Extraction of human noroviruses from leafy greens and fresh herbs using magnetic silica beads. (October 2021)

• Record Type: Journal Article
• Authors: Raymond, Philippe; Paul, Sylvianne; Perron, André; Deschênes, Louise; Hara, Kenji
• Is Part Of: Food microbiology. Volume 99(2021)
• Publication Date: 2021-10
• Subjects: Norovirus -- Lettuce -- Fresh herbs -- RNA extraction -- Silica -- PCR inhibitors -- Process control -- Capsid integrity; Food Microbiology -- Periodicals; Aliments -- Microbiologie -- Périodiques; Food -- Microbiology; Periodicals; Food -- Microbiology -- Periodicals; Food contamination -- Periodicals; 664.001579
• DOI: 10.1016/j.fm.2021.103827
• Languages: English
• ISSNs: 0740-0020

Abstract

Abstract: Consumption of leafy greens and to a lesser extent fresh herbs has been associated with several foodborne outbreaks including human norovirus (HuNoV). However, the extraction and detection of viruses from these matrices present multiple challenges such as low recovery yields and relatively high PCR inhibition. A new magnetic silica bead based (MSB) extraction protocol was developed and used to recover norovirus from leafy greens and fresh herbs. The performance results were compared to the ISO 15216–1:2017 standard. The HuNoV GII.4 and GI.5 recovery yields from spiked lettuce using the MSB extraction protocol range from 33 to 82%. There was a good correlation between murine norovirus (MNV) and HuNoV recovery yields from fresh herbs and leafy greens. No reverse-transcriptase quantitative polymerase chain reaction (RT-qPCR) inhibition was detected from leafy green extracts using the MSB methodology. The selected commercial RT-qPCR detection kit had a major impact on RT-qPCR inhibition levels detected in the ISO 15216–1:2017 RNA extracts. RNase treatment was used to estimate genome recovery from HuNoV with intact capsids. This treatment resulted in similar HuNoV and MNV recovery yields. Between 2019 and 2020, the MSB protocol was used to conduct a survey of HuNoV in domestic and imported leafy greens and fresh herbs sold at retail in Canada. All of the 280 samples tested were negative. Overall, the use of MSB was shown to be an efficient approach to recover HuNoV from leafy greens and certain types of fresh herbs and to conduct surveys. Highlights: Magnetic silica bead methodology efficiently recovers human norovirus from leafy greens . No RT-qPCR inhibition detected from leafy green extracts using MSB . RT-qPCR inhibition associated to ISO 15216-1:2017 protocol could be corrected using the selected RT-qPCR detection kit. A correlation between murine and human norovirus recovery from fresh herbs and leafy greens was observed. No human norovirus in 280 Canadian retail leafy greens and fresh herbs .