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Open Access Highly Accessed Research article

Isolation and phylogenetic analysis of orf virus from the sheep herd outbreak in northeast China

Wei Li1, Zhangyong Ning24*, Wenbo Hao1, Deguang Song3, Feng Gao3, Kui Zhao3, Xiaoqing Liao1, Ming Li1, Daniel L Rock4 and Shuhong Luo12*

Author Affiliations

1 Institute of Antibody Engineering, School of Biotechnology, Southern Medical University, N. Guangzhou Avenue, 1838, Guangzhou, 510515, People’s Republic of China

2 College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, People’s Republic of China

3 College of Animal Science and Veterinary Medicine, Jilin University, Changchun, 130062, China

4 Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Champaign-Urbana, S. Lincoln Avenue, 2001, Urbana, IL 61802, USA

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BMC Veterinary Research 2012, 8:229  doi:10.1186/1746-6148-8-229

Published: 23 November 2012

Abstract

Background

Orf is a zoonotic and epitheliotrophic contagious disease that mainly affects sheep, goats, wild ruminants, and humans with a worldwide distribution. To date, there is little information on the characterization of ORFV strains that are endemic in Mainland China. In addition, the relationship between the severity of disease and the molecular profile of ORFV strains has not been fully elucidated.

Results

From the recent outbreak of a sheep herd in Nongan, northeast of China, the novel orf virus (ORFV) strain NA1/11 was successfully isolated. Western blot analysis indicated that the NA1/11 strain cross reacts with monoclonal antibody A3 and infected sheep ORFV antiserum. The purified virions revealed the typical ovoid shape when observed by atomic force microscopy. To determine the genetic characteristics of the NA1/11 strain, the sequences of ORFV011 (B2L), ORFV059 (F1L), ORFV109, ORFV110 and ORFv132 (VEGF) genes were amplified and compared with reference parapoxvirus strains. Non-metric multidimensional scaling (nMDS) was performed to analyze the nucleotide similarities between different ORFV strains.

Conclusions

Phylogenetic analysis based on ORFV 011 nucleotide sequences showed that the NA1/11strain was closely related to Xinjiang and Gansu strains. ORFV110 and ORFV132 genes are highly variable. The results revealed that precise phylogenetic analysis might provide evidence for genetic variation and movement of circulating ORFV strains in Northeast China. In addition, nMDS analysis showed that geographic isolation and animal host are likely major factors resulting in genetic differences between ORFV strains.

Keywords:
Parapoxvirus; Orf virus; Phylogenetic analysis; Sheep; Zoonosis; nMDS