Orthomyxoviridae Flashcards
Who is the major reservoir of orthomyxoviruses?
Aquatic birds
What are the five genera of this family?
Influenza A, B, C
Thogotovirus
Isavirus
What is the classification of Influenza viruses based on?
Type of hemagglutinin (16 different types)
Type of neurominidase (9 different types)
What information does the full name of an influenza virus tell you?
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
What is unique about the orthomyxovirus genome?
It is segmented
Depending on genus: 6-8 helically symmetrical nucleocapsid segments
What shape are orthomyxoviruses?
Pleomorphic: Spherical or filamentous
What are the functions of Hemagglutinin in orthomyxoviruses?
Serves as a receptor
Used for membrane fusion
Receptor cleavage
What are the components of orthomyxovirus envelopes?
Hemagglutinin (HA)
Neurominidase (NA)
M2 protein
T/F: M1 is a matrix protein that is beneath the lipid envelope layer
TRUE
*this is used in diagnostics
What six proteins compose the virus core of orthomyxoviruses?
polymerase basic 1 (PB1) polymerase basic 2 (PB2) Polymerase Acid (PA) Nucleoprotein (NP) NEP/NS2 (nuclear export protein/non-structural protein)
The genome of orthomyxoviruses are composed of 6-8 segments of linear, _________ sense, _________ stranded RNA
Negative sense
Single stranded
Where does orthomxyovirus replication occur?
Nucleus
How are orthomxyoviruses transmitted in Aquatic birds? Poultry? Mammals?
Aquatic birds (reservoir): Fecal-oral Poultry: Ingestion/inhalation Mammals: Aerosol, droplet, fomites
T/F: Thogotoviruses can be transmitted via ticks.
TRUE
Who are the host(s) of Isaviruses?
Fish
Why are orthomyxoviruses so difficult to control?
They can go through antigenic shift (rearrangement of gene segments) and antigenic drift (point mutations)
Who is susceptible to infection of the Equine Influenza Virus?
Horses, donkeys, and mules - WORLDWIDE
How soon after infection can you see clinical signs in equids with Equine Influenza?
Within 24 - 48 hours
*HIGHLY CONTAGIOUS
T/F: Equine influenza has a high mortality rate
FALSE
high MORBIDITY
Where does the equine influenza virus replicate?
ciliated respiratory epithelium –> it causes an inflammatory response
What are some clinical signs of equine influenza?
Nasal discharge, laryngeitis, tracheitis
More severe: HIGH FEVER, anorexia, depression, reddening of nasal mucosa, mucopurulent nasal discharge, Fever can cause abortions
T/F: Equine influenza requires aggressive treatment?
FALSE: typically self limiting (2-3 weeks)
**May need to treat secondary bacterial infections
Equine influenza is highly contagious; how long are horses infectious for?
Horses are infectious for up to 5 days post the resolve of clinical signs
What animals are at greatest risk for equine influenza?
Race horses, breeding stock, show horses
What is the test of choice for diagnosing equine influenza?
Real time PCR. Must get sample to lab ASAP
**Nasal and pharyngeal swabs
T/F: There are effective vaccines available for equine influenza
FALSE
There are vaccines available - but they provide no cross protection between various serotypes
*inactivated or live-vectored vax
T/F: Swine are considered a mixing vessel for influenza viruses?
What is a mixing vessel?
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
Where does the swine influenza virus replicate?
Upper respiratory epithelium
How is the swine influenza transmitted?
AEROSOL
T/F: Pigs infected with swine influenza can recover
True, BUT THEY MUST BE CULLED
When should samples be taken to test for swine influenza and from where?
Collect samples within24-48 hours of symptom onset.
Deep nasal swabs
What dx test should be run to dx swine influenza?
Virus isolation (embryonated chicken eggs are inoculated --> then haemagglutination test) ELISA, PCR are run for confirmation
T/F: There are no therapeutic options available to treat swine influenza
TRUE :(
T/F: Avian influenza is a reportable pathogen
TRUE
What are the two subgroups of avian influenza?
High pathogenicity avian influenza (mortality 75% or higher)
Low pathogenicity avian influenza (H5 or H7)
Where does the avian influenza virus replicate inside the host?
GI tract and Respiratory tract
Eventually viremia and spread to other organs
In what subgroup of avian influenza viruses would you expect to see infected chickens die without showing clinical signs?
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
What diagnostic tests should be performed if you suspect an avian influenza infection?
- 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
T/F: there is a vaccine for avian influenza
FALSE
focus on: surveillance, biosecurity, and depopulation of infected birds
