Rapid re-emergence and geographic transmission dynamics of a recombinant GII.P16-GII.2 norovirus in the winter of 2016/17
Refereed conference paper presented and published in conference proceedings


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AbstractIntroduction
Norovirus is the key cause of acute gastroenteritis worldwide. In the winter of 2016/17, an uncommon recombinant norovirus GII.P16-GII.2 re-emerged rapidly and circulated at a high level in parts of Asia and Europe, replacing pandemic GII.4 as the predominant circulating genotype. Here, we study the phylodynamics of this re-emerging recombinant norovirus.

Method
We determined complete viral protein 1 (VP1) sequences of GII.P16-GII.2 using Sanger and next-generation sequencing from our ongoing molecular surveillance of norovirus genotype distribution in hospitalized acute gastroenteritis cases in Hong Kong. We analyzed 108 complete/near-complete VP1 sequences (29 from our surveillance and 79 from GenBank) collected from late 2016 to early 2017 using phylogenetic inference and median-joining haplotype network analysis.

Results
In Hong Kong, we observed a sharp increase of GII.P16-GII.2 cases from August 2016 (n=1, 2.7%) and peaking in February 2017 (n=35, 64.8%), outnumbering GII.4 as the predominant genotype. Globally, the earliest strains were all collected from China in August 2016 (including one from Hong Kong), supported phylogenetically by their basal topology on maximum-likelihood tree. These 108 sequences comprised 85 haplotypes, indicating rapid genetic diversification during re-emergence and virus spread. In mainland China, we identified a highly-connected haplotype from which over half of strains and haplotypes were derived. Descendants of this central haplotype had spread to major cities, including Hong Kong, Beijing, and Guangdong as well as intercontinentally to the United States. Although there was evidence of multiple introductions in other countries/regions, subsequent onward dispersal was generally characterized by specific local viral sub-lineages.

Discussion
Recent spread of the re-emerging recombinant GII.P16-GII.2 norovirus may be mediated via a competent haplotype. Diverse viral populations may provide a genetic reservoir for breeding new sub-lineages and establishing geography-specific transmission.

Acknowledgements
This study was supported in part by the Commissioned HMRF (CU-15-C2) and institutional direct grant for research (2016.1.046).
Acceptance Date21/07/2017
All Author(s) ListKirsty Kwok, Nelson Lee, E. Anthony S. Nelson, Ting F. Leung, Raymond W.M. Lai, Paul K.S. Chan, Martin C.W. Chan
Name of ConferenceEpidemics6 - International Conference on Infectious Disease Dynamics
Start Date of Conference29/11/2017
End Date of Conference01/12/2017
Place of ConferenceSitges
Country/Region of ConferenceSpain
Year2017
LanguagesEnglish-United States
Keywordsepidemiology, new variants, norovirus, transmission

Last updated on 2018-16-05 at 17:21