The emerging GII.P16-GII.4 Sydney 2012 norovirus lineage is circulating worldwide, arose by late-2014 and contains polymerase changes that may increase virus transmission

Noroviruses are a leading cause of human gastroenteritis worldwide. The norovirus genotype GII.4 is the most prevalent genotype in the human population and has caused six pandemics since 1995. A novel norovirus lineage containing the GII.P16 polymerase and pandemic GII.4 Sydney 2012 capsid was recently detected in Asia and Germany. We demonstrate that this lineage is also circulating within the UK and USA and has been circulating since October 2014 or earlier. While the lineage does not contain unique substitutions in the capsid, it does contain polymerase substitutions close to positions known to influence polymerase function and virus transmission. These polymerase substitutions are shared with a GII.P16-GII.2 virus that dominated outbreaks in Germany in Winter 2016. We suggest that the substitutions in the polymerase may have resulted in a more transmissible virus and the combination of this polymerase and the pandemic GII.4 capsid may result in a highly transmissible virus. Further surveillance efforts will be required to determine whether the GII.P16-GII.4 Sydney 2012 lineage increases in frequency over the coming months.

诺如病毒是全球范围内导致人类胃肠炎的首要病原体。诺如病毒基因型GII.4是人类群体中最普遍的基因型，自1995年以来已引发六次全球性大流行。近期在亚洲和德国发现了一种新型诺如病毒谱系，该谱系含有GII.P16聚合酶和大流行株GII.4悉尼2012的衣壳。本研究证实，该谱系在英国和美国也有传播，且传播时间可追溯至2014年10月或更早。尽管该谱系在衣壳中不含有独特的突变，但在影响聚合酶功能和病毒传播的已知位点附近存在聚合酶突变。这些聚合酶突变与2016年冬季在德国流行的高发GII.P16-GII.2病毒所共有的。我们认为，聚合酶中的突变可能导致病毒传播能力的增强，而该聚合酶与流行株GII.4悉尼2012衣壳的结合可能产生高度传染性的病毒。为进一步确定GII.P16-GII.4悉尼2012谱系在未来几个月内是否会增加其频率，需要进一步进行监测工作。