Department of Animal and Food Sciences, Townsend Hall, University of Delaware, Newark, Delaware 19716, USA.
J Food Prot. 2013 Jan;76(1):139-43. doi: 10.4315/0362-028X.JFP-12-216.
Viral surrogates are widely used by researchers to predict human norovirus behavior. Murine norovirus (MNV) is currently accepted as the best surrogate and is assumed to mimic the survival and inactivation of human noroviruses. Recently, a new calicivirus, the Tulane virus (TV), was discovered, and its potential as a human norovirus surrogate is being explored. This study aimed to compare the behavior of the two potential surrogates under varying treatments of pH (2.0 to 10.0), chlorine (0.2 to 2,000 ppm), heat (50 to 75°C), and survival in tap water at room (20°C) and refrigeration (4°C) temperatures for up to 30 days. Viral infectivity was determined by the plaque assay for both MNV and TV. There was no significant difference between the inactivation of MNV and TV in all heat treatments, and for both MNV and TV survival in tap water at 20°C over 30 days. At 4°C, MNV remained infectious over 30 days at a titer of approximately 5 log PFU/ml, whereas TV titers decreased significantly by 5 days. MNV was more pH stable, as TV titers were reduced significantly at pH 2.0, 9.0, and 10.0, as compared with pH 7.0, whereas MNV titers were only significantly reduced at pH 10.0. After chlorine treatment, there was no significant difference in virus with the exception of at 2 ppm, where TV decreased significantly compared with MNV. Compared with TV, MNV is likely a better surrogate for human noroviruses, as MNV persisted over a wider range of pH values, at 2 ppm of chlorine, and without a loss of titer at 4°C.
病毒替代物被研究人员广泛用于预测人类诺如病毒的行为。鼠诺如病毒（MNV）目前被认为是最佳替代物，被认为可模拟人类诺如病毒的存活和失活。最近，一种新的杯状病毒，即图兰病毒（TV）被发现，其作为人类诺如病毒替代物的潜力正在被探索。本研究旨在比较这两种潜在替代物在不同 pH 值（2.0 至 10.0）、氯（0.2 至 2000 ppm）、热（50 至 75°C）处理以及在室温（20°C）和冷藏（4°C）自来水中存活 30 天的行为。通过噬斑试验测定 MNV 和 TV 的病毒感染力。在所有热处理中，MNV 和 TV 的失活没有显著差异，在 20°C 的自来水中，MNV 和 TV 均可存活 30 天。在 4°C 下，MNV 在 30 天内的滴度保持在约 5 log PFU/ml，而 TV 滴度在 5 天内显著下降。MNV 更耐 pH 值变化，与 pH 值为 7.0 相比，当 pH 值为 2.0、9.0 和 10.0 时，TV 滴度显著降低，而 MNV 滴度仅在 pH 值为 10.0 时显著降低。经过氯处理后，病毒滴度没有显著差异，但在 2 ppm 时，TV 与 MNV 相比显著降低。与 TV 相比，MNV 可能是人类诺如病毒更好的替代物，因为 MNV 在更宽的 pH 值范围、2 ppm 的氯以及在 4°C 下不降低滴度的情况下仍能存活。
