Variable High-Pressure-Processing Sensitivities for Genogroup II Human Noroviruses

Sample Processing and Concentration Methods for Viruses from Foods and the Environment Prior to Detection

Viruses are the leading cause of foodborne illness globally. Concentration of viruses from samples is important for detection because viral contamination of foods often occurs at low levels. In general, virus concentration methods can be classified as either nonspecific, exploiting the relatively homogeneous physicochemical properties of the virus to separate/concentrate it from the sample matrix, or specific, relying on recognition elements such as antibodies to specifically capture and separate viruses from foods. Numerous nonspecific and specific techniques for virus concentration have been reported, each with its own advantages and limitations. Factors to consider can include reagent and equipment costs, time-to-result, ease of use, and potential to eliminate matrix-associated inhibitors. The purpose of this review is to survey the different foodborne virus concentration techniques and their efficacy in various food and environmental matrices as well as discuss some emerging techniques for purification and concentration of viral pathogens from food samples.

High-Pressure Processing of Different Tissue Homogenates from Pigs Challenged with the African Swine Fever Virus

African swine fever (ASF) is a disease that is a growing threat to the global swine industry. Regulations and restrictions are placed on swine movement to limit the spread of the virus. However, these are costly and time-consuming. Therefore, this study aimed to determine if high-pressure processing (HPP) sanitization techniques would be effective against the ASF virus. Here, it was hypothesized that HPP could inactivate or reduce ASF virus infectivity in tissue homogenates. To test this hypothesis, 30 aliquots of each homogenate (spleen, kidney, loin) were challenge-infected with the Turin/83 strain of ASF, at a 10 7.20 median hemadsorption dose (HAD)50/mL. Subsequently, eight aliquots of each homogenate were treated with 600 millipascal (600 MPa) HPP for 3, 5, and 7 min. Six untreated aliquots were used as the controls. Virological results showed a reduction in the viral titer of more than 7-log. These results support the validity of the study hypothesis since HPP treatment was effective in inactivating ASFV in artificially prepared samples. Overall, this study suggests the need for further investigation of other ASFV-contaminated meat products.

Ultralow temperature high pressure processing enhances inactivation of norovirus surrogates

High pressure processing (HPP) is a powerful non-thermal method for inactivating pathogens. Human norovirus and genetically-related caliciviruses are moderately sensitive to temperatures above 0 °C with >400 MPa (MPa) or higher required to inactivate multiple logs of virus. Sensitivity of murine norovirus (MNV) and Tulane virus (TV) to ice phase transitions was evaluated using ultra low temperature HPP. Identical samples containing MNV or TV were either equilibrated to +1.5 °C (thawed) or -40 °C (frozen) 24 h prior to pressurization. All samples (thawed and frozen) were then placed in a pre-chilled chamber which was then rapidly filled with -40 °C chamber fluid. Samples were immediately pressurized for 5 min at 200, 250 or 300 MPa. Controls were not pressurized. For samples that were thawed and then pressurized in 40 °C chamber fluid, the MNV average log reduction at 200 MPa was 4.4, while >6.1 log reduction (non-detectable) was achieved at 250 and 300 MPa. TV samples averaged 2.3, 5 and 4.3 log reduction at 200, 250, and 300 MPa respectively. For samples that were frozen and then pressurized in 40 °C chamber fluid, the MNV average log reductions were 2.3, 3.2 and 4.2 at 200 MPa, 250 MPa and 300 MPa, respectively, while TV samples averaged 0.81, 2.3 and 1.7 log reductions at 200, 250, and 300 MPa, respectively. Inactivation of TV within oysters at these pressures was also demonstrated. Overall, results indicate that in addition to enhancing inactivation of norovirus surrogates compared to higher temperatures, ultra-cold HPP performed on thawed samples especially enhances inactivation.

Use of Human Intestinal Enteroids for Recovery of Infectious Human Norovirus from Berries and Lettuce

Norovirus (NoV) is the leading cause of viral foodborne gastroenteritis globally. Currently, the gold standard for detecting NoV in clinical, food, and environmental samples is via molecular-based methods, primarily RT-PCR. Nevertheless, there is a great need for confirmatory assays that can determine the infectivity of viral particles recovered from contaminated matrices. The use of the human intestinal enteroids system (HIEs) has allowed for the expansion of norovirus replication, although it still suffers from limitations of strain preferences and the requirement of high titer stocks for infection. In this study, we wanted to explore the feasibility of using the HIEs to support the replication of NoV that had been recovered from representative food matrices that have been associated with foodborne illness. We first confirmed that HIEs can support the replication of several strains of NoV as measured by RT-qPCR. We subsequently chose two of those strains that reproducibly replicated, GII.4 and GII.6, to evaluate in a TCID50 assay and for future experiments. Infectious NoV could be recovered and quantified in the HIEs from lettuce, frozen raspberries, or frozen strawberries seeded with high titers of either of these strains. While many experimental challenges still remain to be overcome, the results of this study represent an important step toward the detection of infectious norovirus from representative produce items.

