Posters-Accepted Abstracts: Virol-mycol
Influenza A virus is a substantial threat to human health. During the replication cycle, viruses take advantage of host posttranslational modifications for their own benefit. It was recently reported that influenza A virus proteins interact extensively with the host sumoylation system. Thereby, several viral proteins including NS1 had reported are sumoylated to facilitate viral replication. However, to what extent sumoylation is exploited by influenza A virus and the functional outcomes of viral sumoylation are not well understood. In our study, we found that influenza A virus nucleoprotein (NP)is a target of sumoylation in both NP-transfected cells and virus-infected cells at the two most N-terminal residues, lysine 4 and lysine 7 and that the sumoylation at lysine 7 of NP is highly conserved across different influenzaA subtypes and strains. The NP-sumoylationdefective virus, WSN-NPK4,7R virus, exhibited an early cytoplasmic localization of NP.The growth of the WSN-NPK4,7R virus was highly attenuated compared to that of WSN-WT virus. We evaluated whether members of the PIAS family, the bestcharacterized E3 ligases could function as an E3 ligase for NP. Among all PIAS homologs, over-expression of PIASxa had the strongest effect on NP sumoylation which resulted in an enhanced virus growth suggesting that PIASxa is the predominant E3 ligase for NP. Thus, sumoylation of influenza A virus NP is essential for intracellular trafficking of NP and for virus growth, illustrating sumoylation as a crucial strategy extensively exploited by influenza A virus for survival in the host.