Bioaccumulation Pattern of the SARS-CoV-2 Spike Proteins in Pacific Oyster Tissues.

There is mounting evidence of the contamination of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the sewage, surface water, and even marine environment. Various studies have confirmed that bivalve mollusks can bioaccumulate SARS-CoV-2 RNA to detectable levels. However, these results do not provide sufficient evidence for the presence of infectious viral particles. To verify whether oysters can bind the viral capsid and bioaccumulate the viral particles, Pacific oysters were artificially contaminated with the recombinant SARS-CoV-2 spike protein S1 subunit (rS1). The bioaccumulation pattern of the rS1 in different tissues was investigated by immunohistological assays. The results revealed that the rS1 was bioaccumulated predominately in the digestive diverticula. The rS1 was also present in the epithelium of the nondigestive tract tissues, including the gills, mantle, and heart. In addition, three potential binding ligands, including angiotensin-converting enzyme 2 (ACE 2)-like substances, A-type histo-blood group antigen (HBGA)-like substances, and oyster heat shock protein 70 (oHSP 70), were confirmed to bind rS1 and were distributed in tissues with various patterns. The colocalization analysis of rS1 and those potential ligands indicated that the distributions of rS1 are highly consistent with those of ACE 2-like substances and oHSP 70. Both ligands are distributed predominantly in the secretory absorptive cells of the digestive diverticula and may serve as the primary ligands to bind rS1. Therefore, oysters are capable of bioaccumulating the SARS-CoV-2 capsid readily by filter-feeding behavior assisted by specific binding ligands, especially in digestive diverticula. IMPORTANCE This is the first article to investigate the SARS-CoV-2 spike protein bioaccumulation pattern and mechanism in Pacific oysters by the histochemical method. Oysters can bioaccumulate SARS-CoV-2 capsid readily by filter-feeding behavior assisted by specific binding ligands. The new possible foodborne transmission route may change the epidemic prevention strategies and reveal some outbreaks that current conventional epidemic transmission routes cannot explain. This original and interdisciplinary paper advances a mechanistic understanding of the bioaccumulation of SARS-CoV-2 in oysters inhabiting contaminated surface water.

Impact of COVID-19 Nonpharmaceutical Interventions on the Extent of Norovirus Contamination in Oyster Production Areas in Ireland during Winter 2020 to 2021.

ABSTRACT: A significant decrease in norovirus prevalence and concentration was observed in oyster production areas in Ireland during winter 2020 to 2021. Oyster production areas impacted by human wastewater discharges that had been undergoing norovirus surveillance since 2018 were investigated. Samples collected in the winter seasons of 2018 to 2019 and 2019 to 2020, prior to when the COVID-19 pandemic interventions were applied, showed a prevalence of 94.3 and 96.6%, respectively, and geometric mean concentrations of 533 and 323 genome copies per g, respectively. These values decreased significantly during the winter of 2020 to 2021 (prevalence of 63.2% and geometric concentration of below the limit of quantification), coinciding with the control measures to mitigate the transmission of severe acute respiratory syndrome coronavirus 2 of the genus Betacoronavirus. Divergence between norovirus GI and GII prevalence and concentrations was observed over the 3-year monitoring period. Norovirus GII was the dominant genogroup detected in winter 2020 to 2021, with over half of samples positive, although concentrations detected were significantly lower than prepandemic winters, with a geometric mean concentration of below the limit of quantification.

Oyster beds in the United Arab Emirates: Important fishing grounds in need of protection.

There is scarce information on the current importance of oyster beds as fishing grounds in the United Arab Emirates (UAE). This study aims to understand the socio-economic value of oyster bed fisheries through questionnaire-based surveys with fishers. Of 106 Emirati fishers interviewed, 67 % use oyster beds due to the proximity to shore, better catch quality, and species abundance. Oyster bed fisheries are recreational and commercial, with handline and fish traps the most common used gears. They provide food for local consumption and cash income. All respondents noticed a fish abundance and size decrease throughout the last decade. Fishers suggest establishing marine protected areas and updating fishing regulations to improve fishing stock status. During the Covid-19 pandemic, oyster fisheries increased, highlighting the value of these fishing grounds for food availability. These fisheries support the local economy and heritage, and urgently need management to ensure the protection of these often-overlooked habitats.