Phylogenetic studies of H3 low pathogenic avian influenza viruses isolated from wild mallards in Poland

In order to study the variation of low pathogenic avian influenza viruses (AIV) of H3 subtype in the natural reservoir, partial genetic characterisation of four AIV isolates of H3 subtype, recovered from wild mallards in Poland in 2006-2010, was performed. Phylogenetic analysis clearly confirms that there is a constant flow of AIV H3 between wild birds in Eurasia and Africa, and, to a limited degree, to North America (Alaska), with an occasional spill-over to poultry. The analysis of the PA gene of one isolate from 2010 suggests that it is closely related to several HPAI H5N1 viruses belonging to clade 2.3.2 and that, therefore, a reassortment event has occurred recently between low pathogenic and H5N1 highly pathogenic AIV.