction through the tail loop and the RNA binding in a groove on the NP surface.

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10
Q

which proteins are needed for RdRp

A

PB1, PB2, PA

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11
Q

what is the matrix protein needed foR

A

structure, shape M2 protein, ion channel.

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12
Q

what is NS1 needed fot

A

IFN antagonist, RNP epxort

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13
Q

what is NS2 needed for

A

RNP export

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14
Q

how is sialic acid related to galactose

A

has either 2-3 or 2-6 alpha linkage

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15
Q

what cell type linkage does human flu moslty infect

A

2-6

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16
Q

whta is HA initially synthesised to

A

HA0

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17
Q

what is HA0 cleaved to

A

HA1 AND HA2

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18
Q

what is cleavage done by

A

proteases e.g furin

19
Q

what do HA1 and 2 form

A

1 forms the globular head and 2 forms the long stalk via a 6 helix bundle. receptor binding site is in HA1 domain.

20
Q

how does the fusion peptide become active

A

it is re positioned from in HA0 to the amino terminus. done when HA 1 and 2 are cleaved.

21
Q

what triggers conformational chnage exposing fusion peptide

A

ph5 this aligns HA2 and peptide goes upwards and inserts into endosome membrane

22
Q

what are the 2 critical functions of HA

A

1-virus attachment
2-virus entry

23
Q

what is M2

A

a viroporin allows release of RNP

24
Q

what other factors does RNP release need

A

EPS8, TNP01, HDAC6

25
Q

what doe individual NPmonomers have

A

2 import signals

26
Q

what is exposed in formed RNPs

A

NLS1

27
Q

what does NLS1 do and lead to

A

recruits importin alpha then beta importin is recruited. RNP/importin complex binds pore and the RNPs enter the nucleus

28
Q

what does trnascription result in

A

generation of one RNA trnascript per segment

29
Q

what is the 1st stage of transcription

A

RdRp PB2 binds to mRNA and PA steals the 5 cap

30
Q

what is the 2nd stage

A

RdRp and capped oligonucleotide bind to negative strand RNA genome

31
Q

what is the 3rd stage

A

RdRp PB1 uses capped RNA to begin transcription

32
Q

what is the 4th stage

A

RdRp moves along the template, PB1 geberates RNA trnacript with 5 cap and 3 poly A tail.

33
Q

what is the fate of Influenza mRNA and their products

A

HA, NA, M2 NS1 stay in cytoplasm for assembly.
NP, PB1, PB2, PA, M imported to nucleus to make more RNPs

34
Q

what is the 1st stage of replication

A

RdRp binds 3 end of RNA segment no primer

35
Q

2nd stage of replication

A

RdRp travels to 5 end make complementary copy.

36
Q

3rd stage of replication

A

NP wraps RNA as it’s made

37
Q

4th stage of replication

A

cycles of replication allow amplification of genomes.

38
Q

what does NS2 do

A

binds M forms outer layer on RNP has an export signal that masks all other signals.

39
Q

what does CRM1 do

A

allows NS2 to engage host cell machinery for export. It binds to Ran-GTP and exits NPC.

40
Q

what needs to reach the apical surface of the plasma membrane

A

all 8 segments and HA, NA, M1 and M2

41
Q

how ae HA, NA and M2 trafficked

A

via secretory pathway

42
Q

how are the RNPs abd M1 trafficked

A

on recycling endosomes. RNP interacts with Rab11.

43
Q

what does M1 associate with

A

cytoplasmic tails of HA, NA, and M2

MICR2222 medical virology (9 decks)

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