Establishing a universal model virus system for breath air aerosol studies, including an appropriate sampling system

正如在电话中已经指出的那样，严重缺乏关于携带病毒的呼吸空气气溶胶（BAA）的分散，老化和沉积的可靠数据。这一缺点的一个主要原因是该领域众多研究的可比性有限，这也是由于这些研究是用各种不同的粒子系统进行的。BAA的一些物理性质可以用聚苯乙烯乳胶粒模拟，也可以用噬菌体喷雾模拟。这些粒子系统仅适用于模拟释放后的粒子行为。人体呼吸道的释放过程是病毒在BAA颗粒内以各种（大小）级分和数量密度分布的原因，但无法获得。然而，释放条件不仅决定了颗粒的进一步命运，如干燥、老化、沉降，而且还决定了包封病毒的感染性。这些影响只能通过对患者（例如影响或COVID-19患者）的临床测试来评估，这意味着重大的健康风险以及对患者的健康负担相当大。本项目的目的是建立TT病毒作为非传染性的通用模型病毒系统，用于研究呼吸空气气溶胶中的病毒。TT病毒是以第一个被检测到的患者的姓名首字母命名的，是环节病毒科中的一种无包膜病毒。根据世界不同地区，10%至90%以上的成年人携带这种病毒，这种病毒被认为不会对健康造成任何负面影响。由于TT病毒也包含在呼吸道和BAA中，因此它可能是理想的模式生物。将通过我们实验室提供的各种采样和测量设备、呼吸空气采样室、口罩和头盔来研究不同BAA粒度级中TT病毒的存在。携带病毒的气溶胶采样的另一个挑战是采样效率低，特别是当要保持采样病毒的感染性时。因此，在对呼吸空气气溶胶中的TT病毒进行基本研究的同时，将建造一种新的采样装置，包括水冷凝室和撞击器，以高效地采样BAA中所含的病毒，同样重要的是，以保持感染性并可用于进一步测试的方式。

As stated already in the call, there is a significant lack of reliable data on dispersion, aging, and deposition of Breath Air Aerosol (BAA) carrying viruses. One main reason for this shortcoming is the limited comparability of the numerous studies in the field, which again is caused by the fact that these studies are carried out with a wide range of different particle systems. Some physical properties of BAA can be simulated by polystyrol latex particles, other by nebulizing bacteriophages. These particle systems are only suitable to simulate particle behavior after release. The release process by the human respiratory tract, which is responsible for the distribution of viruses in various (size) fractions and number densities inside BAA particles, is not accessible. However, the release conditions are responsible for the further fate of the particles, such as drying, aging, sedimentation, but also for the infectivity of the enclosed viruses. These effects can only be assessed by clinical tests with patients (e.g. influence or COVID-19 patients), implicating significant health risk as well as a considerable health burden for the patient.The aim of this project is to establish the TT-virus as non-infectious, universal model virus system for studies on viruses in Breath Air Aerosol. The TT virus, named after the initials of the first patient, where it was detected, is a genus of non-enveloped viruses in the family Anelloviridae. Depending on the world region, between 10 and more than 90% of all adults carry this virus, which is considered not to cause any negative health effects. As the TT virus is also contained in the respiratory tract and in BAA, it might be an ideal model organism. The presence of TT viruses in different BAA size fractions will be investigated by means of various sampling and measuring devices, breath air sampling chambers, masks, and helmets available in our labs. Another challenge in virus-carrying aerosol sampling is the low sampling efficiency, particularly when the infectivity of the sampled viruses is to be maintained. Hence, in parallel to the basic investigations on TT viruses on breath air aerosol, a novel sampling device, comprising a water condensation chamber and an impinger, will be constructed to sample viruses contained in BAA with high efficiency and, equally important, in a way that the infectivity is maintained and accessible for further tests.