Which influenza strains can be highly pathogenic?

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Multiple Choice

Which influenza strains can be highly pathogenic?

The main idea is that certain avian influenza subtypes have the potential to become highly pathogenic in birds. In particular, the H5 and H7 subtypes are the ones most commonly associated with highly pathogenic avian influenza (HPAI). The reason is structural: when the hemagglutinin (HA) protein of these viruses acquires a polybasic cleavage site, it can be activated by proteases found in many tissues, allowing the virus to replicate systemically rather than staying confined to the respiratory or gastrointestinal tracts. This systemic replication leads to severe disease and high mortality in poultry, which is the hallmark of high pathogenicity. In contrast, other subtypes like H1N1 and H3N2 are typically seasonal human influenza strains with low pathogenicity in birds, and H9/H10 are generally considered low pathogenic avian influenza. So, among the options, H5 and H7 are the subtypes known for the potential to be highly pathogenic.

The main idea is that certain avian influenza subtypes have the potential to become highly pathogenic in birds. In particular, the H5 and H7 subtypes are the ones most commonly associated with highly pathogenic avian influenza (HPAI). The reason is structural: when the hemagglutinin (HA) protein of these viruses acquires a polybasic cleavage site, it can be activated by proteases found in many tissues, allowing the virus to replicate systemically rather than staying confined to the respiratory or gastrointestinal tracts. This systemic replication leads to severe disease and high mortality in poultry, which is the hallmark of high pathogenicity.

In contrast, other subtypes like H1N1 and H3N2 are typically seasonal human influenza strains with low pathogenicity in birds, and H9/H10 are generally considered low pathogenic avian influenza. So, among the options, H5 and H7 are the subtypes known for the potential to be highly pathogenic.

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