Research Progress on Biological Accumulation, Detection and Inactivation Technologies of Norovirus in Oysters

Noroviruses (NoVs) are major foodborne pathogens that cause acute gastroenteritis. Oysters are significant carriers of this pathogen, and disease transmission from the consumption of NoVs-infected oysters occurs worldwide. The review discusses the mechanism of NoVs bioaccumulation in oysters, particularly the binding of histo-blood group antigen-like (HBGA-like) molecules to NoVs in oysters. The review explores the factors that influence NoVs bioaccumulation in oysters, including temperature, precipitation and water contamination. The review also discusses the detection methods of NoVs in live oysters and analyzes the inactivation effects of high hydrostatic pressure, irradiation treatment and plasma treatment on NoVs. These non-thermal processing treatments can remove NoVs efficiently while retaining the original flavor of oysters. However, further research is needed to reduce the cost of these technologies to achieve large-scale commercial applications. The review aims to provide novel insights to reduce the bioaccumulation of NoVs in oysters and serve as a reference for the development of new, rapid and effective methods for detecting and inactivating NoVs in live oysters.

The globally re-emerging norovirus GII.2 manifests higher heat resistance than norovirus GII.4 and Tulane virus

AIMS

To compare the heat stability of two globally prevalent human norovirus (HuNoV) strains (GII.2[P16] and GII.4[P16]) and a commonly used HuNoV surrogate, Tulane virus (TV).

METHODS AND RESULTS

With the use of a newly developed zebrafish larvae platform, we measured the change of infectivity of HuNoV GII.2[P16] and GII.4[P16] toward mild heat treatment at 55°C for 5 min. TV was tested with the same experimental design. As a result, the virus infectivity measurement clearly indicated the higher heat resistance of HuNoV GII.2[P16] (no reduction) than GII.4[P16] (>0.8-log TCID₅₀  ml^-1 reduction) and TV (2.5-log TCID₅₀  ml^-1 reduction). Further exploration revealed higher virus structural stability of HuNoV GII.2 than GII.4 strains by the use of different clinical samples with different evaluation methods.

CONCLUSION

The inactivation data generated from the surrogate virus TV cannot be used directly to describe the inactivation of HuNoV. The phylogenetic classification of HuNoVs may correlate with the virus stability and/or circulation dynamics.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study is expected to serve as an important reference when revisiting the numerous previous data evaluating HuNoV inactivation conditions in foods with the use of TV as the cultivable surrogate or with genuine HuNoV but using molecular methods. The higher resistance of NoV GII.2 strains than GII.4 strains toward inactivation treatment supplies a possible explanation for the global re-emerging of NoV GII.2 epidemic in recent years.

Assessment of the Impact on Human Health of the Presence of Norovirus in Bivalve Molluscs: What Data Do We Miss?

In the latest One Health ECDC EFSA technical report, Norovirus in fish and fishery products have been listed as the agent/food pair causing the highest number of strong-evidence outbreaks in the EU in 2019. This review aims to identify data gaps that must be filled in order to increase knowledge on Norovirus in bivalve molluscs, perform a risk assessment and rank the key mitigation strategies for this biological hazard, which is relevant to public health. Virologic determinations are not included in any of the food safety and process hygiene microbiologic criteria reflected in the current European regulations. In addition, the Escherichia coli-based indices of acceptable faecal contamination for primary production, as well as the food safety criteria, do not appear sufficient to indicate the extent of Norovirus contamination. The qualitative risk assessment data collected in this review suggests that bivalve molluscs present a high risk to human health for Norovirus only when consumed raw or when insufficiently cooked. On the contrary, the risk can be considered negligible when they are cooked at a high temperature, while information is still scarce for non-thermal treatments.

