Genetic characterization of H5N2 influenza viruses isolated from wild birds in Japan suggests multiple reassortment

Phylogenetic Study of H5 Low Pathogenic Avian Influenza Viruses Detected in Wild Birds in Poland in 2010-2015

Introduction

The genomes of nine H5 subtypes of low pathogenic avian influenza virus (LPAIV) strains identified in wild birds in Poland between 2010 and 2015 were sequenced, and their phylogenetic relationship was determined.

Material and Methods

AIV genome segments were amplified by RT-PCR and the PCR products were sequenced using Sanger method. Phylogenetic trees were generated in MEGA6 software and digital genotyping approach was used to visualise the relationship between analysed strains and other AIVs.

Results

High genetic diversity was found in the analysed strains as multiple subgroups were identified in phylogenetic trees. In the HA tree, Polish strains clustered in two distinct subclades. High diversity was found for PB2, PB1, PA and NP, since 5-8 sublineages could be distinguished. Each strain had a different gene constellation, although relationship of as much as six out of eight gene segments was observed between two isolates. A relationship with poultry isolates was found for at least one segment of each Polish strain.

Conclusion

The genome configuration of tested strains indicates extensive reassortment, although the preference for specific gene constellation could be noticed. A significant relationship with isolates of poultry origin underlines the need for constant monitoring of the AIV gene pool circulating in the natural reservoir.

Genetic characterization of an avian H4N6 influenza virus isolated from the Izumi plain, Japan

An influenza A virus of H4N6 subtype was isolated from the Izumi plain, Japan, in 2013. Genetic analyses revealed that two viral genes (M and NS gene segments) of this isolate were genetically distinct from those of the H4N6 virus isolated from the same place in 2012. Furthermore, three viral genes (PB2, PB1 and M gene segments) of this isolate share high similarity with those of the North American isolates of 2014. These results suggest a high frequency of genetic reassortment of avian influenza viruses in Asian waterfowl and intercontinental movements of avian influenza viruses via migratory waterfowl.