Detection and Molecular Characterization of Picobirnaviruses (PBVs) in the Mongoose: Identification of a Novel PBV Using an Alternative Genetic Code

We report high rates of detection (35.36%, 29/82) of genogroup-I (GI) picobirnaviruses (PBVs) in non-diarrheic fecal samples from the small Indian mongoose (Urva auropunctata). In addition, we identified a novel PBV-like RNA-dependent RNA polymerase (RdRp) gene sequence that uses an alternative mitochondrial genetic code (that of mold or invertebrate) for translation. The complete/nearly complete gene segment-2/RdRp gene sequences of seven mongoose PBV GI strains and the novel PBV-like strain were obtained by combining a modified non-specific primer-based amplification method with conventional RT-PCRs, facilitated by the inclusion of a new primer targeting the 3&prime
untranslated region (UTR) of PBV gene segment-2. The mongoose PBV and PBV-like strains retained the various features that are conserved in gene segment-2/RdRps of other PBVs. However, high genetic diversity was observed among the mongoose PBVs within and between host species. This is the first report on detection of PBVs in the mongoose. Molecular characterization of the PBV and PBV-like strains from a new animal species provided important insights into the various features and complex diversity of PBV gene segment-2/putative RdRps. The presence of the prokaryotic ribosomal binding site in the mongoose PBV genomes, and analysis of the novel PBV-like RdRp gene sequence that uses an alternative mitochondrial genetic code (especially that of mold) for translation corroborated recent speculations that PBVs may actually infect prokaryotic or fungal host cells.