Isolation and phylogenetic analysis of an orf virus from sheep in Makhdoom, India

Orf (contagious ecthyma) is an exanthematic disease caused by a parapoxvirus and occurs primarily in sheep and goats with zoonotic implications. In the present investigation, an orf outbreak in the Muzzaffarnagari sheep flock at the Central Institute for Research on Goats (CIRG), Makhdoom, Mathura, Uttar Pradesh, India, was investigated. Primary goat testes cell culture was used for isolation of the orf virus (ORFV) for the first time. The identity of the virus was confirmed by amplification and sequence analysis of the major envelope glycoprotein (B2L) gene and named ORFV/sheep/India/2012/CIRG. On phylogenetic analysis of B2L protein gene, it clustered with the ORFV strains from China suggesting distinct ORFV strains are circulating in India. On comparison of nucleotide and deduced amino acid sequence analysis (n = 63), a unique 126S residue was observed in ORFV/sheep/India/2012/CIRG. On further sequence analysis (B2L) of different ORFV strains (n = 63), some conserved amino acid residues were identified as host-specific (sheep, human, camel, takin, and musk ox) and have been summarized.