Contamination, bioaccumulation mechanism, detection, and control of human norovirus in bivalve shellfish: A review

Human norovirus (HuNoV) is a major foodborne pathogen that causes acute viral gastroenteritis, and bivalve shellfish are one of the main carriers of HuNoV transmission. A comprehensive understanding of bivalve shellfish-related HuNoV outbreaks focusing on contamination factors, bioaccumulation mechanisms, and pre- and post-harvest interventions is essential for the development of effective strategies to prevent contamination of shellfish. This review comprehensively surveys the current knowledge on global contamination and non-thermal treatment of HuNoV in bivalve shellfish. HuNoV contamination in bivalve shellfish is significantly related to the season and water. While evaluating the water quality of shellfish-inhabited waters is a key intervention, the development of non-heat treatment technology to effectively inactivate the HuNoV in bivalve shellfish while maintaining the flavor and nutrition of the shellfish is also an important direction for further research. Additionally, this review explores the bioaccumulation mechanisms of HuNoV in bivalve shellfish, especially the mechanism underlying the binding of histo-blood group antigen-like molecules and HuNoV. The detection methods for infectious HuNoV are also discussed. The establishment of effective methods to rapidly detect infectious HuNoV and development of biological components to inactivate or prevent HuNoV contamination in shellfish also need to be studied further.

Aspects of high hydrostatic pressure food processing: Perspectives on technology and food safety

The last two decades saw a steady increase of high hydrostatic pressure (HHP) used for treatment of foods. Although the science of biomaterials exposed to high pressure started more than a century ago, there still seem to be a number of unanswered questions regarding safety of foods processed using HHP. This review gives an overview on historical development and fundamental aspects of HHP, as well as on potential risks associated with HHP food applications based on available literature. Beside the combination of pressure and temperature, as major factors impacting inactivation of vegetative bacterial cells, bacterial endospores, viruses, and parasites, factors, such as food matrix, water content, presence of dissolved substances, and pH value, also have significant influence on their inactivation by pressure. As a result, pressure treatment of foods should be considered for specific food groups and in accordance with their specific chemical and physical properties. The pressure necessary for inactivation of viruses is in many instances slightly lower than that for vegetative bacterial cells; however, data for food relevant human virus types are missing due to the lack of methods for determining their infectivity. Parasites can be inactivated by comparatively lower pressure than vegetative bacterial cells. The degrees to which chemical reactions progress under pressure treatments are different to those of conventional thermal processes, for example, HHP leads to lower amounts of acrylamide and furan. Additionally, the formation of new unknown or unexpected substances has not yet been observed. To date, no safety-relevant chemical changes have been described for foods treated by HHP. Based on existing sensitization to non-HHP-treated food, the allergenic potential of HHP-treated food is more likely to be equivalent to untreated food. Initial findings on changes in packaging materials under HHP have not yet been adequately supported by scientific data.

Inactivation of norovirus by atmospheric pressure plasma jet on salmon sashimi

This study investigated atmospheric pressure plasma (APP) jet, an emerging novel non-thermal technology, for the inactivation of human norovirus (NoV) on salmon sashimi. The influences of the non-thermal plasma on quality attributes of sashimi were also evaluated. Air, O₂, and N₂ (15 L/min) were used to produce the plasma jets. N₂ plasma treatment for 12 min reduced NoV viral load (VL) (initial inoculums of 2.7 × 10⁴ copies/g) by 2.17 × 10⁴ copies/g, while air-based or O₂-based plasma treatment for 9-12 min could reduce the VL to undetectable levels (below 100 copies/g). Under the same operating condition, the air-based or O₂-based plasma treatment might increase slightly TBARS values in sashimi, yet the values (far below 1.0 mg MDA/kg) were within acceptable level for sashimi made with salmon fishes. The APP jets (APPJ) treatments could also retain the pH of sashimi at normal levels (6.29 ~ 6.02) to maintain the quality of salmon sashimi, the color quality of which was not affected evidently. The plasma-induced hardness and springiness changes in salmon sashimi were substantially low. These results suggested APPJ could be implemented as technology for inactivation of food-borne viruses and exhibited a high potential for application in fish sashimi processing, retaining product quality as well.

Inactivation of Foodborne Viruses by High-Pressure Processing (HPP)

High-pressure processing (HPP) is an innovative non-thermal food preservation method. HPP can inactivate microorganisms, including viruses, with minimal influence on the physicochemical and sensory properties of foods. The most significant foodborne viruses are human norovirus (HuNoV), hepatitis A virus (HAV), human rotavirus (HRV), hepatitis E virus (HEV), human astrovirus (HAstV), human adenovirus (HuAdV), Aichi virus (AiV), sapovirus (SaV), and enterovirus (EV), which have also been implicated in foodborne outbreaks in various countries. The HPP inactivation of foodborne viruses in foods depends on high-pressure processing parameters (pressure, temperature, and duration time) or non-processing parameters such as virus type, food matrix, water activity (aw), and the pH of foods. HPP was found to be effective for the inactivation of foodborne viruses such as HuNoV, HAV, HAstV, and HuAdV in foods. HPP treatments have been found to be effective at eliminating foodborne viruses in high-risk foods such as shellfish and vegetables. The present work reviews the published data on the effect of HPP processing on foodborne viruses in laboratory media and foods.

