Isolation and characterization of a parapoxvirus from sheep with papular stomatitis

An outbreak of papular stomatitis occurred in a sheep herd in Hokkaido, Japan. Histological examination, immunohistochemistry, electron microscopic observation, and polymerase chain reaction (PCR) were carried out. Lesions were characterized by epithelial hyperplasia, acanthosis, ballooning degeneration of the spiny layer and stratum granulosum. A parapoxvirus was isolated from the skin lesion of affected sheep and characterized genetically and antigenically. Restriction endonuclease analysis of the PCR product showed an orf virus (ORFV)-specific pattern and the isolate reacted with monoclonal antibodies against ORFV. The partially deduced amino acid sequence of the viral envelope gene was identical to those of the major Japanese ORFVs. These results indicated that the outbreak was due to infection by parapoxvirus. The isolated virus could be classified into ORFV, and was closely related to the major Japanese ORFVs, but not foreign ORFVs or other parapoxviruses.