Abstract
Orf virus is a prototype species of the genus Parapoxvirus, subfamily Chordopoxvirinae, family Poxviridae. Japanese orf viruses, infecting sheep and wild Japanese serows (Capricornis crispus), have been considered to be genetically closely related based on the sequence identities of the open reading frames (ORFs) 11, 20, and 132 in their genomes. However, since the genome size of orf viruses is about 140 kbp long, genetic variation among Japanese orf viruses remains unclear. In this study, we analyzed the sequences of ORFs 117, 119, 125, and 127 located in the 3′-proximal region of the viral genome using two strains from sheep and three strains from Japanese serows isolated from 1970 to 2007, and compared them with the corresponding sequences of reference orf viruses from other countries. Sequence analysis revealed that ORFs 125 and 127, which encode the inhibitor of apoptosis and viral interleukin (IL)-10, respectively, were highly conserved among the five Japanese orf viruses. However, high genetic variability with deletions or duplications was observed in ORFs 117 and 119, which encode granulocyte macrophage colony-stimulating factor and IL-2 inhibition factor (GIF), and inducer of cell apoptosis, respectively, in one strain from sheep and two strains from Japanese serows. Our results suggest that genetic variability exists in Japanese orf viruses even in the same host species. This is the first report of genetic variability of orf viruses in Japan.
Highlights
Orf virus is a prototype species of the genus Parapoxvirus, subfamily Chordopoxvirinae, family Poxviridae [1]
We carried out open reading frame (ORF) sequence analysis for five Japanese orf viruses, and our results revealed that the sequences of ORFs 125 and 127 were highly conserved
Observed genetic variability was found to be the 3′-proximal region of Japanese orf viruses
Summary
Orf virus is a prototype species of the genus Parapoxvirus, subfamily Chordopoxvirinae, family Poxviridae [1]. In Japan, the first reports of orf virus infections in sheep and wild Japanese serows (Capricornis crispus) were published in Genetic Variability of Japanese ORFVs. 1952 [4] and 1979 [5], respectively. We have reported nucleotide sequence homology in three open reading frames (ORFs) 11, 20, and 132 among 13 orf viruses isolated or polymerase chain reaction (PCR)-detected from sheep and wild Japanese serows [6]. These ORFs encode viral envelope [7], virus interferon resistance [8], and viral vascular endothelial growth factor (VEGF) [9], respectively. Since only a part of the whole genome (∼140 kbp) has been sequenced so far, the degree of genetic variation in other regions remains unclear
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