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RUSVM Virology Spring17 > Orthomyxoviridae > Flashcards

Orthomyxoviridae Flashcards

1
Q

Who is the major reservoir of orthomyxoviruses?

A

Aquatic birds

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2
Q

What are the five genera of this family?

A

Influenza A, B, C
Thogotovirus
Isavirus

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3
Q

What is the classification of Influenza viruses based on?

A

Type of hemagglutinin (16 different types)

Type of neurominidase (9 different types)

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4
Q

What information does the full name of an influenza virus tell you?

A

Ex: A/equine/Miami/1/1963(H3N8)

What influenza genra (A, B, C)
Host species
Where it was first discovered
Strain #
Year of discovery
Subtype of hemaglutinin and neurominidase
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5
Q

What is unique about the orthomyxovirus genome?

A

It is segmented

Depending on genus: 6-8 helically symmetrical nucleocapsid segments

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6
Q

What shape are orthomyxoviruses?

A

Pleomorphic: Spherical or filamentous

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7
Q

What are the functions of Hemagglutinin in orthomyxoviruses?

A

Serves as a receptor
Used for membrane fusion
Receptor cleavage

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8
Q

What are the components of orthomyxovirus envelopes?

A

Hemagglutinin (HA)
Neurominidase (NA)
M2 protein

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9
Q

T/F: M1 is a matrix protein that is beneath the lipid envelope layer

A

TRUE

*this is used in diagnostics

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10
Q

What six proteins compose the virus core of orthomyxoviruses?

A 
polymerase basic 1 (PB1)
polymerase basic 2 (PB2)
Polymerase Acid (PA)
Nucleoprotein (NP)
NEP/NS2 (nuclear export protein/non-structural protein)
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11
Q

The genome of orthomyxoviruses are composed of 6-8 segments of linear, _________ sense, _________ stranded RNA

A

Negative sense

Single stranded

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12
Q

Where does orthomxyovirus replication occur?

A

Nucleus

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13
Q

How are orthomxyoviruses transmitted in Aquatic birds? Poultry? Mammals?

A 
Aquatic birds (reservoir): Fecal-oral
Poultry: Ingestion/inhalation
Mammals: Aerosol, droplet, fomites
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14
Q

T/F: Thogotoviruses can be transmitted via ticks.

A

TRUE

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15
Q

Who are the host(s) of Isaviruses?

A

Fish

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16
Q

Why are orthomyxoviruses so difficult to control?

A

They can go through antigenic shift (rearrangement of gene segments) and antigenic drift (point mutations)

17
Q

Who is susceptible to infection of the Equine Influenza Virus?

A

Horses, donkeys, and mules - WORLDWIDE

18
Q

How soon after infection can you see clinical signs in equids with Equine Influenza?

A

Within 24 - 48 hours

*HIGHLY CONTAGIOUS

19
Q

T/F: Equine influenza has a high mortality rate

A

FALSE

high MORBIDITY

20
Q

Where does the equine influenza virus replicate?

A

ciliated respiratory epithelium –> it causes an inflammatory response

21
Q

What are some clinical signs of equine influenza?

A

Nasal discharge, laryngeitis, tracheitis

More severe: HIGH FEVER, anorexia, depression, reddening of nasal mucosa, mucopurulent nasal discharge, Fever can cause abortions

22
Q

T/F: Equine influenza requires aggressive treatment?

A

FALSE: typically self limiting (2-3 weeks)

**May need to treat secondary bacterial infections

23
Q

Equine influenza is highly contagious; how long are horses infectious for?

A

Horses are infectious for up to 5 days post the resolve of clinical signs

24
Q

What animals are at greatest risk for equine influenza?

A

Race horses, breeding stock, show horses

25
Q

What is the test of choice for diagnosing equine influenza?

A

Real time PCR. Must get sample to lab ASAP

**Nasal and pharyngeal swabs

26
Q

T/F: There are effective vaccines available for equine influenza

A

FALSE
There are vaccines available - but they provide no cross protection between various serotypes
*inactivated or live-vectored vax

27
Q

T/F: Swine are considered a mixing vessel for influenza viruses?

What is a mixing vessel?

A

TRUE

Swine can be infected by influenza viruses that infect birds, and influenza viruses that infect humans. Inside the pig these viruses can mutate –> high potential for new zoonotic viruses

28
Q

Where does the swine influenza virus replicate?

A

Upper respiratory epithelium

29
Q

How is the swine influenza transmitted?

A

AEROSOL

30
Q

T/F: Pigs infected with swine influenza can recover

A

True, BUT THEY MUST BE CULLED

31
Q

When should samples be taken to test for swine influenza and from where?

A

Collect samples within24-48 hours of symptom onset.

Deep nasal swabs

32
Q

What dx test should be run to dx swine influenza?

A 
Virus isolation (embryonated chicken eggs are inoculated --> then haemagglutination test)
ELISA, PCR are run for confirmation
33
Q

T/F: There are no therapeutic options available to treat swine influenza

A

TRUE :(

34
Q

T/F: Avian influenza is a reportable pathogen

A

TRUE

35
Q

What are the two subgroups of avian influenza?

A

High pathogenicity avian influenza (mortality 75% or higher)

Low pathogenicity avian influenza (H5 or H7)

36
Q

Where does the avian influenza virus replicate inside the host?

A

GI tract and Respiratory tract

Eventually viremia and spread to other organs

37
Q

In what subgroup of avian influenza viruses would you expect to see infected chickens die without showing clinical signs?

A

High pathogenicity avian influenza: birds can just drop dead without clinical signs

Low pathogenicity avian influenza viruses: chickens will have a decrease in egg production and clinical signs prior to death

38
Q

What diagnostic tests should be performed if you suspect an avian influenza infection?

A
  1. Rt-PCR (look for matrix protein), if positive –> test to see if H5 or H7 –>then sequence to determine the cleavage site

Cleave site will determine high path vs low path strain

High path - basic amino acids at cleavage site
Low path - arginine at cleavage site

39
Q

T/F: there is a vaccine for avian influenza

A

FALSE

focus on: surveillance, biosecurity, and depopulation of infected birds

RUSVM Virology Spring17 (23 decks)

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