Abstract Title
Evaluation of heat inactivation of human norovirus using two distinct cultivation systems
Presenter
Kosuke Murakami, Japan Institute for Health Security
Co-Author(s)
Kosuke Murakami1,2, Tsuyoshi Hayashi2, Fuka Kagimoto3, Shigeyuki Tamiya3, Naomi Sakon4, Tomoko Takahashi5, Akie Sakagami6, Masashi Uema7, Shintaro Sato3
1. Department of Diagnostic Testing and Technology Research, Japan Institute for Health Security, Japan
2. Department of Virology II, Japan Institute for Health Security, Japan
3. Department of Microbiology and Immunology, School of Pharmaceutical Sciences, Wakayama Medical University, Japan.
4. Virology Section, Osaka Institute of Public Health, Japan.
5. Iwate Prefectural Research Institute for Environmental Science and Public Health, Japan.
6. Department of Microbiology, Miyagi Prefectural Institute of Public Health and Environment, Japan.
7. Division of Biomedical Food Research, National Institute of Health Sciences.
Abstract Category
Food & Environmental Virology-I (Food)
Abstract
Human norovirus (HuNoV) is the leading cause of foodborne illness outbreaks over the world. However, the efficacy of inactivation parameters for HuNoV remains incompletely defined due to the lack of cultivation systems until recently. In the current study, two HuNoV cultivation systems, stem cell-derived human intestinal organoids (HIOs) and human-induced pluripotent stem cell-derived intestinal epithelial cells (IECs), in distinct institutes were adopted for heat inactivation of HuNoV.
Two GII.4 stool samples were distributed to each institute to be subjected to HIOs and IECs, independently. First, HuNoVs added into 1 mL of medium in 1.5 mL microtubes were heated in a dry heat block at 85oC for 1~5 minutes and inoculated with HIOs, in which viral copies were measured by RT-qPCR. Although the result showed that heating for 1 minute is sufficient to lack infectivity of HuNoV in 1.5 mL tubes, we found that the temperature of the medium required at least 3 minutes to reach 85oC. Thus, we next performed the same experiment using PCR tubes and a thermal cycler, which heated 30 microL of medium within 45 seconds, to avoid an effect of thermal conductivity. As the above experiments, two GII.4s lost infectivity to both HIOs and IECs by heating for 1 minute. Although replication of GII.4 in HIOs was completely decreased by heating at 60oC for 1 minute, that in IECs slightly remained at 60oC for 15 minutes. Taken together, we demonstrated that GII.4 was inactivated by heating at 85oC for 1 minute.
Two GII.4 stool samples were distributed to each institute to be subjected to HIOs and IECs, independently. First, HuNoVs added into 1 mL of medium in 1.5 mL microtubes were heated in a dry heat block at 85oC for 1~5 minutes and inoculated with HIOs, in which viral copies were measured by RT-qPCR. Although the result showed that heating for 1 minute is sufficient to lack infectivity of HuNoV in 1.5 mL tubes, we found that the temperature of the medium required at least 3 minutes to reach 85oC. Thus, we next performed the same experiment using PCR tubes and a thermal cycler, which heated 30 microL of medium within 45 seconds, to avoid an effect of thermal conductivity. As the above experiments, two GII.4s lost infectivity to both HIOs and IECs by heating for 1 minute. Although replication of GII.4 in HIOs was completely decreased by heating at 60oC for 1 minute, that in IECs slightly remained at 60oC for 15 minutes. Taken together, we demonstrated that GII.4 was inactivated by heating at 85oC for 1 minute.