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Fall 22: micro > Test 2: orthomyxo > Flashcards

Test 2: orthomyxo Flashcards

1
Q

orthomyxoviridea are —

A

influenza

enveloped
pleomorphic- spherical or filamentous
medium size (120 nm)
large spikes
segmented
negtaive sense
ssRNA

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2
Q

— line the inner surface of the virion envelope of orthomyxovirus

A

M1

Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

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3
Q

what kind of genome does orthomyxoviridae have?

A

segmented negative sense ssRNA

Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

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4
Q

— on viron envelope of flu virus creat ion channels

A

M2

Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

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5
Q

what are the two spikes found on flu A

A

HA- hemagglutinin
NA- neuraminidase

Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

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6
Q

flu A has how many segments of ssRNA

A

8

Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

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7
Q

because fluA is negative sense it brings it own —

A

polymerase

Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

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8
Q

flu A has — genes that create — proteins

A

8
10

Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

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9
Q

how to name influenza virus

A
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10
Q

where do RNA viruses replicate?
what virus is the exception to this rule?

A

cytoplasm

Influenza A

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11
Q

HA protein on flu A will bind to host receptor —- in humans and — in birds

A

2-6 linked sialic acids
2-3 linked sialic acids

Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

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12
Q

RNA replication of flu A occurs in the ___

A

nucleus

different from other RNA viruses that usually replicate in the cytoplasm

Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

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13
Q

Influenza viruses enter cells via —

A

receptor-mediated endocytosis

HA binds to sialic acids (2-6 in humans, 2-3 birds)

Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

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14
Q

how does flu A release genome?

A
  • HA needs to be cleaved by host protease
  • low pH inside the endocytic vesicle allows fusion of HA to endosome
  • change in ion concentration by ion channel M2 will cause M1 to let go of genome
  • will kick out genome that makes its way to the host nuclues

Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

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15
Q

— pH mediated change
of structure in endocytic
vesicle of HA on fluA

A

low

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16
Q

FluA: While in the endosome, the ion
channel — allows the flow of
protons — the virus particle to
enable dissociation of M1 from the
RNP complex.

A

M2
into

Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

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17
Q

—- are antivirals for flu that attack M2

A

M2 inhibitors
M2 are ion channels that change pH inside→cause M1 to let go to viral genome

amantadine and rimantadine

Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

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18
Q

how will fluA initiate mRNA synthesis

A

Flu A- is a negative sense ssRNA
cap snatching: needs to steal 5’ cap from host mRNA to trigger negative sense into positive sense

done by viral endonuclease (PA)

Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

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19
Q

what is cap snatching

A

negative sense Flu2 will use its viral endonuclease (PA) to cleave the 5’cap from cellular mRNA to change negative sense into positive sense

Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

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20
Q

HA on flu A is used for

A

attachment to host cell
fusion to endosome

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21
Q

NA cleaves — from th cell surface to release infectious viruses

A

sialic acid

Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

22
Q

—- (antivirals) limit flu virus spread and reduce transmissibility. They mimic sialic acid.

A

NA inhibitors

23
Q

— are the reservoir hosts of flu A

A

aquatic birds

24
Q

flu viruses replicates where in the body?

A

intestinal and upper respiratory epithelium
excreted in high amounts in feces and oral secretions

25
Q

antigenic drift vs shift

A

drift: small change
shift: reassortment- change in entire gene

26
Q

Small mutations in key proteins that alter antigenicity and/or virulence hat occur over time due to selective pressure and/or mistakes made by the error-prone viral polymerase

A

antigenic drift

27
Q

Major changes by — cause an “epidemic Seasonal Influenza”

A

drift

drift= small mutations

28
Q

Segmented genome allows genomic
segments reassortment. This causes major changes in the subtype. Shifts leads to a pandemic.

A

antigenic shift

why we need new vaccines

29
Q

why are pigs mixing vessels for flu?

A

have 2-3 and 2-6 sialic acid receptors
can bind to avian and human flu
can undergo antigenic shift/reassortment and create completely new subtype

30
Q

— strains of flu can infect pigs, and dual infection may lead to
reassortment and emergence of
new strains.

A

Avian and human

both avian 2-3 and human 2-6 receptors

31
Q

swine influenza causes

A

respiratory disease, high fever and abortions

H3 N2

32
Q

swine flu is spread by

A

inhalation, direct, fomites

H3N2- dogs and pigs and huamns

33
Q

control of swin flu

A

vacccine and biosecurity
can easier transfer from pigs to humans

34
Q

2 types of avian flu

A

low pathogenic avian influenza (LPAI)
highly pathogenic acian influenza (HPAI)

35
Q

symptoms of low pathogenic avian flu

A

ruffled feathers
decreased egg production
can be asymptomatic

36
Q

symptoms of highly pathogenic avian influenza

A

rapid spread- systemic disease and CNS
Fowl plague- visceral necrosis
mortality rate 90-100% within 48 hours

37
Q

the more —- HA= more virulent virus

A

cleavable

if many proteases can cut HA then more viruses will form

Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

38
Q

HPAI contain a polybasic sequence at the cleavage site of HA that allows for intracellular cleavage by —

A

ubiquitous protease →can effect different organs and systems, leads to systemic infections and death

highly pathogenic avian influenza

39
Q

LPAI contain a —- cleavage site on the HA.

A

monobasic

low pathogeic avian influenza

40
Q

what types of HA are usually pathogenic?

A

HA 5
HA 7

has enhanced cleavability

HA found on surface of flu virus

41
Q

difference between LPAI and HPAI

A

LP- will have only host proteases from the respiratory tract that can cleave the HA protein

HP- will have multiple basic residues at the cleavage site to allow for many different proteases to cleave HA protein

42
Q

— is equine flu

A

H3N8
argentinean, florida and kentucky

can spread to dogs

H7N7 no longer exsist

43
Q

transmission of equine flu —

A

Highly contagious by aerosol droplets;
inhalation, direct, fomites.

44
Q

symptoms of equine flu

A

Harsh, dry cough for ~3 weeks, high morbidity, reddened nasal mucosa, conjunctivitis, serous to mucopurulent discharge, fever, inappetence.

45
Q

H3N8

A

equine flu
can spread to dogs

cause respiratory tract disease

46
Q

canine flu symptoms

A

Respiratory tract disease (coughing,
sneezing, nasal discharge, fever),
secondary bacterial infections. Often
mistaken for kennel cough.

supportive care

H3N2- birds→dogs

H3N8- equine →dogs

47
Q

diagnosis of canine flu is by

A

reverse transcriptase PCR
will determine the H/N subtype and culturered for antigenic analysis

48
Q

The role of — in the release of the progeny flu viruses and the spread of the virus from the host cell to uninfected surrounding cells

A

neuraminidase
(NA)

49
Q

Describe the structure of influenza A (orthomyxovirus) virus

A

negative sense
segmented(8) ssRNA
enveloped with HA and NA spikes
M2 forms pores
M1 lines inside

50
Q

What are the different avian influenza subtypes that have
high tendency to mutate to HPAI?

A

H5 H7

51
Q

What strains/subtype of equine influenza is currently circulating in the USA?

A

H3N8
H7N7- extinct

52
Q

What are the clinical signs of swine, horse and canine influenza viruses?

A

swine: H3N2- Respiratory disease and abortions, high fever
5-7 day course

horse: H3N8 dry cough for 3 weeks, nasal discharge, conjunctivitis, fever

dog: H3N8 and H3N2- cough, sneezing, nasal discharge and fever. looks like kennel cough

Fall 22: micro (25 decks)

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