Molecular Characterization and Phylogenetic Analysis of Swinepox Virus of Uttar Pradesh

Swinepox is caused by the Swinepox virus (SPV) of the genus Suipoxvirus, subfamily Chordopoxvirinae in the family Poxviridae. The SPV mostly produces an asymptomatic disease that is characterized by fever, a decrease in feed and water intake, dullness, and scab formation on the skin in the advanced stages. It has a severe economic impact due to reduced production and quality of pork. To prevent it, annual vaccination is recommended. In spite of vaccination, it is endemic in India. Under such circumstances, it is imperative to conduct continuous surveillance of swinepox, its confirmation and characterization for the assessment of any genetic diversity and efficacy of the existing vaccine. Any mutation may lead to the failure of vaccination. With this objective, samples (n=12) were collected from 4 affected districts (n=3 from each) and subjected to PCR-based amplification (524bp) of the swinepox-specific transcription factor-3 (VLTF-3) gene. The PCR products of representative samples (n=4), one each from one district, were outsourced for Sanger sequencing. The analysis of sequences and phylogenetic analysis revealed clustering of all four isolates within a single, well-supported clade with short branch lengths suggestive of a high degree of genetic similarity and possible circulation of closely related viral strains in the studied region. Their relationships are supported by a pairwise nucleotide identity matrix along with the closest genetic affinity aligned with previously reported swinepox virus strains of India and South Korea, forming a regional lineage that reflects limited divergence.