Episode 15: Influenza

What does H stand for in terms in influenza structure and nomenclature?

Hemagglutinins: important for cellular attachment

What does N stand for in terms in influenza structure and nomenclature?

Neuraminidases: important in determining virulence

True or False: Influenza is an enveloped RNA virus.

True

True or False: Humans are the only known host of influenzas B viruses.

True

Which type of influenza is widespread among many different host species?

Influenza A

Which type of influenza is only known to infect humans, although they’ve been found in some cattle with respiratory signs?

Type C

Which type of influenza is relatively new and identified in normal pigs and cattle? (Identification was based largely on work done at SDSU.)

Type D

How can influenza viruses change over time?

1. Antigenic Drift:

• gradual, continual, small changes in nucleic acid sequences that result in very minor changes overt time.

2. Antigenic Shift:

• rare, abrupt, major change in an influence virus

• two different viral subtypes combine to form a new subtype

What are the common reservoir hosts for influenza viruses?

• wild waterfowl & shorebirds

• people

• pigs

• horses

• dogs

• domestic poultry

• cattle

• cats

What is the difference between LPAI and HPAI strains?

• LPAI: clinical signs are often not seen and very mild and infrequent in population

• HPAI: cause severe problems in affected birds and are very contagious between birds and flock

List animal species that HPAI strains have “spilled into”.

• Diary cattle

• Cats

• Goats

• Alpacas

• Humans

Swine influenza causes primary disease on their own, characterized by:

• acute clinical signs

• high morbidity but low mortality

• paroxysm of cough

• difficult breathing

• anorexia

• lethargy

• rapid resolution over 1-3 days regardless of tx

The reservoir hosts for all influenza A viruses is:

wild waterfowl and shorebirds

True or False: Canine influenza is believed to have originated from an antigenic drift of equine influenza.

True