Which influenza virus subtypes are associated with high pathogenicity in poultry?

Which influenza virus subtypes are associated with high pathogenicity in poultry?

• A. H5N3 and H3N2
• B. H3N5 and H1N7
• C. H5N1 and H7N7
• D. H7N2 and H3N2

Answer: (C)

High pathogenicity in poultry is most strongly linked to certain influenza subtypes, particularly H5 and H7. These subtypes can acquire a polybasic cleavage site in the hemagglutinin protein, which allows the viral HA to be activated by proteases present in many tissues. That change enables systemic infection and severe disease with high mortality in birds. Among the options, H5N1 and H7N7 are classic examples that have caused major highly pathogenic avian influenza outbreaks in poultry. Other subtypes listed are more commonly associated with low-pathogenic avian influenza in poultry, or do not consistently drive the same level of severity. Therefore, the pairing of H5N1 and H7N7 best represents subtypes associated with high pathogenicity in poultry.

High pathogenicity in poultry is most strongly linked to certain influenza subtypes, particularly H5 and H7. These subtypes can acquire a polybasic cleavage site in the hemagglutinin protein, which allows the viral HA to be activated by proteases present in many tissues. That change enables systemic infection and severe disease with high mortality in birds. Among the options, H5N1 and H7N7 are classic examples that have caused major highly pathogenic avian influenza outbreaks in poultry. Other subtypes listed are more commonly associated with low-pathogenic avian influenza in poultry, or do not consistently drive the same level of severity. Therefore, the pairing of H5N1 and H7N7 best represents subtypes associated with high pathogenicity in poultry.