Department of Food Science and Technology, University of Tennessee, 2605 River Drive, Knoxville, Tennessee 37996-4591, USA.
J Food Prot. 2013 Jan;76(1):79-84. doi: 10.4315/0362-028X.JFP-12-327.
Studies are needed to bridge existing data gaps and determine appropriate parameters for thermal inactivation methods for human noroviruses. Cultivable surrogates, such as feline calicivirus (FCV-F9) and murine norovirus (MNV-1), have been used in the absence of human norovirus infectivity assays. This study aimed to characterize the thermal inactivation kinetics of MNV-1 and FCV-F9 at 50, 56, 60, 65, and 72°C for different treatment times (0 to 60 min). Thermal inactivation was performed using the capillary tube method with titers of 4.0 × 10(7) (MNV-1) and 5.8 × 10(8) (FCV-F9) PFU/ml in triplicate experiments, followed by standard plaque assays in duplicate for each experiment. Weibull and first-order models were compared to describe survival curve kinetics. Model fitness was investigated by comparing the regression coefficients (R(2)) and the chi-square (χ(2)) and root mean square error (RMSE) values. The D-values calculated from the first-order model (50 to 72°C) were 0.15 to 34.49 min for MNV-1 and 0.11 to 20.23 min for FCV-9. Using the Weibull model, the t(D) values needed to destroy 1 log PFU of MNV-1 and FCV-F9 at the same temperatures were 0.11 to 28.26 and 0.06 to 13.86 min, respectively. In terms of thermal resistance, MNV-1 was more sensitive than FCV-F9 up to 65°C. At 72°C, FCV-F9 was slightly more susceptible to heat inactivation. Results revealed that the Weibull model was more appropriate to represent the thermal inactivation behavior of both tested surrogates. The z-values were calculated using D-values for the first-order model and the t(D) values for the Weibull model. The z-values were 9.31 and 9.19°C for MNV-1 and 9.36 and 9.31°C for FCV-F9 for the first-order and Weibull models, respectively. This study provides more precise information than previous reports on the thermal inactivation kinetics of two norovirus surrogates for use in thermal process calculations.
需要开展研究以弥合现有数据差距，并确定人类诺如病毒热力灭活方法的适宜参数。在无法进行人类诺如病毒感染力检测的情况下，曾使用可培养的替代物，如猫杯状病毒（FCV-F9）和鼠诺如病毒（MNV-1）。本研究旨在对 50、56、60、65 和 72°C 下不同处理时间（0 至 60 分钟）的 MNV-1 和 FCV-F9 的热力灭活动力学进行特征描述。采用毛细管所规定的方法，对 4.0×10(7)（MNV-1）和 5.8×10(8)（FCV-F9）PFU/ml 的病毒悬液进行 3 次重复试验，并对每个试验各进行 2 次标准蚀斑试验。对比威布尔和一级模型，以描述生存曲线动力学。通过比较回归系数（R(2)）、卡方（χ(2)）和均方根误差（RMSE）值，评估模型拟合度。一级模型（50 至 72°C）计算得到的 D 值分别为 0.15 至 34.49 分钟和 0.11 至 20.23 分钟。威布尔模型计算得到的 t(D)值分别为 0.11 至 28.26 分钟和 0.06 至 13.86 分钟，用于在相同温度下破坏 1 对数毫帕诺病毒和 FCV-F9 的 1 个 PFU。就耐热性而言，MNV-1 对热的敏感性在 65°C 以下高于 FCV-F9。72°C 时，FCV-F9 对热失活的敏感性略有增加。结果表明，威布尔模型更适合描述两种测试替代物的热力灭活行为。通过一级模型的 D 值和威布尔模型的 t(D)值计算 Z 值。一级模型和威布尔模型的 MNV-1 的 Z 值分别为 9.31°C 和 9.19°C，FCV-F9 的 Z 值分别为 9.36°C 和 9.31°C。本研究提供了比以往报告更精确的信息，有助于在热力处理计算中使用两种诺如病毒替代物的热力失活动力学。
