Survivability of MNV and MS2 on Either Wood or Stainless Steel Surfaces at Various Temperature and Relative Humidity

Introduction: Norovirus (NoV) is one of the common causes of non-bacterial acute gastroenteritis. They are known to persist on food-contact surfaces for prolonged periods, which lead to cross contamination of foods and foodborne diseases. Hence, we characterized the survival of murine norovirus (MNV) as a surrogate of human norovirus (HuNoV) and bacteriophage MS2 on wood or stainless steel surface under temperatures (4, 15, 25, 32, and 40°C) and relative humidity (30, 50, and 70%).

Purpose: To characterize the inactivation curves of MNV and MS2 under different environment conditions.

Methods: About 10⁸ PFU/ml was inoculated, sampled at predetermined time over 30 days, and analyzed by both plaque and real-time RT-PCR assays. The Weibull model and D-value were used to describe inactivation in the environmental conditions.

Results: Both MNV and MS2 survived better on wood surface than stainless steel. As both temperature and RH increased, both MS2 and MNV were inactivated more rapidly. For example, more than a 4-log reduction of MNV occurred on stainless steel surface at 40 and 70% RH within 9 hours. However, only about a 2-log reduction of MNV occurred on wood surface at 25 and 30% RH over 30 days. Regardless of tested conditions, viral RNA was persistent without any significant reduction.

Significance: Our results demonstrated that both surface characteristics and environments could influence viral survivability.