Enhanced immunomagnetic separation for the detection of norovirus using the polyclonal antibody produced with human norovirus GII.4-like particles

Subtype specific virus enrichment with immunomagnetic separation method followed by NGS unravels the mixture of H5 and H9 avian influenza virus

Wild bird avian influenza type A virus (AIV) surveillance is important for the early detection of highly pathogenic AIVs and for providing early warnings to the poultry industry and veterinary services to implement more effective control measures against these viruses. Some field samples are often found to contain more than two kinds of AIV. Correct determination of the HA/NA subtype and complete nucleotide sequences of the component viruses in those samples are often critical for timely and accurate understanding of the field situation, but it is not easy to define the genomic structure of the constituent viruses unambiguously because AIV has eight segmented genomes. In this study, with immunomagnetic beads incorporating polyclonal antibodies of chicken for subtype-specific viral enrichment, we could selectively decrease the density of one of the two constituent viruses in a sample of different subtypes, H5 and H9, artificially generated; this was represented in the changes of Ct values with subtype specific real-time RT-PCR. Following this, with NGS, we could recover nearly complete genomic sequences and arrange the consensus sequences of gene segments of the constituent viruses confidently with the quantitative variable like genome coverage, linked along the gene segments and associated with the number of viral copies in a sample.

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.

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.