Selecting HIV recombination libraries for stable Env trimer immunogens

描述（由申请人提供）：对付艾滋病毒/艾滋病全球流行病的一个较好的解决办法是有效的疫苗。HIV-1疫苗开发的一个主要重点是确定一种免疫原，该免疫原可以引发高滴度的中和抗体（nAb），以对抗循环初代病毒的包膜糖蛋白（Env）尖峰。病毒粒子和感染细胞表面的功能性（天然）Env是gp120-gp41异源三聚体。诱导HIV-1 nAb的一个关键障碍不是一般的诱导anti-Env Ab，而是反Env反应不成比例地诱导到不相关的Env及其亚基，而不是原生的Env三聚体。可能导致对HIV免疫原产生弱和/或分离特异性nAb反应的因素是Env中的序列变异性和异质性，以及膜表面三聚体的不稳定性和低拷贝数。

DESCRIPTION (provided by applicant): A preferable solution to the HIV/AIDS global pandemic is an effective vaccine. A major priority for HIV-1 vaccine development is to identify an immunogen that can elicit high titers of neutralizing antibody (nAb) against the envelope glycoprotein (Env) spikes on circulating primary viruses. The functional (native) form of Env on the surface of virions and infected cells is a gp120-gp41 heterotrimer. A critical barrier in eliciing HIV-1 nAb is not one of eliciting anti-Env Ab in general, but rather that anti-Env responses are disproportionately elicited to irrelevant forms of Env and its subunits, rather than to the native Env trimer. Factors that likely contribute to the elicitation of weak and/or isolate specific nAb responses to HIV immunogens are sequence variability and heterogeneity in Env, as well as lability and low copy number of the trimeric, native form that is found on membrane surfaces. The goal of this project is to identify, characterize and develop virus-like particles (VPs or VLPs immunogens that display Env trimers that are more stable, more homogeneously native and in higher copy number than that of wild-type HIV-1. From diverse Env libraries created using DNA recombination methods Env VPs will be subjected to a variety of destabilizing conditions and then selected for binding to trimer-specific nAbs and nAb precursors in native and receptor-activated conformations while counter-screening against non-neutralizing Abs. To identify VPs with improved yield and native Env trimer content, we will engineer and select from diverse gp41 cytoplasmic tail and Gag libraries, again using nAbs. We will immunize rabbits using selected VLPs with stable, high copy number Env trimers and determine serum nAb titers against related strains and heterologous isolates in HIV-1 neutralization assays. We will probe lead Env immunogens using serum Ab and a panel of mAbs in a variety of binding and neutralization assays to ascertain the extent of antigenic mimicry of wildtype Env trimers. Detailed molecular characterization of the stable Env trimers and antisera should allow further optimization of lead immunogens and immunization regimens to elicit crossreactive nAb responses against different primary isolates of HIV-1. We expect the proposed studies to positively contribute to the development of an Env trimer-based vaccine.