Molecular characterization of a rare G9P[23] porcine rotavirus isolate from China

The fifth most important G genotype, G9 rotavirus, is recognized as an emerging genotype that is spreading around the world. Sequence analysis was completed of a rare group A rotavirus, strain G9P[23], that was designated rotavirus A pig/China/NMTL/2008/G9P[23] and abbreviated as NMTL. It was isolated from a piglet with diarrhea in China. Nucleotide sequence analysis revealed that the VP7 gene clustered within the G9 lineage VId. The VP4 gene clustered within the rare P[23] genotype. NMTL is the first porcine G9 stain reported in China. Thus, to further characterize the evolutionary diversity of the NMTL strain, all gene segments were used to draw a phylogenetic tree. Based on the new classification system of rotaviruses, the NMTL sequence revealed a G9-P[23]-I5-R1-C1-M1-A8-N1-T1-E1-H1 genotype with close similarity to human Wa-like and porcine strains. The results showed that (i) NSP2 and NSP4 genes of NMTL exhibited higher genetic relatedness to human group A rotaviruses than to porcine strains, (ii) the VP2 and VP4 genes clustered with porcine and porcine-like human strains, and (iii) VP1 genes clustered apart from the Wa-like human and porcine clusters. In view of rotavirus evolution, this report provides additional evidence to support the notion that the human and porcine rotavirus genomes might be related.