Identification and characterization of Orf viruses isolated from sheep and goats in Southern Italy

Abstract

Orf virus (ORFV; Family: Poxviridae) is the causative agent of contagious ecthyma, or Orf disease in sheep, goats and other domestic or wild ruminants with a worldwide distribution. The disease is endemic in Italy, but few data are available about its distribution and epidemiology. In the present study we analysed 32 clinical samples, obtained from crusted scab lesions of 5 goats and 27 sheep, from 19 suspected outbreaks of contagious ecthyma in Apulia and Basilicata regions between 2012 and 2014. Negative staining electron microscopy (EM) and polymerase chain reaction (PCR) targeting the late transcription factor gene (VLTF-1) were used to identify the virus. Isolation was also attempted on BHK-21 cell line. PCR was proved to be more sensitive than EM, as it detected the virus in 28 out of 32 samples, whereas the EM detected it only in 26 out of the 32 samples. The majority of isolated strains forms a monophyletic group; these isolates, according to the VLTF-1 sequencing, are high related to ORFV strains previously shown to circulate in Southern Italy.

Keywords: Cell culture propagation; Electron microscopy; ORF virus; PCR; Phylogenetic analysis; VLTF-1 gene.