Dose Optimization, Production & Tox Testing of Replicon-Vaccines for Smallpox

描述(由申请人提供)：拟议研究的目标是使用从委内瑞拉马脑炎(VEE)减毒株衍生的单周期、复制能力不强的甲型病毒复制子疫苗载体，优化安全有效的天花多抗原疫苗。初步研究已确定4个候选痘苗病毒(VACV)基因A33R、B5R、A27L和L1R(4pox)在动物体内表达时，可引起保护性免疫反应。在小鼠模型中，只要一次4Pox病毒样复制子颗粒(VRP)免疫，就能完全保护小鼠免受VACV(IHD-J株)的鼻腔攻击。这项建议的具体目的是(1)优化4POX疫苗单个VRP组分的免疫剂量，(2)大规模开发表达VACV基因的VRP疫苗的制造工艺，(3)制造适合临床评估的4POX VRP疫苗，以及(4)进行4POX VRP疫苗的毒理学测试。在经过认证的天花根除之后，世界上除两种天花病毒外的所有储存的天花病毒都被假定为销毁，导致了大多数天花疫苗接种计划的停止。因此，当今世界上的大多数人对天花几乎没有免疫力。由于一些原因，正痘病毒仍然是一个令人担忧的问题。自然发生的正痘病毒病和用作生物武器的正痘病毒的威胁只是两个例子。正痘病毒构成的大部分威胁可以通过接种疫苗来消除；然而，由于天花疫苗是一种活的正痘病毒，疫苗本身可能对具有免疫能力的人，特别是免疫受损的人构成严重的健康风险。在拟议研究的基础上，将通过临床前研究、试生产、临床材料生产和适合支持提交IND的毒理学测试来进行安全有效的替代天花疫苗(IND提交不在本提案的范围内)。

DESCRIPTION (provided by applicant): The objective of the proposed research is to optimize a safe and effective multi-antigen vaccine for smallpox using a single-cycle, replication-incompetent, alphavirus replicon vaccine vector that has been derived from attenuated strains of Venezuelan equine encephalitis (VEE). Preliminary studies have identified four candidate vaccinia virus (VACV) genes A33R, B5R, A27L and L1R (4pox) that when expressed in animals, elicit a protective immune response. Complete protection from intranasal challenge with VACV (strain IHD- J) could be demonstrated after as few as one 4pox virus-like replicon particle (VRP) immunization in a mouse model. The specific aims of this proposal are (1) to optimize the immunizing dose of individual VRP components of the 4pox vaccine, (2) to perform scale-up development of processes for manufacture of VRP vaccines expressing VACV genes, (3) to manufacture a 4pox VRP vaccine suitable for clinical evaluation, and (4) to perform toxicology tests of the 4pox VRP vaccine. The certified eradication of smallpox followed by the presumed destruction of all but two of the world's stocks of variola virus, led to the cessation of most smallpox vaccination programs. As a result, most of the world's population today has little or no immunity to smallpox. Orthopoxviruses remain a concern for a number of reasons. Naturally occurring orthopoxvirus disease and the threat of Orthopoxviruses used as biological weapons are just two examples. Much of the threat posed by Orthopoxviruses could be eliminated by vaccination; however, because the smallpox vaccine is a live orthopoxvirus the vaccine itself can pose serious health risks to immunocompetent individuals and especially to immunocompromised individuals. Based on the proposed studies, a safe and effective alternative smallpox vaccine will be carried through preclinical studies, pilot lot production, manufacture of clinical material and toxicology testing suitable to support submission of an IND (IND submission is not part of the scope of this proposal).