Exam 3: Orthomyxovirus

Question 1

What is majorly responsible for new pandemic influenzas?

Answer 1

The spread of infection in birds increases opportunities for direct infection for humans
If more humans become infected over time, humans act as the mixing vessel for the emergence of a new subtype that can then be easily transmitted between people- such an event would mark the start of an influenza pandemic

Question 2

What is responsible for the emergence of HPAI?

Answer 2

It is usually associated with mutation at the cleavage site in HA molecule
Mutations include point mutations, nucleotide inserts, and recombination
All HPAI’s have been H5 or H7, but few of those are highly pathogenic

Question 3

What is the relative pathogenicity of avian influenza viruses in regard to their hemagglutinin (H) gene and types?

Answer 3

All 16 subtypes of H have been isolated from domestic ducks and have been recognized as sources of generative mammalian flu virus mutants
Only antiboies to H and N (neuraminidase) are associated with resistance to infection

Question 4

Where did the H3Na canine influenza come from?

Answer 4

Started in Florida, blew up from horse tracks and went right into the dogs racing at the greyhound dog tracks

Question 5

In 2015, which subtype of influenza A caused outbreaks in midwestern regions of the US?

Answer 5

H5N2, which led to loss of 50 million birds

Question 6

Describe the genome organization of influenza A viruses

Answer 6

Virions contain 8 segmented, single stranded, negative sense RNA genome
All veterinary isolates, except some swine isolates
Some human isolates

Question 7

Which species serves as a mixing vessel for pandemic avian influenza?

Answer 7

Swine

Question 8

What is a reservoir for influenza A viruses?

Answer 8

Migratory waterfowl, most notably wild ducks, are the natural reservoir of avian influenza. Poultry can also become a reservoir