Randomized, Double-Blinded Clinical Trial for Human Norovirus Inactivation in Oysters by High Hydrostatic Pressure Processing

Abstract

Contamination of oysters with human noroviruses (HuNoV) constitutes a human health risk and may lead to severe economic losses in the shellfish industry. There is a need to identify a technology that can inactivate HuNoV in oysters. In this study, we conducted a randomized, double-blinded clinical trial to assess the effect of high hydrostatic pressure processing (HPP) on Norwalk virus (HuNoV genogroup I.1) inactivation in virus-seeded oysters ingested by subjects. Forty-four healthy, positive-secretor adults were divided into three study phases. Subjects in each phase were randomized into control and intervention groups. Subjects received Norwalk virus (8FIIb, 1.0 ؋ 10 4 genomic equivalent copies) in artificially seeded oysters with or without HPP treatment (400 MPa at 25°C, 600 MPa at 6°C, or 400 MPa at 6°C for 5 min). HPP at 600 MPa, but not 400 MPa (at 6°or 25°C), completely inactivated HuNoV in seeded oysters and resulted in no HuNoV infection among these subjects, as determined by reverse transcription-PCR detection of HuNoV RNA in subjects' stool or vomitus samples. Interestingly, a white blood cell (granulocyte) shift was identified in 92% of the infected subjects and was significantly associated with infection (P ‫؍‬ 0.0014). In summary, these data suggest that HPP is effective at inactivating HuNoV in contaminated whole oysters and suggest a potential intervention to inactivate infectious HuNoV in oysters for the commercial shellfish industry.

Inactivation of Human Norovirus in Contaminated Oysters and Clams by High Hydrostatic Pressure

“…GI.1 8FIIb NoV in a stool sample from patient 34-9 of a human volunteer study (18) and a GII.4 strain (Cincinnati Children's Hospital) in fecal suspension were used in this study. The stool was suspended in sterile deionized water, followed by centrifugation at 4,000 ϫ g for 20 min.…”

“…Arcangeli et al (17) reported that HHP at 500 MPa for 1 min was effective in inactivating MNV-1, with Ͼ4 log 10 reductions of the virus in experimentally contaminated live clams. In a recent clinical trial, no NoV infection was observed when NoV-inoculated oyster meats, inoculated through injection, were treated at 600 MPa at 6°C for 5 min and subsequently fed to human subjects (18).…”

“…The objectives of this study were to (i) determine whether the PGM-MB binding assay could be used to quantify infectious NoV by comparing the results obtained using the binding assay with those reported in the human challenge study (18); (ii) determine whether NoV in two important genogroups, GI and GII, had different pressure sensitivities; and (iii) identify effective HHP parameters for processing of oysters and clams.…”

Norovirus in symptomatic and asymptomatic individuals: cytokines and viral shedding

“…The study population was comprised of individuals from two separate NoV challenge studies, described in [14,15]. Overall serum cytokine responses for this population are reported in [12].…”

Immunocompetent Adults from Human Norovirus Challenge Studies Do Not Exhibit Norovirus Viremia

“…To determine whether immunocompetent adults develop NoV viremia, we tested samples from NoV-infected adults who participated in two challenge studies, which are described fully elsewhere (8,9). On the basis of our power calculations, we chose 38 serum samples from 20 subjects (13 Norwalk virus [NV]-infected subjects and 7 Snow Mountain virus [SMV]-infected subjects).…”