MVA-based vaccines against highly pathogenic avian influenza

描述(由申请人提供)：迫切需要一种高度安全和有效的疫苗，可以预防高致病性禽流感病毒(H5N1)。这种流感病毒株最近在东南亚出现，在家禽和野生动物物种中造成严重暴发，偶尔会影响人类，死亡率很高。这种病毒已经迅速在亚洲、欧洲和非洲蔓延，公众主要担心，进一步的重组可能会产生一种能够在人与人之间传播的病毒，从而可能引发下一次流感大流行。在一个相关的痘病毒载体中，我们已经证明了抗原表达水平/模式的重要性以及随后在产生保护性免疫反应中的作用。这项工作导致了新型重组痘病毒疫苗的开发，以防止鼠疫杆菌感染(1)。在这里，我们建议将这些发现改编并扩展到相关的痘病毒载体--改良的痘苗病毒安卡拉(MVA)。MVA作为构建重组流感疫苗的病毒疫苗载体具有明显的优势。在这个方案中，我们将1)通过MVA载体优化H5N1株的血凝素(HA)和核蛋白(NP)抗原的表达，2)评估启动子和抗原表达模式(例如细胞内、分泌和膜结合)对免疫反应的影响，3)确定这些重组病毒对致死攻击的保护作用。具体目标如下。1)利用MVA重组病毒构建和优化HA和NP抗原的表达。2)评价重组MVA/流感疫苗对小鼠致死性流感攻击的保护作用；3)评价重组MVA/流感疫苗在免疫缺陷小鼠中的安全性。将选择安全地为小鼠提供最全面的鼻腔流感保护的疫苗结构进行进一步分析。在随后的提案中，候选MVA/流感疫苗将在雪貂和/或非人类灵长类动物身上进行预防流感挑战的能力测试，并将为人类临床试验做准备。

DESCRIPTION (provided by applicant): There is an immediate need for a highly safe and efficacious vaccine that can protect against highly pathogenic avian influenza viruses (H5N1). This strain of influenza virus emerged recently in Southeastern Asia producing severe outbreaks in poultry and wildlife species and has occasionally affected humans with high mortality rates. The virus has quickly spread throughout Asia, Europe and Africa and there is a major public concern that further reassortment might create a virus capable of human- to human transmission that could produce the next flu pandemic. In a related poxvirus vector, we have demonstrated the importance of antigen expression levels/patterns and the subsequent effect in generating protective immune responses. This work resulted in the development of novel recombinant poxvirus vaccines that protect against Y. pestis infection (1). Here we propose to adapt and extend these findings to a related poxvirus vector, Modified vaccinia virus Ankara (MVA). MVA offers distinct advantages as a viral vaccine vector for the construction of recombinant influenza vaccines. In this proposal, we will 1) optimize hemmaglutinin (HA) and nucleoprotein (NP) antigen expression from the H5N1 strain by the MVA vector, 2) evaluate the effect that promoters and antigen expression patterns (e.g. intracellular, secreted, membrane-bound) might have on the immune response, and 3) determine the protection conferred by these recombinant viruses against lethal challenge. The specific aims are as follows. 1) Construct and optimize the expression of HA and NP antigens by MVA recombinant viruses. 2) Evaluate the efficacy of recombinant MVA/FLU vaccines for protection against lethal flu challenge in mice; and 3) Evaluate the safety of the recombinant MVA/FLU vaccines in immunodeficient mice. The vaccine construct that safely provides the most complete protection of mice from intranasal influenza challenge will be chosen for further analysis. In subsequent proposals, the candidate MVA/FLU vaccine will be tested in ferrets and/or non-human primates for the ability to protect against influenza challenge and will be prepared for human clinical trials.