Broadly protective (universal) virus-like particle (VLP) based influenza vaccine

描述（由申请人提供）：我们建议开发一种广泛中和的、可能通用的流感疫苗，该疫苗基于展示重塑HA分子的病毒样颗粒（VLP），这些HA分子呈现隐藏的表位。这些重塑的HA将以缺乏显性高变表位的形式表达，而是显示出明显保守的亚显性抗原位点，已知其引发中和广谱流感病毒的抗体应答。当前流感疫苗的保护范围仅限于同源病毒或密切相关的变体，并且随着流感病毒的快速抗原进化，疫苗效力减弱。大多数保护性抗体靶向HA分子的球状头部上的高度可变和显性位点，尽管更保守和更少免疫识别的构象抗原位点也存在于HA的茎（HA2）中以及球状头部（HA1）和茎部分之间。已发现针对这些位点的分离的人抗体可中和广谱流感病毒。因此，似乎合理的是制备和测试显示这些高度保守的亚显性抗原位点的疫苗，并确定它们是否刺激在天然流感感染中或用含有完整HA分子的制剂接种后最小的广泛抗体应答。将重塑的HA分子掺入流感病毒样颗粒（VLP）中应该为开发广泛中和的疫苗提供极好的机会。VLP由四种结构性流感蛋白（M1、M2、HA和NA）共表达产生，不含病毒遗传物质，因此不能复制或引起感染。将产生展示不同重塑HA分子的VLP，通过用识别这些位点的特异性抗体进行免疫沉淀来表征和测试保守表位的存在。VLP免疫的小鼠血清的中和活性将通过使用三种抗原性不同的病毒的体外微量中和测定来评估。将在使用三种抗原性不同病毒的致死性攻毒研究中进一步研究单一或联合候选疫苗刺激的保护效力和免疫原性。最有希望的VLP的进一步发展将通过第二阶段SBIR提案进行。

DESCRIPTION (provided by applicant): We propose to develop a broadly neutralizing, possibly universal influenza vaccine based on virus-like particles (VLPs) displaying remodeled HA molecules which present otherwise cryptic epitopes. These remodeled HAs will be expressed in forms lacking the dominant hypervariable epitopes and instead display distinctly conserved subdominant antigenic sites known to elicit an antibody response that will neutralize a broad spectrum of influenza viruses. The protective scope of current influenza vaccines is restricted to homologous viruses or closely related variants and vaccine efficacy wanes following the fast antigenic evolution of the influenza virus. Most protective antibodies target highly variable and dominant sites on the globular head of the HA molecule, although more conserved and less immune-recognized conformational antigenic sites are also present in the stem (HA2) and between the globular head (HA1) and stem portions of HA. Isolated human antibodies directed toward these sites have been found to neutralize a broad spectrum of influenza viruses. It seems reasonable therefore to prepare and test vaccines that display these highly conserved subdominant antigenic sites and determine if they stimulate a broad antibody response which is minimal in a natural influenza infection or following vaccination with formulations containing whole HA molecules. Incorporation of remodeled HA molecules into influenza virus-like particles (VLPs) should provide an excellent opportunity to develop a broadly neutralizing vaccine. VLPs are generated by the co-expression of four structural influenza proteins (M1, M2, HA and NA) and do not contain viral genetic material and are therefore unable to replicate or cause infection. VLPs displaying different remodeled HA molecules will be produced, characterized and tested for the presence of conserved epitopes by immunoprecipitation with specific antibodies recognizing these sites. The neutralizing activity of VLP immunized mice sera will be assessed by an in-vitro micro- neutralization assay using three antigenically distinct viruses. The protective efficacy and immunogenicity stimulated by a single or combined candidate vaccine will be further investigated in lethal challenge studies with three antigenically diverse viruses. Further development of the most promising VLP(s) will be pursued by a phase II SBIR proposal.