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Microbiology 2 > Lecture 16: Orthomyxoviruses > Flashcards

Lecture 16: Orthomyxoviruses Flashcards

1
Q

What is the major genera of virus that is in orthomyxoviridae family

A

influenza A, B, C, D- influenza A most common

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2
Q

what is reservoir host for orthomyxoviridae/ influenza viruses

A

aquatic birds

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3
Q

what type of genome structure does influenza A have

A

segmented - sense ssRNA

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4
Q

influenza A viruses are subtypes based on ___

A

hemagglutinin and neuroamindase surface glycoproteins

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5
Q

what Baltimore classification are influenza A viruses

A

group V

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6
Q

What is pathogenesis for influenza A virus replication

A
  1. HA binds to sialic acid on host cells
  2. Receptor mediated endocytosis
  3. HA permits release of viral RNA into cells
  4. Synthesized HA0 precursor cleaves into HA1 and HA2 necessary for conformational change that allows virus to merge with host membrane
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7
Q

what is HA necessary for in influenza A virus

A

attachment and fusion of viral and cellular membranes- permitting release of viral RNA into cell

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8
Q

what is key virulence factor of Influenza A

A

cleavage site

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9
Q

what is monobasic influenza virus cleaved by and what tissues affect

A

cleaved by trypsin like proteases and only goes to limited tissues

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10
Q

what is multi basic influenza A virus cleaved by and what tissues infected

A

furin like proteases and faciliates systemic replication in chickens- can infect all tissues

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11
Q

avian influenza viruses exhibit greatest biodiversity with __HA genes and __NA genes

A

16, 9

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12
Q

how do migrating water fowl spread influenza

A

excrete virus in feces which is spread by fecal-oral route

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13
Q

what is antigenic drift

A

minor changes in HA or NA, seasonal changes

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14
Q

antigenic drift is accumulation of __due ton low fidelity of RNA-dependent RNA polymerase causes ___

A

random point mutation, antigenic drift

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15
Q

how does antigenic drift affect vaccines

A

may prevent binding of neutralizing antibodies to HA, necessitating annual vaccine updates

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16
Q

what is antigenic shift

A

one cells is infected with multiple viruses resulting in exchange of viral RNA segments

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17
Q

which is more responsible for pandemics, antigenic drift or shift

A

antigenic shift

18
Q

what is reassortment of genome segments of a virus

A

antigenic shift

19
Q

how is avian influenza virus classified

A

low pathogenic avian influenza or high pathogenic avian influenza

20
Q

where does low pathogenic avian influenza replicate

A

in respiratory and intestinal tracts with few disease symptoms

21
Q

is low pathogenic avian influenza monobasic or multibasic And what is mechanism

A

monobasic- single basic amino acid at cleave site recognized by trypsin like proteases

22
Q

is high pathogenic avian influenza monobasic or multi basic and what is mechanism

A

multibasic- polymerase stuttering and recombination
Multiorgan systemic disease

23
Q

HA of LPAI cleaved by proteases found in ___

24
Q

HA of HPAI is cleaved by proteases found in ___, permitting __

A

many tissues permitting viral replication in liver, lungs, kidneys and brain

25
Q

HPAI produces severe and uniformly ___affecting most organs in birds

A

fatal disease

26
Q

how do you dx avian influenza

A
  1. RT-PCR to detect viral M gene
27
Q

positive avian influenza are tested for presence of ___sequenced to assess if HA cleavage site is LPAI or HPAI

A

H5/H7 genes

28
Q

what is incubation period for swine influenza

A

short incubation period, abrupt disease

29
Q

what are some signs of swine influenza

A

fever, huddling, inactivity, respiratory distress with paroxysmal cough, nasal discharge

30
Q

how do you dx swine influenza

A

nasal swab and PCR

31
Q

what are some signs of equine influenza virus

A

fast onset, reddening of nasal mucosa, discharge, fever, cough, anorexia, depression

32
Q

secondary ___may occur after infection of equine influenza

A

bacterial infections-purulent nasal exudates, bronchopneumonia

33
Q

what HA and NA cause canine influenza virus

A

H3N8, H3N2

34
Q

how does vaccine protect against influenza A virus

A

stimulate production of neutralizing anti-HA antibodies correlate of immune protection

Antibodies binding HA prevent entry into host cells and tag virion for phagocytosis

35
Q

what vaccine is given to birds for influenza A

A

inactivated vaccine

36
Q

what vaccine is given to swine for influenza A

A

whole inactivated virus vaccines

37
Q

what vaccine for influenza A given to horses

A

numerous types- inactivated, adjuvanted viral particles, attenuated and recombinant pox virus vectored

38
Q

what influenza A vaccines are given to dogs

A

bivalent, inactivated vaccines against H3N2 and H3N8

39
Q

where do viral antigens of HPAIV target in cows

A

mammary alveolar epithelial cells

40
Q

what is replication site for HPAIV in cows

A

mammary gland

Microbiology 2 (24 decks)

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