Analysis and comparison of the 4b core protein gene of avipoxviruses from wild birds: evidence for interspecies spatial phylogenetic variation.

Avipoxviruses have been isolated from a wide variety of avian hosts, and yet little is known regarding the host-virus species variation of the genus Avipoxvirus. We have investigated the variations in the viral 4b core protein gene from six different avipoxviruses based on PCR, Southern blot and nucleotide sequence analysis to evaluate the suitability of this region for differentiation between avipoxvirus isolates. Southern blot and nucleotide sequence analysis revealed considerable interspecies variation between the different virus isolates. In the deduced amino acid sequences (of 142 residues) of the 4b core protein gene, fowlpox virus vaccine strain (FPV-VR250) was found to be similar to the three poxvirus isolates from great tit (GTV-A310, GTV-A311 and GTV-A256), sparrowpox virus (SPV-A468), and pigeonpox virus (PPV-B7) with similarities of 79.6%, 81%, 81%, 64.8% and 84.5%, respectively. Furthermore, comparative phylogenetic analysis of the aligned DNA sequences revealed divergence among the different viruses that can be consistently correlated to the host.