Phylogenetic analysis for HA and NA of SIV isolates retrieved in Farm 1. The strains isolated in our study are highlighted in red. Unrooted bootstrapped neighbour-joining trees of nucleotide sequences of hemagglutinin and neuraminidase. Bootstrap values, calculated on 1000 replicated trees, are shown if ≥ 70 percent. Scale bars indicate substitutions per site. The accession numbers of sequence data are provided in Additional file 2: Table S2.