Immunomagnetic separation combined with RT-qPCR for determining the efficacy of disinfectants against human noroviruses

Recent trends and developments of PCR-based methods for the detection of food-borne Salmonella bacteria and Norovirus

In recent years, rapid detection methods such as polymerase chain reaction (PCR) and quantitative real-time PCR (qPCR) have been continuously developed to improve the detection of food-borne pathogens in food samples. The recent developments of PCR and qPCR in the detection and identification of these food-borne pathogens are described and elaborated throughout this review. Specifically, further developments and improvements of qPCR are discussed in detecting Salmonella and norovirus. Promising advances in these molecular detection methods have been widely used to prevent human food-borne illnesses and death caused by the food-borne pathogens. In addition, this review presents the limitations and challenges of the detection methods which include conventional culture method and conventional PCR method in detecting Salmonella and norovirus. Furthermore, several advances of qPCR such as viability PCR (vPCR) and digital PCR (dPCR) have been discussed in the detection of Salmonella and norovirus. Good practice of analysis of the food-borne pathogens and other contaminants in the food industry as well as the advancement of molecular detection methods will help improve and ensure food safety and food quality.

Risks and new challenges in the food chain: Viral contamination and decontamination from a global perspective, guidelines, and cleaning

Even during the continuing world pandemic of severe acute respiratory syndrome coronavirus 2 (SARS CoV-2), consumers remain exposed to the risk of getting infected by existing, emerging, or re-emerging foodborne and waterborne viruses. SARS-CoV-2 is different in that it is transmitted directly via the airborne route (droplets and aerosols) or indirect contact (surfaces contaminated with SARS-CoV-2). International food and health organizations and national regulatory bodies have provided guidance to protect individuals active in food premises from potential occupational exposure to SARS-CoV-2, and have recommended chemicals effective in controlling the virus. Additionally, to exclude transmission of foodborne and waterborne viruses, hygiene practices to remove viral contaminants from surfaces are applied in different stages of the food chain (e.g., food plants, food distribution, storage, retail sector, etc.), while new and enhanced measures effective in the control of all types of viruses are under development. This comprehensive review aims to analyze and compare efficacies of existing cleaning practices currently used in the food industry to remove pathogenic viruses from air, nonfood, and food contact surfaces, as well as from food surfaces. In addition, the classification, modes of transmission, and survival of food and waterborne viruses, as well as SARS-CoV-2 will be presented. The international guidelines and national regulations are summarized in terms of virucidal chemical agents and their applications.

Determining the efficacy of 27 commercially available disinfectants against human noroviruses

BACKGROUND

Recently, monoclonal-antibody-conjugated immunomagnetic separation (IMS) procedure combined with quantitative reverse transcription-polymerase chain reaction (qRT-PCR) has been used for quantifying non-cultivated human noroviruses (HuNoVs).

METHODS

We examined the efficacy of 27 commercially available disinfectants and a prototype against GII.4 strain HuNoV through the IMS/qRT-PCR assay.

RESULTS

The average log reduction in viral titer in vitro varied among the disinfectants. The prototype was the most effective with an average log reduction of 6.86 log.

CONCLUSIONS

The IMS/RT-qPCR assay is an effective method to evaluate the activities of disinfectants against GII.4 HuNoV in vitro. Further work is needed to enhance the virucidal activity of the prototype disinfectant against more resistant HuNoV strains.

Assessment of human norovirus inhibition in cabbage kimchi by electron beam irradiation using RT-qPCR combined with immunomagnetic separation

Cabbage Kimchi, a traditional Korean fermented food, has occasionally been related to acute gastroenteritis caused by human norovirus (HuNoV). The present study examined the inhibitory effects of electron beam (e-beam) irradiation (1, 3, 5, 7, and 10 kGy) on HuNoV GII.4 in suspension or cabbage Kimchi using reverse transcription quantitative polymerase chain reaction combined with immunomagnetic separation (IMS/RT-qPCR). In addition, physicochemical and sensorial analyses were conducted to assess any change in the quality of cabbage Kimchi following e-beam irradiation. Following e-beam irradiation at 1 to 10 kGy, HuNoV significantly decreased to 0.28 to 2.08 log₁₀ copy number/mL in suspension (P < 0.05). HuNoV levels in cabbage Kimchi were also significantly reduced to 0.26 to 1.57 log₁₀ copy number/mL following irradiation with 1 to 10 kGy (P < 0.05) compared to positive control (6.0 log₁₀ copy number/mL). The D-values for 1 log₁₀ reduction (90% inhibition) of HuNoV in suspension and cabbage Kimchi were 4.94 and 6.96 kGy of e-beam, respectively. The pH and acidity in the irradiated cabbage Kimchi were 4.41 to 4.58 and 0.61% to 0.71%, respectively, indicating that e-beam did not affect the optimal pH or acidity. Although a slight increase of greenness was observed in the leaf portion of cabbage Kimchi irradiated with 7 to 10 kGy of e-beam, this color change was minimal and went undetected by panelists in the sensorial evaluation. The five properties of sensorial quality assessed were no different in the irradiated Kimchi sample compared with the control sample (nonirradiated cabbage Kimchi). Therefore, this study suggests that ≥6.96 kGy of e-beam could be applied in the cabbage Kimchi industry to obtain >90% of HuNoV without affecting the quality. PRACTICAL APPLICATION: As the most representative food in Korea, Kimchi needs the sanitation technology that can inhibit viral infection. Our findings suggest that e-beam irradiation can be used to reduce HuNoV effectively in Kimchi without changes in sensorial quality.

