Although the phylogenetic positions of the novel bat virus are slightly divergent in the three trees, they generally show the bat SaV as being most closely related to the SaVs. In our opinion, there is insufficient ground for proposing a new genus for the novel virus under the current framework of taxonomic classification. The ORF1 polyprotein and VP1 capsid protein sequences of the novel bat virus showed obvious phylogenetic clustering with other SaV sequences. It should also be noted that the VP2 protein sequences are shorter and more divergent, and therefore are considered to be less useful in the phylogenetic classification of caliciviruses [4] . Lastly, the genome organization of the bat SaV is highly similar to that of the SaVs as shown above. Hence, together with relatively high sequence identities with other SaVs rather than with calicivirues in other genera (Table S2) , we propose that the novel bat virus be classified as a new member of the genus Sapovirus in the family Caliciviridae. Codon usage and compositional bias analysis