MOLECULAR CHARACTERIZATION OF AN AVIAN METAPNEUMOVIRUS STRAIN DETECTED IN GUINEA FOWLS (NUMIDA MELEAGRIDIS) EXPERIENCING RESPIRATORY DISEASE

Avian Metapneumovirus (AMPV) of subtype A or B affects mainly turkeys and chickens. However, also pheasants and guinea fowls are susceptible to natural and experimental infection. This study reports, for the first time, the molecular characterization of an AMPV of subtype B detected from guinea fowls during an outbreak of respiratory disease, which occurred in February 2012 in a flock located in a highly populated poultry area of Northern Italy. Nucleotide sequences of F and G protein genes of the strain detected were obtained and aligned against analogous gene sequences of AMPVs subtype B isolated from turkeys or chickens in Italy or deposited/published on GenBank. Phylogenetic analysis was carried out under distance criterion, with neighbour-joining as algorithm, using MEGA5 software. The trees constructed on the alignments of sequence data sets of the F and G protein genes showed one main cluster including all Italian strains isolated after 2001 and this was supported by a high bootstrap value. Inside this cluster, two sub-clusters were observed, one which included strains isolated between 2001 and 2004, and other that included strains isolated after 2007. The strain detected from guinea fowls was included in this last sub-cluster. These findings do not support genetic differences correlated to the host tropism and suggest that circulation of closely related AMPV strains occurs among different avian species in densely populated poultry areas