Characterization of an orf virus isolate from an outbreak in Heilongjiang province, China

Contagious ecthyma, caused by orf virus (ORFV), is an epitheliotrophic contagious disease with zoonotic implications that mainly affects sheep, goats, wild ruminants, and humans. Recently, a novel ORFV strain, OV/HLJ/04, was successfully isolated from the skin and mucosal lesions of a goat with severe clinical sore mouth symptoms in Heilongjiang province of China. The OV/HLJ/04 isolate was characterized by electron microscopy, serological tests, and experimental reproduction of disease. The purified virions exhibited a typical ovoid shape when observed by electron microscopy. Moreover, experimental reproduction of disease showed that a lamb developed typical clinical signs of contagious ecthyma, such as severe vascular proliferation, when inoculated with the virus. Subsequently, amplification of ORFV011 (B2L) gene fragments of viral DNA by polymerase chain reaction (PCR) and gene sequencing were performed. Phylogenetic analysis of the B2L protein gene revealed that this strain clusters with ORFV strains from epidemic-stricken areas worldwide, including recent mainland China isolates. Analysis using ClustalW MegAlign in DNAStar indicated that OV/HLJ/04 (GenBank: KU523790.1) was genetically closely related to the isolates Gansu (JQ904789), with 99.7% identity; NZ2 (DQ184476), with 97.4% identity; and Xinjiang (KF666560), with 90.6% identity. These results may provide insights into the genotype of the etiological agent responsible for the orf outbreak in Heilongjiang Province.