Khwansiri NinpanOrnpreya SuptawiwatChompunuch BoonarkartPeerayuht PhuangphungSakda SathirareuangchaiMongkol UiprasertkulPrasert AuewarakulMahidol University. Faculty of Medicine Siriraj Hospital. Department of Microbiology2017-08-072017-08-072017-08-072016Virology Journal. Vol. 13, (2016), 90https://repository.li.mahidol.ac.th/handle/20.500.14594/2678Background: 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-α. Seven isoforms of importin-α have been identified in human. The preference of importin-α3 of avian influenza virus and -α7 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-α1 isoform for their replication. Finding: The mRNA levels of importin-α1, −α3, and –α7 isoforms in human respiratory tract was determined by real-time RT-PCR. The results indicate that mRNA level of importin-α7 was significantly higher than that of importin-α1 (p-value < 0.0001) and importin-α3 (p-value < 0.0001) isoforms in human nasal mucosa while importin-α1 was detected as the highest expression importin-α isoform in lung tissues. Conclusions: These results may explain the preference of importin-α7 isoforms in seasonal influenza viruses in human upper respiratory tract and may suggest a selective pressure toward importin-α7 in human respiratory tract infection of an avian virus.engMahidol UniversityOpen Access articleInfluenza A virusImportin-α1 isoformImportin-α3 isoformImportin-α7 isoformHuman nasal mucosaHuman lung cellsHuman respiratory tractInterspecies barrierArticleBioMed Central10.1186/s12985-016-0546-y