Orthomyxoviridae

Question 1

Who is the major reservoir of orthomyxoviruses?

Answer 1

Aquatic birds

Question 2

What are the five genera of this family?

Answer 2

Influenza A, B, C
Thogotovirus
Isavirus

Question 3

What is the classification of Influenza viruses based on?

Answer 3

Type of hemagglutinin (16 different types)

Type of neurominidase (9 different types)

Question 4

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

Answer 4

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

Question 5

What is unique about the orthomyxovirus genome?

Answer 5

It is segmented

Depending on genus: 6-8 helically symmetrical nucleocapsid segments

Question 6

What shape are orthomyxoviruses?

Answer 6

Pleomorphic: Spherical or filamentous

Question 7

What are the functions of Hemagglutinin in orthomyxoviruses?

Answer 7

Serves as a receptor
Used for membrane fusion
Receptor cleavage

Question 8

What are the components of orthomyxovirus envelopes?

Answer 8

Hemagglutinin (HA)
Neurominidase (NA)
M2 protein

Question 9

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

Answer 9

TRUE

*this is used in diagnostics

Question 10

What six proteins compose the virus core of orthomyxoviruses?

Answer 10

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

Question 11

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

Answer 11

Negative sense

Single stranded

Question 12

Where does orthomxyovirus replication occur?

Answer 12

Nucleus

Question 13

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

Answer 13

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

Question 14

T/F: Thogotoviruses can be transmitted via ticks.

Answer 14

TRUE

Question 15

Who are the host(s) of Isaviruses?

Answer 15

Fish

Question 16

Why are orthomyxoviruses so difficult to control?

Answer 16

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

Question 17

Who is susceptible to infection of the Equine Influenza Virus?

Answer 17

Horses, donkeys, and mules - WORLDWIDE

Question 18

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

Answer 18

Within 24 - 48 hours

*HIGHLY CONTAGIOUS

Question 19

T/F: Equine influenza has a high mortality rate

Answer 19

FALSE

high MORBIDITY

Question 20

Where does the equine influenza virus replicate?

Answer 20

ciliated respiratory epithelium –> it causes an inflammatory response

Question 21

What are some clinical signs of equine influenza?

Answer 21

Nasal discharge, laryngeitis, tracheitis

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

Question 22

T/F: Equine influenza requires aggressive treatment?

Answer 22

FALSE: typically self limiting (2-3 weeks)

**May need to treat secondary bacterial infections

Question 23

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

Answer 23

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

Question 24

What animals are at greatest risk for equine influenza?

Answer 24

Race horses, breeding stock, show horses

Question 25

What is the test of choice for diagnosing equine influenza?

Answer 25

Real time PCR. Must get sample to lab ASAP | **Nasal and pharyngeal swabs

Question 26

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

Answer 26

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

Question 27

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

Answer 27

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

Question 28

Where does the swine influenza virus replicate?

Answer 28

Upper respiratory epithelium

Question 29

How is the swine influenza transmitted?

Answer 29

AEROSOL

Question 30

T/F: Pigs infected with swine influenza can recover

Answer 30

True, BUT THEY MUST BE CULLED

Question 31

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

Answer 31

Collect samples within24-48 hours of symptom onset. | Deep nasal swabs

Question 32

What dx test should be run to dx swine influenza?

Answer 32

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

Question 33

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

Answer 33

TRUE :(

Question 34

T/F: Avian influenza is a reportable pathogen

Answer 34

TRUE

Question 35

What are the two subgroups of avian influenza?

Answer 35

High pathogenicity avian influenza (mortality 75% or higher) | Low pathogenicity avian influenza (H5 or H7)

Question 36

Where does the avian influenza virus replicate inside the host?

Answer 36

GI tract and Respiratory tract Eventually viremia and spread to other organs

Question 37

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

Answer 37

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

Question 38

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

Answer 38

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

Question 39

T/F: there is a vaccine for avian influenza

Answer 39

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