北京市某些医院内腹泻暴发与诺如病毒的相关性研究

Norovirus associated outbreaks of acute gastroenteritis in hospitals in Beijing in late 2006

目的确定2006年11～12月北京市某些医院内发生的住院患者腹泻爆发性流行的病原及其分子生物学特点。方法首先检测腹泻标本中轮状病毒抗原并用聚丙烯酰胺凝胶电泳进行轮状病毒核酸检测，然后用塑转录-聚合酶链反应进行诺如病毒核酸检测，对检测阳性标本进行诺如病毒VP1全基因的扩增；并对其中一例进行全基因克隆、测序和分析。另外对来自不同医院的2份阳性标本中的VP1的5＇端部分序列进行测序分析。结果30份腹泻患者粪便标本中共有17份检测为诺如病毒阳性，总阳性率为56．7％，每一家医院送检标本的阳性率都在42．9％以上。对其中一份标本的诺如病毒VP1全基因序列测定和分析显示为GⅡ-4型诺如病毒。另2份标本中的部分序列测定显示与全基因序列高度保守，只有1个核苷酸的差异，因此也提示为GⅡ-4型诺如病毒。结论诺如病毒是北京地区医院内腹泻暴发的重要病原，此次暴发极可能是由GⅡ-4型诺如病毒引起。

Objective To identify the etiological agent of acute gastroenteritis outbreaks occurred in 6 hospitals in Beijing from November to the end of 2006 and to characterize the virus on molecular biology. Methods Rota-strip was used to detect rotavirus antigen and PAGE for rotavirus RNA in stool specimens collected from patients with gastroenteritis at the first stage. Reverse transcription-polymerase chain reaction（RT-PCR） was performed to detect Norovirus in stool specimens. Full length of Norovirus VP1 genes were amplified from Norovirus positive samples by RT-PCR and sequenced after the gene was cloned into vector pUCm-T. The sequences of partial VP1 gene at the 5＇ end of full-length gene were obtained from 2 of the Norovirus positive samples to analyze the relationship of these viruses at molecular level. Results Norovirus was detected in 17 of the 30 stool specimens with an overall positive rate of 56.7 %. Positive rates were all above 42.9 % in specimens collected from each of the hospital. Sequence analysis on one of the full-length of VP1 amplified by RT-PCR from one of the positive specimens NV8-Beijing indicated that it belonged to GⅡ-4 genotype. This strain shared 94.8 % and 95.2 % identities over the complete major capsid gene to Lanzhou strain form Lanzhou China and Farmington Hill strain from USA which belonged to GⅡ-4 genotype, but only 91.1% identity to the CR2905 from Beijing China identified from specimen collected in late 2004. The sequences of 5＇ end of VP1 genes amplified from other two samples collected from different hospitals showed only one nucleotide mutation compared to NV8-Beijing in the correspondence part, indicating that these two strains also belonged to G Ⅱ-4 genotype. Conclusion Norovirus was the etiological agent causing outbreaks of acute gastroenteritis in hospitals in Beijing and the strain with G Ⅱ-4 genotype which was closer to the Lanzhou and Farmington strains than Beijing strains identified in 2004.