Prevention of airborne smallpox transmission

描述(由申请人提供)：仅靠疫苗开发可能不足以保护美国免受天花的生物恐怖袭击，特别是针对含有IL4基因的工程病毒。即使实施了组织严密的疫苗接种计划，主要的脆弱性仍然存在，包括对疫情的恐惧造成的大规模破坏，以及全国性天花疫苗接种计划的发病率和死亡率。因此，为了回应RRGP-BTRR关于“针对暴露风险人群的新预防策略”的请求，我们建议调查紫外线(254 Nm)杀菌照射(UVGI)作为防止主要天花病毒在医院和其他公共建筑中传播的策略的有效性。作为一项预防战略，空气卫生有几个重要的特点：它可以在疫情爆发前安全部署；它可以建立公众信心；它可以在查明疫情和开始接种疫苗运动之前的关键时期限制疫情的增长；它可以通过减少其他空气传播感染的传播，即使永远不会发生天花攻击，也可以对公众健康产生好处。在这个项目中，我们将使用由Acambis公司提供的一种低毒力痘苗病毒株作为主要天花的模拟物。最初的实验将在一个小型气雾室中进行，以验证采样和分析方法，并确定UVGI诱导的牛痘病毒指数衰减常数作为液滴核大小和相对湿度的函数。然后，我们将在医院房间大小的房间(4.5m x 3m x 2.9m)中模拟“真实世界”条件，以确定上层房间UVGI对消除痘病毒气溶胶的效用。气雾化病毒将被收集在液体旋流采样器和级联冲击器中，并进行培养以确定传染性。上层房间UVGI可能会降低房间下部的感染性微生物浓度，从而控制空气传播的感染在房间居住者中的传播，而不会使居住者暴露在大量的紫外线下。这项工作将为决定是否建议在医院和公共建筑中广泛实施上层房间UVGI作为预防天花和其他生物工程空气传播传染病的第一道防线提供可靠的科学依据。

DESCRIPTION (provided by applicant): Vaccine development alone may not be sufficient to protect the U.S. against bioterrorist attack with smallpox, especially against an engineered virus containing an IL4 gene. Major vulnerabilities remain, even with a well-organized vaccination program in place, including mass disruption caused by fear of an epidemic and the morbidity and mortality of a nationwide smallpox vaccination program. Therefore, in response to the RRGP-BTRR request for "new prevention strategies for those at risk of exposure," we propose to investigate the effectiveness of ultraviolet (254 nm) germicidal irradiation (UVGI) as a strategy for preventing dissemination of variola major virus in hospitals and other public buildings. As a prevention strategy air sanitation has several important attributes: it can be deployed safely before an outbreak; it can build public confidence; it can limit the growth of an outbreak during the critical period prior to identification of the outbreak and the start of a vaccination campaign; and it can have public health benefits even if an attack with smallpox never occurs by reducing spread of other airborne infections. In this project, we will use a low virulence vaccinia virus strain, provided by Acambis Corp., as a simulant for variola major. Initial experiments will be performed in a small aerosol chamber to validate sampling and analysis methods and to determine the UVGI induced exponential decay constants for vaccinia as a function of droplet nuclei size and relative humidity. Then, we will simulate "real world" conditions in a hospital room size chamber (4.5 m x 3 m x 2.9 m) to determine the utility of upper room UVGI for elimination of poxvirus aerosols. Aerosolized virus will be collected in a liquid swirling sampler and a cascade impactor and cultured to determine infectivity. Upper-room UVGI can potentially lower the concentration of infective organisms in the lower part of the room and thereby control the spread of airborne infections among room occupants, without exposing occupants to a significant amount of UV. This work will provide a sound scientific basis for decisions on whether to recommend wide spread implementation of upper room UVGI in hospitals and public buildings as a first line of defense against smallpox and other bioengineered airborne communicable infections.