Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
Food Environ Virol. 2024 Sep;16(3):329-337. doi: 10.1007/s12560-024-09595-2. Epub 2024 May 2.
Human norovirus is transmitted mainly via the faecal-oral route, but norovirus disease outbreaks have been reported in which airborne transmission has been suggested as the only explanation. We used murine norovirus (MNV) as a surrogate for human norovirus to determine the aerosolization of infectious norovirus in an experimental setup. A 3-l air chamber system was used for aerosolization of MNV. Virus in solution (6 log TCID/ml) was introduced into the nebulizer for generating aerosols and a RAW 264.7 cell dish without a lid was placed in the air chamber. Cell culture medium samples were taken from the dishes after the aerosol exposure time of 30 or 90 min, and the dishes were placed in a 37 °C, 5% CO incubator and inspected with a light microscope for viral cytopathic effects (CPEs). We determined both the infectious MNV TCID titre and used an RT-qPCR assay. During the experiments, virus infectivity remained stable for 30 and 90 min in the MNV solution in the nebulizer. Infectious MNV TCID values/ml of 2.89 ± 0.29 and 3.20 ± 0.49 log were measured in the chamber in RAW 264.7 cell dish media after the 30-min and 90-min exposure, respectively. The MNV RNA loads were 6.20 ± 0.24 and 6.93 ± 1.02 log genome copies/ml, respectively. Later, a typical MNV CPE appeared in the aerosol-exposed RAW cell dishes. We demonstrated that MNV was aerosolized and that it remained infectious in the experimental setup used. Further studies required for understanding the behaviour of MNV in aerosols can thus be performed.
人诺如病毒主要通过粪-口途径传播，但也有报道称，诺如病毒病暴发是通过空气传播引起的，这是唯一的解释。我们使用鼠诺如病毒（MNV）作为人诺如病毒的替代物，以确定实验环境中传染性诺如病毒的气溶胶化。我们使用 3 升空气室系统对 MNV 进行气溶胶化。将病毒溶液（6 对数 TCID/ml）引入雾化器中以产生气溶胶，将没有盖子的 RAW 264.7 细胞培养皿放置在空气室内。在气溶胶暴露 30 或 90 分钟后，从培养皿中采集细胞培养液样本，并将培养皿置于 37°C、5%CO 的孵育箱中，用相差显微镜观察病毒细胞病变效应（CPE）。我们既确定了感染性 MNV TCID 滴度，也使用了 RT-qPCR 检测。在实验过程中，在雾化器中的 MNV 溶液中，病毒感染性在 30 和 90 分钟时保持稳定。在 30 分钟和 90 分钟暴露后，在 RAW 264.7 细胞培养皿介质中，空气室内的感染性 MNV TCID 值/ml 分别为 2.89±0.29 和 3.20±0.49 对数。MNV RNA 载量分别为 6.20±0.24 和 6.93±1.02 对数基因组拷贝/ml。随后，气溶胶暴露的 RAW 细胞培养皿中出现了典型的 MNV CPE。我们证明了 MNV 被气溶胶化，并且在使用的实验装置中保持感染性。因此，可以进行进一步的研究，以了解 MNV 在气溶胶中的行为。
