Microorganisms (Dec 2022)

Study on the Effect of Relaying on Norovirus Reduction from <i>Crassostrea gigas</i> Oysters

  • Roberta Battistini,
  • Chiara Masotti,
  • Cristiana Maurella,
  • Erica Costa,
  • Mino Orlandi,
  • Mirvana Feletti,
  • Carlo Ercolini,
  • Laura Serracca

DOI
https://doi.org/10.3390/microorganisms10122389
Journal volume & issue
Vol. 10, no. 12
p. 2389

Abstract

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Norovirus (NoV) is the most important cause of seafood-borne gastroenteritis worldwide, mainly associated with the consumption of raw oysters. NoV is often present in oysters that comply with existing control standards for shellfish. Therefore, the improvement of post-harvest treatments and practices can represent one of the main strategies to reduce the incidence of viral diseases related to shellfish. This study aimed to investigate long-term relays for the reduction of NoV levels in live oysters, during the high-risk cold months, by transferring the oysters from a more contaminated site to two sites with lower NoV levels. The efficacy of relaying was evaluated by analyzing oyster samples collected at days 0 (T0) and 30 (T30) for NoV levels using a real-time quantitative PCR (RT-qPCR). The NoV level at the relay sites was consistently lower than at the harvest site. The relay process for 30 days in seawater with a lower NoV level resulted in a decrease in the NoV load compared to day 0 with significant reductions depending on the site and genogroup of NoV considered. These results suggest that long-term relaying of oysters to reduce NoV levels is promising and could help growers to improve oyster safety; however, further investigations are needed.

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