Molecular epidemiology of swinepox viruses circulating in India

Swinepox is a sporadic virus disease of domestic and wild pigs that mainly occurs during the rainy season. Though the disease is known for a century, research on swinepox especially genetic characterization is scanty. Self-limiting nature of the disease, the non-availability of specific diagnostics as well as the resemblance of clinical signs with other pathogens are some of the issues in the slow progress in swinepox-related research. Recent whole genome sequencing data from the USA, India, and Germany enhanced our understanding of the biology of swinepox virus (SWPV). The objective of the present study is to investigate the molecular epidemiology of two swinepox outbreaks that occurred in 2015 and 2016 one each in Uttar Pradesh, and the Haryana states of India. The appearance of clinical signs in different swine breeds was recorded. The scab samples from infected pigs were collected, DNA extracted, host range genes of SWPV were PCR amplified, sequenced and analyzed for genetic and phylogenetic characterization. Desi (nondescript breed), Yorkshire White pigs, and Landrace cross were found to be infected with SWPV. Host range genes of SWPV analyzed from clinical samples showed very high nucleotide identity with each other. Phylogenetic analyses revealed that SWPVs circulating in India are distinct (Indian lineage) from the SWPV of the USA, Germany, and Russia (European-North American lineage). Our study affirms the existence of two distinct lineages of SWPV globally with differences in clinical lesions between breeds.