• Microbiology and Biotechnology Letters
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• v.50 no.1
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• pp.126-134
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• 2022

Norovirus (NoV) is an important pathogen causing acute gastroenteritis worldwide. The purpose of the present study was the molecular characterization of NoV. A total of 408 stool specimens collected from hospitalized children associated with acute gastroenteritis in Chiang Rai, Thailand, 2015-2017 were investigated for the presence of NoVs by RT-PCR. NoV GII was detected in 32 samples (7.8%). Five distinct genotypes were identified, including GII.4 (13/32, 40.6%), GII.3 (11/32, 34.3%), GII.17 (4/32, 12.5%), GII.2 (2/32, 6.3%), and GII.14 (2/32, 6.3%). NoV infection occurred mostly in young children under 3 years of age (31/32, 96.9%) and showed the main peak in summer months from March to April (18/32, 56.3%). Phylogenetic analysis revealed that all 13 GII.4 strains clustered with GII.4 Sydney 2012 variant. Representative GII.3 strains were analyzed as a recombinant GII.3P[12] strain. Several amino acid differences were found in the antigenic epitopes and antibody binding sites of the VP1 capsid of the GII.3P[12]. Homology modeling of the P domain of the GII.3P[12] strain demonstrated that 10/13 amino acid differences were predicted to be located on the surface-exposed area of the capsid structure. These amino acid changes might affect the infectivity and the antigenicity of the recombinant GII.3P[12]. The prevalence of GII.4 Sydney 2012 and recombinant GII.3P[12] strains indicates the genetic diversity of circulating NoVs in Thailand, emphazing the importance of continuous surveillance to mornitor newly emerging NoV strains in the future.

• Journal of Microbiology and Biotechnology
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• v.23 no.11
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• pp.1641-1643
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• 2013

Norovirus is the major cause of acute gastroenteritis worldwide. Between November 2012 and June 2013, 1718 stool samples were requested for norovirus antigen testing in the metropolitan areas of South Korea, and 91 samples were genotyped. The norovirus antigen-positive rate peaked at 52.8% in December 2013. A novel norovirus GII.4 variant, GII.4 Sydney 2012, was the most frequently found genotype (60.4%) during this period. This study demonstrates that norovirus activity increased during the winter of 2012-2013 in South Korea and that norovirus GII.4 Sydney 2012 was the cause of the norovirus epidemic during this period.