Shimasaki Noriko, Nojima Yasuhiro, Sakakibara Masaya, Kikuno Ritsuko, Iizuka Chiori, Okaue Akira, Okuda Shunji, Shinohara Katsuaki
National Institute of Infectious Diseases.
Kitasato Research Center for Environmental Science.
Biocontrol Sci. 2018;23(1):7-15. doi: 10.4265/bio.23.7.
Recent studies have investigated the efficacy of air-cleaning products against pathogens in the air. A standard method to evaluate the reduction in airborne viruses caused by an air cleaner has been established using a safe bacteriophage instead of pathogenic viruses; the reduction in airborne viruses is determined by counting the number of viable airborne phages by culture, after operating the air cleaner. The reduction in the number of viable airborne phages could be because of "physical decrease" or "inactivation". Therefore, to understand the mechanism of reduction correctly, an analysis is required to distinguish between physical decrease and inactivation. The purpose of this study was to design an analysis to distinguish between the physical decrease and inactivation of viable phi-X174 phages in aerosols. We established a suitable polymerase chain reaction (PCR) system by selecting an appropriate primer-probe set for PCR and validating the sensitivity, linearity, and specificity of the primer-probe set to robustly quantify phi-X174-specific airborne particles. Using this quantitative PCR system and culture assay, we performed a behavior analysis of the phage aerosol in a small chamber (1 m) at different levels of humidity, as humidity is known to affect the number of viable airborne phages. The results revealed that the reduction in the number of viable airborne phages was caused not only by physical decrease but also by inactivation under particular levels of humidity. Our study could provide an advanced analysis to differentiate between the physical decrease and inactivation of viable airborne phages.
最近的研究调查了空气清洁产品对空气中病原体的功效。已建立一种标准方法，使用安全的噬菌体而非致病病毒来评估空气净化器对空气中病毒的减少效果；在运行空气净化器后，通过培养对空气中存活噬菌体进行计数来确定空气中病毒的减少情况。空气中存活噬菌体数量的减少可能是由于“物理减少”或“失活”。因此，为了正确理解减少机制，需要进行分析以区分物理减少和失活。本研究的目的是设计一种分析方法，以区分气溶胶中存活的φ-X174噬菌体的物理减少和失活。我们通过选择合适的PCR引物-探针组并验证其敏感性、线性和特异性，建立了一个合适的聚合酶链反应（PCR）系统，以可靠地定量φ-X174特异性空气传播颗粒。利用该定量PCR系统和培养测定法，我们在不同湿度水平的小室（1米）中对噬菌体气溶胶进行了行为分析，因为已知湿度会影响空气中存活噬菌体的数量。结果表明，空气中存活噬菌体数量的减少不仅是由于物理减少，还由于在特定湿度水平下的失活。我们的研究可以提供一种先进的分析方法，以区分空气中存活噬菌体的物理减少和失活。
