[Investigation of a novel VP4 subgenotype of rotavirus in children with diarrhea in Beijing during 2009-2010].

P[8]b is a newly discovered sub-genotype for VP4 gene of group A human rotaviruses (HRV) worldwide. This study was to develop an effective method to identify P[8]a, P[8]b, P[4] and P[6] (sub) genotypes of VP4 genes of HRV and to investigate the prevalence of P[8]b sub-genotype and its G/P combinations of HRV in outpatient and inpatient children with diarrhea in Children's Hospital affiliated to Capital Institute of Pediatrics from 2009 to 2010. By analyzing the collected nucleotide sequences of VP4 gene for all known P genotypes of HRV including P[8]b subtype from GenBank and using softwares of DNAS-tar and MegAlign to align and analyze multiple sequences, probes for P[8]a, P[8]b, P[4] and P[6] (sub) genotypes in the corresponding regions which are highly divergent among genes from different genotypes and conserved within genes of VP4s in same genotypes were designed. Then four sets of primers for PCR amplified DIG labeled probes were designed and corresponding DIG-labeled specific P genotype probes were synthesized with PCR by using VP8* genes of Beijing field HRV strains representing P-genotypes P[8]a, P[8]b, P[4] and P[6], respectively, as templates. Dot-blot hybridization was developed based on cDNA of VP4 genes. The dot-blot hybridization assay for P genotyping was reliable which was confirmed by sequencing of RT-PCR products of VP4 genes amplified from corresponding clinical samples. P genotyping for VP4 genes from 88 HRV positive specimens from the Outpatient Department (55%, 88/160) and 79 HRV positive specimens from the hospitalized (70.5%, 79/112) children with diarrhea indicated that P[8] a subtype was still the most prevalent sub-genotype, which was 96.6% (85/88) and 62.0% (49/79) respectively. The positive rate for P[8]b subtypes in hospitalized children with HRV diarrhea was higher (27.9%, 22/79) than that of in outpatient (2.3%, 2/88) HRV infected children. HRV with P[4] genotype was only found in one of the hospitalized children (1.3%, 1/79), and HRV with P[6] genotype was not detected from specimens either from outpatient or inpatient. G9P[8]b was the predominant combination among the P[8]b subtype of HRV positive specimens in this study. The results in this study indicated that G9P[8]b HRV circulated in children with diarrhea in Beijing.