Analysis of deletion within the reindeer pseudocowpoxvirus genome

Cases of contagious pustular stomatitis have been reported in Finnish reindeer for many years. Two species of the genus Parapoxvirus of the family Poxviridae have been identified as the causative agent of the disease; orf virus (ORFV) was found during the 1992-1993 epidemic and pseudocowpoxvirus (PCPV) was connected to the 1999-2000 epidemic. The genome of reindeer parapoxvirus from the latter outbreak, isolate F00.120R, was recently sequenced and confirmed as PCPV. The six gene deletion of the right terminus of the F00.120R genome, in comparison to ORFV, was investigated in an attempt to use it in differentiating viruses causing pustular stomatitis in reindeer. The present study describes discovery and analysis of genes 116-121 in reindeer PCPV and in an Italian field isolate of bovine PCPV. The results show that a 5431 bp sequence containing genes 116-121 was likely to have been deleted from the F00.120R genome between the 6th and 7th passage in cell culture, and that these genes are present in other isolates of reindeer and bovine PCPV isolated in Finland during the years 2005-2010. The data presented here extends our knowledge of the PCPV genome, confirming that it contains homologues of all known ORFV genes and further reinforces their close genetic relationship. The similarity between the EEV envelope and GM-CSF inhibitory factor genes from reindeer PCPV and ORFV isolates, Finnish sheep ORFV and cattle PCPV isolates indicate that these viruses have been circulating among Finnish reindeer, cattle and sheep over a long period of time.