To assess the quality of shellfish harvest areas, bivalve mollusk samples from three coastal areas of the Campania region in Southwest Italy were evaluated for viruses over a three-year period (2015–2017). Screening of 289 samples from shellfish farms and other locations by qPCR and RT-qPCR identified hepatitis A virus (HAV; 8.9%), norovirus GI (NoVGI; 10.8%) and GII (NoVGII; 39.7%), rotavirus (RV; 9.0%), astrovirus (AsV; 20.8%), sapovirus (SaV; 18.8%), aichivirus-1 (AiV-1; 5.6%), and adenovirus (AdV, 5.6%). Hepatitis E virus (HEV) was never detected. Sequence analysis identified HAV as genotype IA and AdV as type 41. This study demonstrates the presence of different enteric viruses within bivalve mollusks, highlighting the limitations of the current EU classification system for shellfish growing waters.

High pressure processing (HPP) is an increasingly popular non-thermal food processing technology. Study of HPP’s potential to inactivate foodborne viruses has defined general pressure levels required to inactivate hepatitis A virus, norovirus surrogates, and human norovirus itself within foods such as shellfish and produce. The sensitivity of a number of different picornaviruses to HPP is variable. Experiments suggest that HPP inactivates viruses via denaturation of capsid proteins which render the virus incapable of binding to its receptor on the surface of its host cell. Beyond the primary consideration of treatment pressure level, the effects of extending treatment times, temperature of initial pressure application, and matrix composition have been identified as critical parameters for designing HPP inactivation strategies. Research described here can serve as a preliminary guide to whether a current commercial process could be effective against HuNoV or HAV.

The goal of this study was to determine how enteric viruses persist within shellfish tissues. Several lines of novel evidence show that phagocytic blood cells (hemocytes) of Eastern oysters ( Crassostrea virginica ) play an important role in the retention of virus particles. Our results demonstrated an association of virus contamination with hemocytes but not with hemolymph. Live oysters contaminated overnight with hepatitis A virus (HAV) and murine norovirus (MNV) had 56% and 80% of extractable virus associated with hemocytes, respectively. Transfer of HAV-contaminated hemocytes to na�ve (virus-free) oysters resulted in na�ve oyster meat testing HAV positive for up to 3 weeks. Acid tolerance of HAV, MNV, poliovirus (PV), and feline calicivirus (FCV) correlated with the ability of each virus to persist within oysters. Using reverse transcription-PCR (RT-PCR) to evaluate persistence of these viruses in oysters, we showed that HAV persisted the longest (>21 days) and was most acid resistant, MNV and PV were less tolerant of acidic pH, persisting for up to 12 days and 1 day, respectively, and FCV did not persist (<1 day) within oysters and was not acid tolerant. This suggests that the ability of a virus to tolerate the acidic conditions typical of phagolysosomal vesicles within hemocytes plays a role in determining virus persistence in shellfish. Evaluating oyster and hemocyte homogenates and live contaminated oysters as a prelude to developing improved viral RNA extraction methods, we found that viruses were extracted more expediently from hemocytes than from whole shellfish tissues and gave similar RT-PCR detection sensitivities.

Bivalve shellfish readily bioconcentrate pathogenic microbes and substance, such as algal and dinoflagulate toxins, fecal viruses and bacteria, and naturally present vibrio bacteria. High pressure processing (HPP) is currently used as an intervention for Vibrio vulnificus bacteria within molluscan shellfish and its potential to inactivate food-borne viruses and bacteria are discussed. Mechanisms of action of high pressure against bacteria and viruses, as well as how time of pressure application, pressure levels, and pre-pressurization temperature influence inactivation are described. Matrix influences such as ionic strength are noted as important additional considerations. The potential of HPP to influence spoilage and enhance shelf-life of shucked shellfish is also discussed.