Lecture 16: Orthomyxoviruses

Question 1

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

Answer 1

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

Question 2

what is reservoir host for orthomyxoviridae/ influenza viruses

Answer 2

aquatic birds

Question 3

what type of genome structure does influenza A have

Answer 3

segmented - sense ssRNA

Question 4

influenza A viruses are subtypes based on ___

Answer 4

hemagglutinin and neuroamindase surface glycoproteins

Question 5

what Baltimore classification are influenza A viruses

Answer 5

group V

Question 6

What is pathogenesis for influenza A virus replication

Answer 6

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

Question 7

what is HA necessary for in influenza A virus

Answer 7

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

Question 8

what is key virulence factor of Influenza A

Answer 8

cleavage site

Question 9

what is monobasic influenza virus cleaved by and what tissues affect

Answer 9

cleaved by trypsin like proteases and only goes to limited tissues

Question 10

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

Answer 10

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

Question 11

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

Answer 11

16, 9

Question 12

how do migrating water fowl spread influenza

Answer 12

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

Question 13

what is antigenic drift

Answer 13

minor changes in HA or NA, seasonal changes

Question 14

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

Answer 14

random point mutation, antigenic drift

Question 15

how does antigenic drift affect vaccines

Answer 15

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

Question 16

what is antigenic shift

Answer 16

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

Question 17

which is more responsible for pandemics, antigenic drift or shift

Answer 17

antigenic shift

Question 18

what is reassortment of genome segments of a virus

Answer 18

antigenic shift

Question 19

how is avian influenza virus classified

Answer 19

low pathogenic avian influenza or high pathogenic avian influenza

Question 20

where does low pathogenic avian influenza replicate

Answer 20

in respiratory and intestinal tracts with few disease symptoms

Question 21

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

Answer 21

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

Question 22

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

Answer 22

multibasic- polymerase stuttering and recombination
Multiorgan systemic disease

Question 23

HA of LPAI cleaved by proteases found in ___

Answer 23

intestine

Question 24

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

Answer 24

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

Question 25

HPAI produces severe and uniformly ___affecting most organs in birds

Answer 25

fatal disease

Question 26

how do you dx avian influenza

Answer 26

1. RT-PCR to detect viral M gene

Question 27

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

Answer 27

H5/H7 genes

Question 28

what is incubation period for swine influenza

Answer 28

short incubation period, abrupt disease

Question 29

what are some signs of swine influenza

Answer 29

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

Question 30

how do you dx swine influenza

Answer 30

nasal swab and PCR

Question 31

what are some signs of equine influenza virus

Answer 31

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

Question 32

secondary ___may occur after infection of equine influenza

Answer 32

bacterial infections-purulent nasal exudates, bronchopneumonia

Question 33

what HA and NA cause canine influenza virus

Answer 33

H3N8, H3N2

Question 34

how does vaccine protect against influenza A virus

Answer 34

stimulate production of neutralizing anti-HA antibodies correlate of immune protection Antibodies binding HA prevent entry into host cells and tag virion for phagocytosis

Question 35

what vaccine is given to birds for influenza A

Answer 35

inactivated vaccine

Question 36

what vaccine is given to swine for influenza A

Answer 36

whole inactivated virus vaccines

Question 37

what vaccine for influenza A given to horses

Answer 37

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

Question 38

what influenza A vaccines are given to dogs

Answer 38

bivalent, inactivated vaccines against H3N2 and H3N8

Question 39

where do viral antigens of HPAIV target in cows

Answer 39

mammary alveolar epithelial cells

Question 40

what is replication site for HPAIV in cows

Answer 40

mammary gland