Identification of Hsp90 as a species independent H5N1 avian influenza A virus PB2 interacting protein

The avian influenza polymerase protein PB2 subunit is an important mediator of cross species adaptation and adaptation to mammalian cells is strongly but not exclusively associated with an adaptive mutation of the codon at position 627 of the PB2 protein which alters the glutamate normally found at this position to a lysine. This study sought to identify host cell factors in both mammalian and avian cells that interacted in a species specific or species independent manner. Two PB2 fusion proteins differing only in codon 627 were generated and transfected into mammalian and avian cells and interacting proteins identified through co-immunoprecipitation. A number of proteins including Hsp90 were identified and further investigation showed that Hsp90 interacted with both isoforms of PB2 in both mammalian and avian cells. Hsp90 is thus identified as a species independent interacting protein, further confirming that this protein may be a suitable target for anti-influenza drug development.