Mutations in matrix protein 1 and nucleoprotein caused human-specific defects in nuclear exportation and viral assembly of an avian influenza H7N1 virus.

Nuclear exportation of influenza ribonucleoprotein is a vital step in viral replication cycle. In this study a particular H7N1 (A/ostrich/Zimbabwe/222-E3/1996) virus showed exclusively nuclear localization of the viral nucleoprotein (NP) only in human cell lines but not in cell lines of other species suggesting a human-specific nuclear exportation defect. After 10 passages in human lung cells, an adapted strain (H7N1:P10) could efficiently replicate and export viral NP in human cells.

Evolutionary dynamic of antigenic residues on influenza B hemagglutinin.

Hemagglutinin (HA) of seasonal influenza virus evolves under positive selection pressure exerted by host immunity. It was previously shown that antigenic drift in different influenza B sublineages during different time periods distributed unevenly among different epitopes, and that more recent viruses up to 2007 might have their antigenic drift more focused on certain epitope. We further analyzed whether more recent influenza B viruses up to 2016 followed that same pattern of antigenic evolution.

Expression of importin-α isoforms in human nasal mucosa: implication for adaptation of avian influenza A viruses to human host.

Background: 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.