Understanding the phylogenetics of APVs is essential to the understanding of host specificity and virulence, but also to provide insights into the variation of different viruses. Although the complete genome sequences of FWPV and CNPV are available [7, 8] , little is known about APV phylogeny. This is probably because of the difficulty in identifying pan-genus or species-specific PCR primers that can be used to amplify different genes. The most common PCR locus used until now has been the P4b locus [21] . Recent phylogenetic studies of APV isolates based on this locus [22, 23] indicated that most isolates clustered around either CNPV or FWPV, while another study based on the same locus demonstrated a third cluster, from psittacine birds [66] . Amano and coworkers [38] showed that the CNPV thymidine kinase locus was highly diverged from that of FWPV. The extent of this divergence was further illustrated by the fact that the amino acid similarity between CNPV and FWPV orthologue P4b was only 64.2% [23, 38] . A recent study, based on three different genes including the P4b, revealed that penguinpox virus, isolated from lesions around the eyes of African penguins (Spheniscus demersus), was most closely related to turkeypox virus, ostrichpox virus and pigeonpox virus [67] .