Phylogenetic analysis of H and N2 genes of avian influenza viruses detected in Ireland between 2003 and 2007

SUMMARYPhylogenetic analysis was performed on the haemagglutinin and neuraminidase subtype N2 genes of low-pathogenic avian influenza viruses (LPAIVs) detected in Ireland between 2003 and 2007. Nucleotide sequences were compared to previously published sequences from the National Centre for Biotechnology Information. Sequences from viruses of the same subtype isolated in different years were compared to examine the possibility that LPAIVs may have been maintained in Ireland from year to year. All viruses had closest identity with published sequences of European lineage, supporting the conclusion that LPAIVs had been introduced to Ireland by dabbling ducks that had migrated from Europe. The data suggested that different subtypes of virus had been introduced each year. However, there was evidence that some LPAIVs may have been maintained in the sedentary waterfowl population for consecutive seasons. Furthermore, almost identical H6 and H10 sequences with different N types were found in isolates from the same season, suggesting that reassortment had occurred.