Test 2: orthomyxo Flashcards by jillian Bastidas

orthomyxoviridea are —

influenza

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

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— line the inner surface of the virion envelope of orthomyxovirus

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

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what kind of genome does orthomyxoviridae have?

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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— on viron envelope of flu virus creat ion channels

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

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what are the two spikes found on flu 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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flu A has how many segments of ssRNA

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

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because fluA is negative sense it brings it own —

polymerase

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

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flu A has — genes that create — proteins

8
10

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

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how to name influenza virus

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

cytoplasm

Influenza A

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

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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RNA replication of flu A occurs in the ___

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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Influenza viruses enter cells via —

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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how does flu A release genome?

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

low

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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.

M2
into

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

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—- are antivirals for flu that attack M2

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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how will fluA initiate mRNA synthesis

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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what is cap snatching

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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HA on flu A is used for

attachment to host cell
fusion to endosome

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NA cleaves — from th cell surface to release infectious viruses

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sialic acid

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

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

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NA inhibitors

— are the reservoir hosts of flu A

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aquatic birds

flu viruses replicates where in the body?

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

antigenic drift vs shift

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

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

antigenic drift

Major changes by --- cause an “epidemic Seasonal Influenza”

drift | drift= small mutations

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

antigenic shift | why we need new vaccines

why are pigs mixing vessels for flu?

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

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

Avian and human both avian 2-3 and human 2-6 receptors

swine influenza causes

respiratory disease, high fever and abortions | H3 N2

swine flu is spread by

inhalation, direct, fomites | H3N2- dogs and pigs and huamns

control of swin flu

vacccine and biosecurity can easier transfer from pigs to humans

2 types of avian flu

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

symptoms of low pathogenic avian flu

ruffled feathers decreased egg production can be asymptomatic

symptoms of highly pathogenic avian influenza

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

the more ---- HA= more virulent virus

cleavable | if many proteases can cut HA then more viruses will form ## Footnote Flu (orthomyxo): enveloped, pleomorphic- spherical or filamentous, medium size (120 nm), large spikes, segmented negative sense ssRNA

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

ubiquitous protease →can effect different organs and systems, leads to systemic infections and death | highly pathogenic avian influenza

LPAI contain a ---- cleavage site on the HA.

monobasic | low pathogeic avian influenza

what types of HA are usually pathogenic?

HA 5 HA 7 | has enhanced cleavability ## Footnote HA found on surface of flu virus

difference between LPAI and HPAI

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

--- is equine flu

H3N8 argentinean, florida and kentucky | can spread to dogs ## Footnote H7N7 no longer exsist

transmission of equine flu ---

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

symptoms of equine flu

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

H3N8

equine flu can spread to dogs cause respiratory tract disease

canine flu symptoms

Respiratory tract disease (coughing, sneezing, nasal discharge, fever), secondary bacterial infections. Often mistaken for kennel cough. supportive care H3N2- birds→dogs | H3N8- equine →dogs

diagnosis of canine flu is by

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

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

neuraminidase (NA)

Describe the structure of influenza A (orthomyxovirus) virus

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

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

H5 H7

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

H3N8 H7N7- extinct

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

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

Test 2: orthomyxo Flashcards

(52 cards)