Fengtai District Center for Disease Control and Prevention of Beijing, 3 Xi An St., Feng-Tai District, Beijing, 100071, China.
China CDC, National Institute for Viral Disease Control and Prevention, 100 Ying-Xin St., Xuan-Wu District, Beijing, 100052, China.
J Infect Public Health. 2019 May-Jun;12(3):403-409. doi: 10.1016/j.jiph.2018.12.007. Epub 2019 Jan 15.
Recombinant norovirus strain GII.P7/GII.6 has been circulating in Asia and around the world for at least 20 years, but has been responsible for relatively few outbreaks.
We used statistical analyses, real-time reverse transcription - PCR, and genome sequence analyses to investigate an outbreak of gastroenteritis, identifying the pathogen, the risk factors associated with the outbreak, and the molecular features of GII.P7/GII.6 strains.
An outbreak of gastroenteritis was reported at a school involving 12 students and lasting 6 days, from September 13 to September 18, 2017. Epidemiological studies suggested that norovirus was transmitted from person to person and not via contaminated food or drinking water in this outbreak. Using a sequence analysis of the junction region between open reading frames 1 and 2, the pathogen was identified as a recombinant norovirus (strain GII.P7/GII.6). The full-length genome of the outbreak strain shared 86%-97% identity with those of other GII.P7/GII.6 strains. Phylogenetic trees were constructed from partial open reading frame 1 (ORF1) and ORF2 sequences from the outbreak strain and GII.P7/GII.6 norovirus sequences available in GenBank. On the ORF1 tree, the partial sequences of ORF1 were grouped into cluster A (with GII.6), cluster B (with GII.7), and a separate cluster (C), based on the GII.6 and GII.7 reference strains. The ORF2 tree showed all GII.P7/GII.6 strains formed a cluster together with GII.6 strains. Amino-acid substitutions and insertions/deletions were common in the capsid protein, especially in it's P2 and P1 domains. The outbreak was controlled within several days using appropriate measures.
Because it may play a prominent role in future outbreaks, recombinant norovirus strain GII.P7/GII.6 should be monitored with routine surveillance.
重组诺如病毒 GII.P7/GII.6 株在亚洲乃至全球流行至少 20 年，但导致的暴发相对较少。
我们采用统计学分析、实时 RT-PCR 和基因组序列分析方法，对一起胃肠炎暴发疫情进行调查，明确病原体、与暴发相关的危险因素和 GII.P7/GII.6 株的分子特征。
2017 年 9 月 13 日至 18 日，一所学校发生了一起涉及 12 名学生、持续 6 天的胃肠炎暴发疫情。流行病学研究提示，该起疫情中诺如病毒通过人与人接触传播，而不是通过污染的食物或饮用水传播。采用开放阅读框 1 和 2 之间的连接区序列分析，鉴定病原体为重组诺如病毒（GII.P7/GII.6 株）。暴发株全长基因组与其他 GII.P7/GII.6 株的核苷酸序列同源性为 86%~97%。基于 ORF1 部分序列和 GenBank 中可获得的 GII.P7/GII.6 诺如病毒序列，构建了暴发株和 GII.P7/GII.6 诺如病毒的 ORF1 和 ORF2 系统进化树。在 ORF1 树上，根据 GII.6 和 GII.7 参考株，ORF1 部分序列分为 A 群（GII.6 群）、B 群（GII.7 群）和单独的 C 群。ORF2 树显示所有 GII.P7/GII.6 株与 GII.6 株一起形成一个群。衣壳蛋白，尤其是 P2 和 P1 结构域，存在常见的氨基酸取代和插入/缺失。通过采取适当措施，疫情在几天内得到控制。
由于 GII.P7/GII.6 重组诺如病毒株将来可能在暴发中发挥重要作用，应通过常规监测加以监测。
