Updates on the genetic variations of Norovirus in sporadic gastroenteritis in Chungnam Korea, 2009-2010

Abstract

Previously, we explored the epidemic pattern and molecular characterization of noroviruses (NoVs) isolated in Chungnam, Korea in 2008, and the present study extended these observations to 2009 and 2010. In Korea, NoVs showed the seasonal prevalence from late fall to spring, and widely detected in preschool children and peoples over 60 years of age. Epidemiological pattern of NoV was similar in 2008 and in 2010, but pattern in 2009 was affected by pandemic influenza A/H1N1 2009 virus. NoV-positive samples were subjected to sequence determination of the capsid gene region, which resolved the isolated NoVs into five GI (2, 6, 7, 9 and 10) and eleven GII genotypes (1, 2, 3, 4, 6, 7, 8, 12, 13, 16 and 17). The most prevalent genotype was GII.4 and occupied 130 out of 211 NoV isolates (61.6%). Comparison of NoV GII.4 of prevalent genotype in these periods with reference strains of the same genotype was conducted to genetic analysis by a phylogenetic tree. The NoV GII.4 strains were segregated into seven distinct genetic groups, which are supported by high bootstrap values and previously reported clusters. All Korean NoV GII.4 strains belonged to either VI cluster or VII cluster. The divergence of nucleotide sequences within VI and VII intra-clusters was > 3.9% and > 3.5%, respectively. The "Chungnam(06-117)/2010" strain which was isolated in June 2010 was a variant that did not belong to cluster VI or VII and showed 5.8-8.2%, 6.2-8.1% nucleotide divergence with cluster VI and VII, respectively.

Rapid Emergence of Novel GII.4 Sub-Lineages Noroviruses Associated with Outbreaks in Huzhou, China, 2008–2012

“…Until 2009, GII.4 2006b variants were still the predominate strains in many countries, including China [ 11 , 31 ]. Since 2010, the newly emerged GII.4 New Orleans 2009 variant seems to have displaced the 2006b sublineage and to have become dominant worldwide [ 32 33 – 34 ].…”

Molecular epidemiology of norovirus in Singapore, 2004-2011

“…GII.4 variants accounted for 83.7% (31/37) of the outbreaks and 75% (42/56) of the sporadic cases investigated. The high prevalence of GII.4 viruses was expected because they have been responsible for five pandemics of gastroenteritis since the late 1990s [Noel et al, ; Siebenga et al, ] and GII.4 is also the predominant genotype in sporadic community cases [Gao et al, ; Park et al, ]. The GII.4 variants predominant in Singapore during the periods 2004–2005, 2006–2009, and 2009–2011 time frames were Hunter 2004, Den Haag 2006b, and New Orleans 2009, respectively.…”

Characterization of norovirus infections in Seoul, Korea

“…The decline in the NoV detection rate we noted in 2009 may be explained by the sudden outbreak of the new influenza during this period. It has been speculated that a drop in prevalence of NoVs since March 2009 to only 1.9% is due to the improved hygienic measures adopted in most countries as a response to the outbreak of H1N1 infections (37, 38).…”