Antimicrobial Coatings for Food Contact Surfaces: Legal Framework, Mechanical Properties, and Potential Applications

Food contact surfaces (FCS) in food processing facilities may become contaminated with a number of unwanted microorganisms, such as Listeria monocytogenes, Escherichia coli O157:H7, and Staphylococcus aureus. To reduce contamination and the spread of disease, these surfaces may be treated with sanitizers or have active antimicrobial components adhered to them. Although significant efforts have been devoted to the development of coatings that improve the antimicrobial effectiveness of FCS, other important coating considerations, such as hardness, adhesion to a substrate, and migration of the antimicrobial substance into the food matrix, have largely been disregarded to the detriment of their translation into practical application. To address this gap, this review examines the mechanical properties of antimicrobial coatings (AMC) applied to FCS and their interplay with their antimicrobial properties within the framework of relevant regulatory constraints that would apply if these were used in real-world applications. This review also explores the various assessment techniques for examining these properties, the effects of the deposition methods on coating properties, and the potential applications of such coatings for FCS. Overall, this review attempts to provide a holistic perspective. Evaluation of the current literature urges a compromise between antimicrobial effectiveness and mechanical stability in order to adhere to various regulatory frameworks as the next step toward improving the industrial feasibility of AMC for FCS applications.

Point-of-Care Strategies for Detection of Waterborne Pathogens

Waterborne diseases that originated due to pathogen microorganisms are emerging as a serious global health concern. Therefore, rapid, accurate, and specific detection of these microorganisms (i.e., bacteria, viruses, protozoa, and parasitic pathogens) in water resources has become a requirement of water quality assessment. Significant research has been conducted to develop rapid, efficient, scalable, and affordable sensing techniques to detect biological contaminants. State-of-the-art technology-assisted smart sensors have improved features (high sensitivity and very low detection limit) and can perform in a real-time manner. However, there is still a need to promote this area of research, keeping global aspects and demand in mind. Keeping this view, this article was designed carefully and critically to explore sensing technologies developed for the detection of biological contaminants. Advancements using paper-based assays, microfluidic platforms, and lateral flow devices are discussed in this report. The emerging recent trends, mainly point-of-care (POC) technologies, of water safety analysis are also discussed here, along with challenges and future prospective applications of these smart sensing technologies for water health diagnostics.

Immunomagnetic enrichment to evaluate the role of home environment specimens in transmission of enterovirus 71

Enterovirus 71 (EV71) immunomagnetic enrichment technique and routine detection methods were combined to detect swab environmental specimens to elucidate the role of environmental specimens in the spread of EV71. Immunomagnetic beads with specific enrichment of EV71 virus were prepared, then the beads were used to absorb the EV71 virus from environmental samples. Obtained immunomagnetic bead-virus complexes were detected by RT-PCR, RT-qPCR and cell culture. Isolated virus were subjected to VP1 full-length amplification and homology analysis was performed. A total of 4 µg of EV71 monoclonal antibody was mixed with 50 µl magnetic beads, and the highest coating efficiency was reached after incubating at room temperature for 2 h. Satisfactory enrichment effect was achieved by adding 50 µl immunomagnetic beads to 1.5 ml sample and shaking at room temperature for 2 h. The method of EV71 enrichment has high sensitivity and specificity. A total of 346 specimens after enrichment by immunomagnetic beads, the positive rates of RT-qPCR, RT-PCR and cell culture were 20.52, 5.78, and 9.25%, respectively, which were also significantly higher than those before enrichment (15.90, 3.47 and 4.05%; P<0.05). After enrichment with immunomagnetic beads, isolation rate of EV71 virus from case specimens and home environment specimens increased from 27.45 to 43.14% and from 0 to 5.29%, respectively. In home environment-positive specimens, positive rate of toys and stationery was high (52.00 and 24.00%, respectively). In kindergarten environmental samples, the positive rate of RT-qPCR was 6.12%, and EV71 virus was not isolated. Sequence analysis showed that the nucleotide homology of case isolates and home environment isolates was 98.0–100%.

