Prevalence and Molecular Genotyping of Noroviruses in Market Oysters, Mussels, and Cockles in Bangkok, Thailand

Abstract

Noroviruses are the most common cause of acute gastroenteritis associated with bivalve shellfish consumption. This study aimed to detect and characterize noroviruses in three bivalve shellfish species: oysters (Saccostrea forskali), cockles (Anadara nodifera), and mussels (Perna viridis). The virus concentration procedure (adsorption-twice elution-extraction) and a molecular method were employed to identify noroviruses in shellfish. RT-nested PCR was able to detect known norovirus GII.4 of 8.8 × 10(-2) genome copies/g of digestive tissues from oyster and cockle concentrates, whereas in mussel concentrates, the positive result was seen at 8.8 × 10(2) copies/g of digestive tissues. From August 2011 to July 2012, a total of 300 shellfish samples, including each of 100 samples from oysters, cockles, and mussels were collected and tested for noroviruses. Norovirus RNA was detected in 12.3 % of shellfish samples. Of the noroviruses, 7.7 % were of the genogroup (G) I, 2.6 % GII, and 2.0 % were mixed GI and GII. The detection rate of norovirus GI was 2.1 times higher than GII. With regards to the different shellfish species, 17 % of the oyster samples were positive, while 14.0 and 6.0 % were positive for noroviruses found in mussels and cockles, respectively. Norovirus contamination in the shellfish occurred throughout the year with the highest peak in September. Seventeen norovirus-positive PCR products were characterized upon a partial sequence analysis of the capsid gene. Based on phylogenetic analysis, five different genotypes of norovirus GI (GI.2, GI.3, GI.4, GI.5, and GI.9) and four different genotypes of GII (GII.1, GII.2, GII.3, and GII.4) were identified. These findings indicate the prevalence and distribution of noroviruses in three shellfish species. The high prevalence of noroviruses in oysters contributes to the optimization of monitoring plans to improve the preventive strategies of acute gastroenteritis.

A One-Year Survey of Norovirus in UK Oysters Collected at the Point of Sale

“…Norovirus RNA was detected in 68.7% of samples tested, comparable with the prevalence found in a previous survey carried out using the same methods on oysters from UK production areas (76.2%; Lowther et al 2012b ). The prevalence described here is considerably higher than recorded in surveys of norovirus in bivalve shellfish collected at the point-of-sale in some other countries, for example the United States (3.9%; Woods and Burkhardt 2010), France (9%; Schaeffer et al 2013 ) and Thailand (12.3%: Kittigul et al 2016 ); however, comparatively frequent detection of norovirus has been reported in shellfish from production areas in Ireland (37.1%; Flannery et al 2009 ), Italy (51.5%, Suffredini et al 2014 ) and Spain (52.4%; Polo et al 2015 ). Although the majority of samples were found to be positive, levels exceeding 100 norovirus copies/g were found in only a relatively small percentage of samples (9.7%).…”

Molecular epidemiology and genotype distributions of noroviruses and sapoviruses in Thailand 2000‐2016: A review

“…Genetic characterization of partial NoV capsid gene sequences demonstrated wide variety of NoV genotypes identified in bivalve shellfish. Among these, five different genotypes of NoV GI (GI.2, GI.3, GI.4, GI.5, and GI.9) and four different genotypes of NoV GII (GII.1, GII.2, GII.3, and GII.4) were detected . Most recently, detections of multiple NoV genogroups (GI, GII, and GIV) have been reported in oyster tissues from fresh markets in Bangkok from 2014 to 2016.…”

“…Among these, five different genotypes of NoV GI (GI.2, GI.3, GI.4, GI.5, and GI.9) and four different genotypes of NoV GII (GII.1, GII.2, GII.3, and GII.4) were detected. 57 Most recently, detections of multiple NoV genogroups (GI, GII, and GII, and GIV) were detected, these included 34.1% of GI, 10.5% of GII, 1.2% of mixed GI and GII, and 1.2% of GIV. For NoV GI genotype, only GI.2 was identified, while three GII, GII.4, GII.17, and GII.21 genotypes were identified.…”

In Situ Capture RT-qPCR: A New Simple and Sensitive Method to Detect Human Norovirus in Oysters

“…GI HuNoVs strains have been more frequently encountered in oyster-related outbreaks, and noted to bio-accumulate in various oyster tissues (Le Guyader et al, 2012; Kittigul et al, 2016). GII HuNoVs strains have been also found in oyster tissues, but have been noted to bio-accumulate at very low levels (Wang et al, 2008b; McLeod et al, 2009; Le Guyader et al, 2012).…”