Complete nucleotide sequence of a group A avian rotavirus genome and a comparison with its counterparts of mammalian rotaviruses

The nucleotide sequences encoding four structural proteins (VP1–4) and six nonstructural proteins (NSP1–6) of avian rotavirus PO-13 were determined. Based on the results of earlier sequencing studies [Ito et al., 1995, Sequence analysis of cDNA for the VP6 protein of group A avian rota viruses. Arch. Vriol. 140, 605–612; Rohwedder et al., 1997, Chicken rotavirus Ch-1 shows a second type of avian VP6 gene, Virus Genes 15, 65–71; Rohwedder et al., 1997, Bovine rotavirus 993/83 shows a third subtype of avian VP7 protein, Virus Genes 14, 147–151], determination of PO-13 genome sequence has been completed. The PO-13 genome is 18 845 nucleotides in length. It is 290 nucleotides longer than the genome of SA11. The amino acid sequence homology between PO-13 and mammalian rotaviruses ranged from 76–77% (VP1) to 16–18% (NSP1). The features of gene and amino acid sequence were compared with those of the corresponding protein of mammalian rotaviruses. Based on results of the phylogenetic analyses of NSP1, we speculate that an ancestral rotavirus could have separated into groups A, B and C rotaviruses at an early evolutionary stage and that group A rotavirus separated into mammalian and avian rotaviruses with host evolution.