Efficacy of Combination Treatment with Sodium Metasilicate and Sodium Hypochlorite for Inactivation of Norovirus on Fresh Vegetables

In recent years, fresh vegetables have frequently been associated with the foodborne transmission of enteric viruses, such as human norovirus (NoV). Therefore, several studies have focused on developing methods to inactivate foodborne viruses for preventing outbreaks of foodborne illnesses. Sodium hypochlorite (NaOCl) is commonly used as a disinfectant, but results in undesirable effects on the appearance and taste of foods and can generate toxic byproducts when it exceeds the allowable concentration. Here, we evaluated the efficacy of a range of NaOCl concentrations (50-1000 ppm) for reducing the amounts of human NoV (NoV GII.4) on lettuce (Lactuca sativa), celery (Apium graveolens L.), and white cabbage (Brassica oleracea ssp. capitata). In addition, the combination treatment of NaOCl and sodium metasilicate (SMS, 0.1-0.5%) pentahydrate was evaluated for its ability to decrease the populations of NoV GII.4 in the three food samples. An immunomagnetic separation procedure combined with reverse transcription quantitative polymerase chain reaction was used for virus detection. For lettuce, celery, and cabbage, the NoV GII.4 recovery rates were 57.3% ± 6.5%, 52.5% ± 1.7%, and 60.3% ± 3.9%, respectively, using a glycine/NaCl elution buffer (0.25 M glycine/0.14 M NaCl, pH 9.5). The reductions of NoV GII.4 were 3.17, 3.06, and 3.27 log10 genomic copies/μL for lettuce, celery, and cabbage, respectively, at 1000 ppm NaOCl, while a reduction of ∼3 log10 genomic copies/μL was obtained when the samples were treated with a combination of 100 ppm NaOCl and 0.4% SMS pentahydrate. Taken together, these results demonstrated that combined treatment with NaOCl and SMS pentahydrate was an efficient strategy to reduce the concentration of NaOCl for control of NoV GII.4 contamination in fresh vegetables.

Prevalence and evaluation strategies for viral contamination in food products: Risk to human health-a review

Nowadays, viruses of foodborne origin such as norovirus and hepatitis A are considered major causes of foodborne gastrointestinal illness with widespread distribution worldwide. A number of foodborne outbreaks associated with food products of animal and non-animal origins, which often involve multiple cases of variety of food streams, have been reported. Although several viruses, including rotavirus, adenovirus, astrovirus, parvovirus, and other enteroviruses, significantly contribute to incidence of gastrointestinal diseases, systematic information on the role of food in transmitting such viruses is limited. Most of the outbreak cases caused by infected food handlers were the source of 53% of total outbreaks. Therefore, prevention and hygiene measures to reduce the frequency of foodborne virus outbreaks should focus on food workers and production site of food products. Pivotal strategies, such as proper investigation, surveillance, and reports on foodborne viral illnesses, are needed in order to develop more accurate measures to detect the presence and pathogenesis of viral infection with detailed descriptions. Moreover, molecular epidemiology and surveillance of food samples may help analysis of public health hazards associated with exposure to foodborne viruses. In this present review, we discuss different aspects of foodborne viral contamination and its impact on human health. This review also aims to improve understanding of foodborne viral infections as major causes of human illness as well as provide descriptions of their control and prevention strategies and rapid detection by advanced molecular techniques. Further, a brief description of methods available for the detection of viruses in food and related matrices is provided.

Virucidal Activity of Fogged Chlorine Dioxide- and Hydrogen Peroxide-Based Disinfectants against Human Norovirus and Its Surrogate, Feline Calicivirus, on Hard-to-Reach Surfaces

Human norovirus (NoV) is the leading cause of foodborne illnesses in the United States. Norovirus is shed in high numbers in the feces and vomitous of infected individuals. Contact surfaces contaminated with bodily fluids harboring infectious virus particles serve as vehicles for pathogen transmission. Environmental stability of NoV and its resistance to many conventional disinfectants necessitate effective inactivation strategies to control the spread of virus. We investigated the efficacy of two commercial disinfectants, hydrogen peroxide (7.5%) and a chlorine dioxide (0.2%)-surfactant-based product using a fogging delivery system against human NoV GI.6 and GII.4 Sydney strains as well as the cultivable surrogate, feline calicivirus (FCV) dried on stainless steel coupons. Log₁₀ reductions in human NoV and FCV were calculated utilizing RNase RT-qPCR and infectivity (plaque) assay, respectively. An improved antiviral activity of hydrogen peroxide as a function of disinfectant formulation concentration in the atmosphere was observed against both GII.4 and FCV. At 12.4 ml/m³, hydrogen peroxide achieved a respective 2.5 ± 0.1 and 2.7 ± 0.3 log₁₀ reduction in GI.6 and GII.4 NoV genome copies, and a 4.3 ± 0.1 log₁₀ reduction in infectious FCV within 5 min. At the same disinfectant formulation concentration, chlorine dioxide-surfactant-based product resulted in a respective 1.7 ± 0.2, 0.6 ± 0.0, and 2.4 ± 0.2 log₁₀ reduction in GI.6, GII.4, and FCV within 10 min; however, increasing the disinfectant formulation concentration to 15.9 ml/m³ negatively impacted its efficacy. Fogging uniformly delivered the disinfectants throughout the room, and effectively decontaminated viruses on hard-to-reach surfaces. Hydrogen peroxide delivered by fog showed promising virucidal activity against FCV by meeting the United States EPA 4-log₁₀ reduction criteria for an anti-noroviral disinfectant; however, fogged chlorine dioxide-surfactant-based product did not achieve a 4-log₁₀ inactivation. Future investigation aimed at optimizing decontamination practices is warranted.