Li Xinhui, Huang Runze, Chen Haiqiang
Department of Microbiology, University of Wisconsin-La Crosse, La Crosse, WI, 54601, USA.
Department of Animal & Food Sciences, University of Delaware, Newark, DE, 19716-2150, USA.
Food Environ Virol. 2017 Sep;9(3):314-325. doi: 10.1007/s12560-017-9288-2. Epub 2017 Feb 25.
We compared the heat and high hydrostatic pressure (HHP) inactivation results of Tulane virus (TV), a human norovirus (HuNoV) surrogate, obtained by plaque assay, direct quantitative reverse transcription PCR (RT-qPCR), porcine gastric mucin magnetic beads (PGM-MBs) binding assay followed by RT-qPCR (PGM/PCR), and propidium monoazide (PMA) assay followed by RT-qPCR (PMA/PCR). Heat and HHP inactivation of a HuNoV genotype I.1 (GI.1) strain and a genotype II.4 (GII.4) strain was also evaluated using those molecular assays. Viruses were heat treated at 50-90 °C for 2 min and HHP treated at 100-550 MPa at initial temperatures of 4 or 21 °C for 2 min. For heat treatment, the three molecular methods significantly underestimated the inactivation of TV. It could be logically concluded that the PGM/PCR assay was better than the PMA/PCR and direct RT-qPCR assays in estimating the inactivation of HuNoV GI.1. The three molecular methods were comparable in estimating the heat inactivation of GII.4. For HHP treatment, both PGM/PCR and PMA/PCR assays were able to estimate inactivation of TV at ≤2-log reduction levels, but significantly underestimated its inactivation at >2-log reduction levels. The direct RT-qPCR assay was the worst method for estimating HHP inactivation of TV. It could be logically concluded that the PGM/PCR and PMA/PCR assays were comparable in estimating the HHP inactivation of GI.1 and both were significantly better than the direct RT-qPCR assay. Among the three molecular methods, the PGM/PCR assay was the best in estimating the HHP inactivation of GII.4. These results demonstrated that the PGM/PCR assay was probably the method of choice in estimating the inactivation of HuNoV GI.1 and GII.4 for heat and HHP treatments, but this method would likely result in underestimation of HuNoV inactivation.
我们比较了通过噬斑测定、直接定量逆转录聚合酶链反应（RT-qPCR）、猪胃粘蛋白磁珠（PGM-MBs）结合测定后进行RT-qPCR（PGM/PCR）以及单叠氮化丙锭（PMA）测定后进行RT-qPCR（PMA/PCR）所获得的杜兰病毒（TV，一种人诺如病毒（HuNoV）替代物）的热灭活和高静水压（HHP）灭活结果。还使用这些分子测定方法评估了HuNoV基因型I.1（GI.1）毒株和基因型II.4（GII.4）毒株的热灭活和HHP灭活情况。病毒在50 - 90°C下热处理2分钟，并在4或21°C的初始温度下在100 - 550MPa下进行HHP处理2分钟。对于热处理，这三种分子方法显著低估了TV的灭活情况。可以合理推断，在估计HuNoV GI.1的灭活情况时，PGM/PCR测定法优于PMA/PCR和直接RT-qPCR测定法。在估计GII.4的热灭活情况时，这三种分子方法具有可比性。对于HHP处理，PGM/PCR和PMA/PCR测定法都能够估计TV在≤2个对数减少水平的灭活情况，但在>2个对数减少水平时显著低估了其灭活情况。直接RT-qPCR测定法是估计TV的HHP灭活情况最差的方法。可以合理推断，在估计GI.1的HHP灭活情况时，PGM/PCR和PMA/PCR测定法具有可比性，且两者都明显优于直接RT-qPCR测定法。在这三种分子方法中，PGM/PCR测定法在估计GII.4的HHP灭活情况时是最好的。这些结果表明，PGM/PCR测定法可能是估计HuNoV GI.1和GII.4在热和HHP处理下灭活情况的首选方法，但这种方法可能会导致对HuNoV灭活情况的低估。
