Droplet Digital PCR for Precise Quantification of Human Norovirus in Shellfish Associated with Gastroenteritis Illness

Norovirus is the predominant cause of viral gastroenteritis globally with foodborne outbreaks commonly reported. Filter-feeding bivalve molluscan shellfish can become contaminated with norovirus when grown in waters impacted by inadequately treated effluent wastewater, overflows, or other human feca...

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Main Authors: Daniel Rexin, Laetitia Kaas, Jérémie Langlet, Dawn Croucher, Joanne Hewitt
Format: Article
Language:English
Published: Elsevier 2024-11-01
Series:Journal of Food Protection
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Online Access:http://www.sciencedirect.com/science/article/pii/S0362028X24001479
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author Daniel Rexin
Laetitia Kaas
Jérémie Langlet
Dawn Croucher
Joanne Hewitt
author_facet Daniel Rexin
Laetitia Kaas
Jérémie Langlet
Dawn Croucher
Joanne Hewitt
author_sort Daniel Rexin
collection DOAJ
description Norovirus is the predominant cause of viral gastroenteritis globally with foodborne outbreaks commonly reported. Filter-feeding bivalve molluscan shellfish can become contaminated with norovirus when grown in waters impacted by inadequately treated effluent wastewater, overflows, or other human fecal sources. Contaminated shellfish pose a significant risk to consumers, because combined with a low norovirus infectious dose, oysters and mussels are often eaten raw or lightly cooked resulting in no or minimal virus inactivation, respectively. In addition, shellfish contamination has significant economic impacts on the seafood industry. To improve risk assessments, reverse transcription (RT)-digital droplet PCR (ddPCR) was used to determine the precise norovirus concentrations in 20 shellfish samples, all positive for norovirus genogroup I and/or II (GI or GII) by RT-quantitative PCR (qPCR), and associated with reported norovirus illness in New Zealand. Using RT-ddPCR, total norovirus GI and/or GII concentrations in shellfish ranged between 44 and 4,630 genome copies (GC)/g digestive tissue. Importantly, 40% (8/20) of shellfish samples contained a total norovirus concentration less than 200 GC/g digestive tissue. In parallel, RNase treatment was applied, prior to viral extraction to remove free viral RNA, which subsequently led to average reductions in norovirus GC/g concentration of 37.1% and 19.4% for GI and GII, respectively. These RT-ddPCR data provide valuable evidence for risk assessment of contaminated shellfish and evaluation of safety guidelines and highlight issues associated with setting a safe threshold of norovirus in shellfish.
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spelling doaj-art-cdd108fa5e1e4ccbbd4f1f323d4385662025-08-20T01:47:26ZengElsevierJournal of Food Protection0362-028X2024-11-01871110036310.1016/j.jfp.2024.100363Droplet Digital PCR for Precise Quantification of Human Norovirus in Shellfish Associated with Gastroenteritis IllnessDaniel Rexin0Laetitia Kaas1Jérémie Langlet2Dawn Croucher3Joanne Hewitt4Institute of Environmental Science and Research Limited (ESR), Enteric, Environmental and Food Virology Laboratory, Porirua, New ZealandInstitute of Environmental Science and Research Limited (ESR), Enteric, Environmental and Food Virology Laboratory, Porirua, New ZealandInstitute of Environmental Science and Research Limited (ESR), Enteric, Environmental and Food Virology Laboratory, Porirua, New ZealandInstitute of Environmental Science and Research Limited (ESR), Enteric, Environmental and Food Virology Laboratory, Porirua, New ZealandCorresponding author at: Enteric, Environmental and Food Virology Laboratory, Institute of Environmental Science and Research Limited (ESR), Kenepuru Science Centre, PO BOX 50-348, Porirua 5240, New Zealand.; Institute of Environmental Science and Research Limited (ESR), Enteric, Environmental and Food Virology Laboratory, Porirua, New ZealandNorovirus is the predominant cause of viral gastroenteritis globally with foodborne outbreaks commonly reported. Filter-feeding bivalve molluscan shellfish can become contaminated with norovirus when grown in waters impacted by inadequately treated effluent wastewater, overflows, or other human fecal sources. Contaminated shellfish pose a significant risk to consumers, because combined with a low norovirus infectious dose, oysters and mussels are often eaten raw or lightly cooked resulting in no or minimal virus inactivation, respectively. In addition, shellfish contamination has significant economic impacts on the seafood industry. To improve risk assessments, reverse transcription (RT)-digital droplet PCR (ddPCR) was used to determine the precise norovirus concentrations in 20 shellfish samples, all positive for norovirus genogroup I and/or II (GI or GII) by RT-quantitative PCR (qPCR), and associated with reported norovirus illness in New Zealand. Using RT-ddPCR, total norovirus GI and/or GII concentrations in shellfish ranged between 44 and 4,630 genome copies (GC)/g digestive tissue. Importantly, 40% (8/20) of shellfish samples contained a total norovirus concentration less than 200 GC/g digestive tissue. In parallel, RNase treatment was applied, prior to viral extraction to remove free viral RNA, which subsequently led to average reductions in norovirus GC/g concentration of 37.1% and 19.4% for GI and GII, respectively. These RT-ddPCR data provide valuable evidence for risk assessment of contaminated shellfish and evaluation of safety guidelines and highlight issues associated with setting a safe threshold of norovirus in shellfish.http://www.sciencedirect.com/science/article/pii/S0362028X24001479Food safetyNorovirusOutbreakPublic healthShellfish
spellingShingle Daniel Rexin
Laetitia Kaas
Jérémie Langlet
Dawn Croucher
Joanne Hewitt
Droplet Digital PCR for Precise Quantification of Human Norovirus in Shellfish Associated with Gastroenteritis Illness
Journal of Food Protection
Food safety
Norovirus
Outbreak
Public health
Shellfish
title Droplet Digital PCR for Precise Quantification of Human Norovirus in Shellfish Associated with Gastroenteritis Illness
title_full Droplet Digital PCR for Precise Quantification of Human Norovirus in Shellfish Associated with Gastroenteritis Illness
title_fullStr Droplet Digital PCR for Precise Quantification of Human Norovirus in Shellfish Associated with Gastroenteritis Illness
title_full_unstemmed Droplet Digital PCR for Precise Quantification of Human Norovirus in Shellfish Associated with Gastroenteritis Illness
title_short Droplet Digital PCR for Precise Quantification of Human Norovirus in Shellfish Associated with Gastroenteritis Illness
title_sort droplet digital pcr for precise quantification of human norovirus in shellfish associated with gastroenteritis illness
topic Food safety
Norovirus
Outbreak
Public health
Shellfish
url http://www.sciencedirect.com/science/article/pii/S0362028X24001479
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