Foodborne Viruses and Innovative Non-Thermal Food-Processing Technologies

In recent years, several foodborne viruses' outbreaks have been recorded worldwide. Μost of the foodborne viruses have a low infection dose, are stable and can persist and survive in foods for a long time without loss of infectivity. The most important foodborne viruses are: human norovirus (HuNoV), human rotavirus (HRV), hepatitis A virus (HAV), hepatitis E virus (HEV), human astrovirus (HAstV), Aichi virus (AiV), sapovirus (SaV), human adenovirus (HAdV) and enterovirus (EV). In recent years, innovative non-thermal food-processing technologies including high-pressure processing (HPP), cold plasma (CP), ultraviolet light (UV), irradiation and pulsed electric field (PEF) for improving the quality and safety of foods, including foods of animal origin, have been under research. This review presents the recent data on foodborne viruses and reviews the innovative non-thermal technologies for the control of the foodborne viruses in foods.

Evaluation of Copper Alloy Surfaces for Inactivation of Tulane Virus and Human Noroviruses

ABSTRACT

This study evaluated the efficacy of copper alloy surfaces for inactivation of Tulane virus (TV), assessed by plaque assay and porcine gastric mucin-conjugated magnetic bead (PGM-MB) binding assay, followed by quantitative reverse transcription PCR (PGM-MB-RT-qPCR assay). In addition, the efficacy of a copper surface for inactivation of human norovirus (HuNoV) GII.4 Sydney and GI.3B Potsdam strains was evaluated by PGM-MB-RT-qPCR assay. Results of time-dependent inactivation of viruses on copper, bronze, and brass coupons revealed that 15 min of surface treatments of each of the copper and copper alloys achieved >4-log reduction of purified TV, as assessed by plaque assay, while up to 20 min of copper alloy surface treatments only achieved ∼2-log reduction, as assessed by PGM-MB-RT-qPCR assay. As assessed by PGM-MB-RT-qPCR assay, 10 min of copper surface treatments achieved reductions of 3 and 4 log units for HuNoVs GII.4 Sydney and GI.3B Potsdam, respectively. Results from this study suggest that even though PGM-MB-RT-qPCR assay underestimated the efficacy of copper alloy surface inactivation of TV, copper alloy surfaces were able to effectively inactivate TV and HuNoVs. Therefore, copper alloys can be used as a preventive measure to prevent HuNoV infection and are an effective surface treatment for HuNoVs.

HIGHLIGHTS

Evaluation of High-Pressure Processing in Inactivation of the Hepatitis E Virus

Hepatitis E virus (HEV) causes acute hepatitis with approximately 20 million cases per year globally. Based on genetic diversity, HEV is classified into different genotypes, with genotype 3 (HEV-3) being most prevalent in Europe and North America. The transmission of HEV-3 has been shown to be zoonotic and mainly associated with the consumption of raw or undercooked pork products. Herein, we investigated the efficacy of high-pressure processing (HPP) in inactivation of HEV-3 using a cell culture system. HPP has been indicated as a promising non-thermal pathogen inactivation strategy for treatment of certain high-risk food commodities, without any noticeable changes in their nature. For this purpose, we treated HEV-3 in media with different conditions of HPP: 400 MPa for 1 and 5 min, as well as 600 MPa for 1 and 5 min, at ambient temperature. All four HPP treatments of HEV in media were observed to result in a 2-log reduction in HEV load, as determined by the amounts of extracellular HEV RNA produced at 14-day post-infection, using the A549/D3 cell culture system. However, application of the same treatments to artificially contaminated pork pâté resulted in 0.5 log reduction in viral load. These results indicate that the efficacy of HPP treatment in the inactivation of HEV-3 is matrix-dependent, and independent of maximum pressure between 400 and 600 MPa and hold time between 1 and 5 min. Based on the obtained results, although the HPP treatment of pork pâté reduces the HEV-3 load, it might not be sufficient to fully mitigate the risk.

Norovirus: The Burden of the Unknown

Human noroviruses (HNoVs) are primarily transmitted by the fecal-oral route, either by person-to-person contact, or by ingestion of contaminated food or water as well as by aerosolization. Moreover, HNoVs significantly contribute to foodborne diseases being the causative agent of one-fifth of acute gastroenteritis worldwide. As a consequence of globalization, transnational outbreaks of foodborne infections are reported with increasing frequency. Therefore, in this review, state-of-the-art information regarding molecular procedures for human norovirus detection in food as well common food processing technologies have been summarized. Besides, the purpose of this chapter is to consolidate basic information on various aspects of HNoVs and to summarize food processing technologies that can potentially be applied in the food industry.