Improved Genetically Modified H5N1 Influenza Vaccine

描述（由申请方提供）：禽流感病毒由于与流感大流行有关，对公共卫生构成重大威胁。1997年和2003- 2004年在亚洲爆发的高致病性H5 N1鸡流感的特征是感染个体的高死亡率。迄今为止，在人体中测试的所有候选疫苗的免疫原性都很差，这阻碍了有效的H5 N1疫苗的开发。虽然免疫原性差的机制尚不清楚，但据推测，人类中缺乏H5病毒的引发起主要作用。基因修饰的H5血凝素（HA）在其切割位点处具有毒性多元结构的耗竭，先前已显示为模拟野生型（wt）H5 N1病毒的抗原性的潜在疫苗候选物。然而，毒性结构逆转的可能性是非常令人担忧的。本项目的目的是通过基因工程提高H5疫苗的安全性和免疫原性。我们开发安全有效的H5疫苗的独特方法是基于使用含有H5流感病毒的B细胞表位和来自H3和H1亚型人流感病毒的T细胞表位的嵌合体。嵌合方法可能具有改善抗H5抗体应答的潜力，因为它含有已经在人群中引发的辅助性T细胞表位，因此可以促进中和抗体的产生。此外，嵌合方法还可以改善重组H5疫苗的安全性。I期研究旨在使用反向遗传学证明嵌合体的活力，并在小鼠中进行抗原性、生长特性和免疫原性分析。具体目的：1）构建并拯救人禽病毒嵌合体。2)在小鼠中评价安全性和免疫原性。

DESCRIPTION (provided by applicant): Avian influenza viruses pose a significant threat to public health due to their associations with influenza pandemics. The outbreaks of the highly pathogenic H5N1 chicken influenza in Asia in 1997 and 2003-4 are characterized by the high mortality among the infected individuals. Development of an effective H5N1 vaccine is hampered by the poor immunogenicity of all vaccine candidates tested in humans to date. Although the mechanism of the poor immunogenicity is unclear, lack of priming with H5 virus in humans has been speculated to play a major role. Genetically modified H5 hemagglutinin (HA) with depletion of the virulent polybasic structure at its cleavage site has previously been shown to be a potential vaccine candidate mimicking the antigenicity of the wild type (wt) H5N1 viruses. However, the possibility of reversion of the virulent structure is of great concern. The objective of this project is to improve the safety and immunogenicity of H5 vaccine through genetic engineering. Our unique approach for the development of a safe and effective H5 vaccine is based on using chimeras containing B-cell epitopes of H5 influenza virus and T-cell epitopes derived from H3 and H1 subtype human influenza viruses. The chimeric approach may have the potential of improving the anti-H5 antibody response, as it contains T-helper epitopes that are already primed in human population and therefore could facilitate the production of neutralizing antibodies. Furthermore, the chimeric approach may also improve the safety profile of recombinant H5 vaccine. The Phase I study is aimed to demonstrate the viability of the chimeras using reverse genetics, and to conduct analysis on antigenicity, growth property, and immunogenicity in mice. The Specific Aims are to: 1) construct and rescue the human-avian virus chimeras. 2) evaluate the safety and immunogenicity in mice.