Expression of importin-[alpha] isoforms in human nasal mucosa: implication for adaptation of avian influenza A viruses to human host

Transportation into the host cell nucleus is crucial for replication and transcription of influenza virus. The classical nuclear import is regulated by specific cellular factor, importin-[alpha]. Seven isoforms of importin-[alpha] have been identified in human. The preference of importin-[alpha]3 of avian influenza virus and -[alpha]7 isoform of human strains during replication in human cells was previously identified. In addition, both avian and human influenza viruses were shown to use importin-[alpha]1 isoform for their replication. These results may explain the preference of importin-[alpha]7 isoforms in seasonal influenza viruses in human upper respiratory tract and may suggest a selective pressure toward importin-[alpha]7 in human respiratory tract infection of an avian virus.