Human norovirus GII.4 Hong Kong variant shares common ancestry with GII.4 Osaka and emerged in Thailand in 2016

Abstract

Human norovirus is a leading cause of non-bacterial acute gastroenteritis, which affects all age groups and are found globally. Infections are highly contagious and often occur as outbreaks. Periodic emergence of new strains are not uncommon and novel variants are named after the place of first reported nucleotide sequence. Here, we identified human norovirus GII.4 Hong Kong variant in stool samples from Thai patients presented with acute gastroenteritis. Comparison of amino acid residues deduced from the viral nucleotide sequence with those of historical and contemporary norovirus GII.4 strains revealed notable differences, which mapped to the defined antigenic sites of the viral major capsid protein. Time-scaled phylogenetic analysis suggests that GII.4 Hong Kong shared common ancestry with GII.4 Osaka first reported in 2007, and more importantly, did not evolve from the now-prevalent GII.4 Sydney lineage. As circulation of norovirus minor variants can lead to eventual widespread transmission in susceptible population, this study underscores the potential emergence of the GII.4 Hong Kong variant, which warrants vigilant molecular epidemiological surveillance.

Antigenic Site Immunodominance Redirection Following Repeat Variant Exposure

“…Conversely, exchange of site G resulted in a high correlation with all the variants tested, except GII.4 2006 Den Haag, which was slightly lower (r = 0.67, p = 0.001). Notably, GII.4 2019 Hong Kong, a divergent variant that has only recently been detected and is not yet widely circulating in adults [49,50], also highly correlated with other GII.4 variants, with the best correlation to GII.…”

“…Conversely, exchange of site G resulted in a high correlation with all the variants tested, except GII.4 2006 Den Haag, which was slightly lower (r = 0.67, p = 0.001). Notably, GII.4 2019 Hong Kong, a divergent variant that has only recently been detected and is not yet widely circulating in adults [49,50], also highly correlated with other GII.4 variants, with the best correlation to To determine if the redirection of nAb from site A to both sites A and G corresponded with the breadth of GII.4 nAb measured in the 2019 adult sera, we compared the titer of each antigenic site with the titer to each GII.4 variant. As expected for variants, each GII.4 significantly correlated with the others, with two groups of high correlation (r ≥ 0.7, p ≤ 0.005) (Figure 6): ancestral variants (1987 Camberwell, 1997 Grimsby, and 2002 Farmington Hills) and contemporary variants (2006 Den Haag, 2009 New Orleans, and 2012 Sydney) [43,48].…”

Antigenic Characterization of Novel Human Norovirus GII.4 Variants San Francisco 2017 and Hong Kong 2019

“…Since 2012, the Sydney 2012 variant has predominated worldwide ( 6 ). In 2019, GII.4 noroviruses that did not cluster with any known variants were reported circulating in different countries as early as 2016 ( 7 , 8 ). Based on phylogenetic clustering and number of mutations on major capsid viral proteins (VP1), the variant was classified GII.4 Hong Kong 2019 ( 7 ).…”