Phylogeny and genotyping of recent avian low-pathogenic H5 subtype influenza viruses from French ducks

H5 low-pathogenic avian influenza virus (LPAIV) has the potential to become highly pathogenic and to cause serious problems in animal and public health. AIV surveillance and characterization in both wild and domestic species is therefore necessary. In order to acquire molecular information and to identify possible reassortments in French viruses, we analysed the entire genome of five H5N3, three H5N2 and two H5N1 LPAIV, isolated in France between 2002 and 2008 mostly from captive ducks (free-range commercial poultry or decoy ducks). Some of the genome sequences showed atypical characteristics, such as an insertion of 1 aa in the PB1 protein of one H5N3, a highly truncated PB1-F2 protein (11 aa in length instead of 90 aa) in one H5N2, and an insertion of 8 aa in the NS1 protein of H5N1. These two last molecular characteristics have not been described previously. Phylogenetic analysis demonstrated that all genes of French LPAIV, except the closely related matrix protein genes, clustered within the Eurasian avian influenzavirus lineage and fell into at least two phylogenetic subgroups. In addition, the French H5 LPAIV were segregated into eight genotypes, suggesting that many reassortment events have occurred in H5 LPAIV in Europe. However, it is not known whether the reassortment events have occurred in wild waterfowl and/or in captive birds in direct or indirect contact with wild birds.