Unexpected detection of porcine rotavirus C strains carrying human origin VP6 gene.

BACKGROUND: Rotavirus C (RVC), a known etiological agent of diarrheal outbreaks, mainly inflicts swine population globally with sporadic incidence in human, cattle, ferret, mink and dog.

OBJECTIVE: To demonstrate the presence of RVC in Indian swine population and characterization of its selected structural (VP6) and non-structural (NSP4 and NSP5) genes.

METHODS: A total of 108 diarrheic samples from different regions of India were used. Isolated RNA was loaded onto polyacrylamide gel to screen for the presence of RVs through the identification of specific electrophoretic genomic migration pattern. To characterize the RVC strains, VP6 gene and NSP4 and NSP5 genes were amplified, sequenced and analyzed.

RESULTS: Based on VP6 gene specific diagnostic RT-PCR, the presence of RVC was confirmed in 12.0% (13/108) piglet fecal specimens. The nucleotide sequence analysis of VP6 gene, encoding inner capsid protein, from selected porcine RVC (PoRVC) strains revealed more than 93% homologies to human RVC strains (HuRVC) of Eurasian origin. These strains were distant from hitherto reported PoRVCs and clustered with HuRVCs, owning I2 genotype. However, the two non-structural genes, i.e. NSP4 and NSP5, of these strains were found to be of swine type, signifying a re-assortment event that has occurred in the Indian swine population.

CONCLUSION: The findings indicate the presence of human-like RVC in Indian pigs and division of RVC clade with I2 genotype into further sub-clades. To the best of our knowledge, this appears to be the first report of RVC in Indian swine population. Incidence of human-like RVC VP6 gene in swine supports its subsequent zoonotic prospective.