Human group C rotavirus: completion of the genome sequence and gene coding assignments of a non-cultivatable rotavirus

Genome segments 1 and 2 of human group C rotavirus ‘Bristol’ strain were sequenced and their gene–protein coding properties assigned. This work completed the genome sequence of a human group C rotavirus (17,910 bp) and allowed the full gene–protein coding assignment of the 11 segments of dsRNA. Gene 1 is 3309 bp in size and contains a single ORF of 3272 nucleotides, encoding a protein of 1090 amino acids in length with a predicted molecular mass of 125 kDa. Comparison of the translated sequence with cognate published mammalian group A, B and C rotavirus sequences showed 45.2, 26.4 and 92.6% identity, respectively. The sequence contains conserved amino acid motifs including the classic RNA-dependent RNA polymerase motif GDD, indicating that segment 1 encodes the group C rotavirus polymerase protein. Gene 2 is 2736 bp in size and contains a single ORF of 2655 nucleotides encoding a protein of 884 amino acids in length with a calculated molecular mass of 102 kDa. Database searches showed highest homology with VP2, the main structural component of the ‘core’ from group A rotaviruses (46% identity). Alignment of the human group C and A rotavirus VP2 proteins revealed several characteristics common to nucleic acid binding proteins. However, these features were not shared with group B rotavirus VP2.