Emergence of an unusual groupA rotavirus VP4 genotype among bovine population in India

Abstract number: O507

Kolpe A.B., Arora R., Yadav M.M., Raut C.G., Chitambar S.D.

Objective: To perform the molecular characterisation and the phylogenetic analysis of unusual G8P[14] bovine group A rotavirus (BoRV-A) strains identified in Pune, western India, during a 2007–2008 rotavirus (RV) epidemiological surveillance.

Methods: Faecal specimens (n = 78) from apparently healthy and diarrheic calves (aged <1 year) were collected per-rectally and investigated for detection of group A rotavirus by antigen capture ELISA (Generic Assay, Germany). ELISA positive specimens (n = 3) were investigated further for molecular characterisation.

Genotyping of BoRV-A strains was carried out on dsRNA extracted from 10% PBS faecal suspensions by a nested and/or heminested RT-PCR specific for VP7 and VP4 genes, using pools of G and P type specific primers. All strains (NIV/BRV/68, NIV/BRV/79, and NIV/BRV/86) were not typeable for the VP4 and VP7 genes.

After purification by "Qiaquick Gel Extraction Kit" (QIAGEN, Germany), the VP4, VP6, VP7, and NSP4 first amplicons of the BoRV-A strains were subjected to sequence analysis with automated sequencer ABI 3130 XL DNA Analyzer (Applied Biosystems, USA). Phylogenetic analysis was performed using MEGA version 4.0.

Results: The NIV/BRV/68, NIV/BRV/79, and NIV/BRV/86 strains exhibited long e-type, G8 and P[14] specificities for VP7 and VP4 genes respectively. By sequence analysis, the VP7 genes displayed high nucleotide (nt) and amino acid (aa) identities to Indian bovine B17 (nt-94.5–98.2% and aa-97.5–99.2%) and Egyptian human EGY2295 (nt-94.2–95.1% and aa-96.8–97.9%) strains, while the VP4 sequences were closely related to the Hungarian human Hun5 strain (nt-94.7–95.4% and aa-97.8–98.2%). The VP6 sequences were found to contain subgroup-I specificity and showed maximum identity with Indian porcine HP140 strain, while NSP4 belonged to genotype-A.

Phylogenetic analysis revealed human and porcine origin of VP4 and VP6 genes respectively, while bovine origin was confirmed by VP7 and NSP4 sequence analysis.

Conclusion: The Indian NIV/BRV/68, NIV/BRV/79, and NIV/BRV/86 strains could be the result of a reassortment between a Hun5-like human strain with P[14] specificity, long e-type and subgroup I, already circulating in Hungary, Italy, and a G8 bovine strain. The genetic relatedness of NIV/BRV strains to Hun5 provides direct evidence for the bovine origin of the VP4 and VP7 genes of human G8P[14] strains.