Occurrence and identification of contagious ecthyma in blackbuck.

A carcass of male free ranging adult blackbuck (Antilope cervicapra) was presented for necropsy examination exhibiting thick confluent nodular skin lesions around the mouth and the dry scaly crusts/fissures on the skin of abdomen, thigh and shoulder with subcutaneous haemorrhages. The skin sample around mouth was found positive for orf virus (ORFV) identified by counterimmunoelectrophoresis and PCR. Histopathology of the mouth skin revealed the hyperkeratinization, epidermal sloughing and epithelial hyperplasia showing acanthosis with rete ridges and few eosinophilic intracytoplasmic inclusion bodies in keratinocytes. Further, comparative B2L gene sequence analysis revealed that the virus isolate from blackbuck had shown 97.8-99.6 and 97.6-99.5 % identity at nucleotide and amino acid levels respectively with Indian isolates and maximum identity with ORFV 79/04, an isolate from India. Phylogenetic analysis based on B2L gene also revealed the same evolutionary relationship that it is closely related to Indian isolates. This seems to be the first report of orf in blackbuck from Indian subcontinent.