Escape From Broadly Neutralizing MAbs by Genetically-Linked Early & Late HIV Envs

描述（由申请人提供）：最近有重要的发现，从慢性hiv感染者中分离出强效和广泛中和的单克隆抗体（bnMAb）。在这些发现的基础上，可能会尝试通过合理设计免疫原来重新引发这种抗体反应。尽管具有强大和广泛的中和活性，但用于产生这些bnmab的血清并没有在被分离的感染者中产生灭菌免疫，也没有中和所有被测试的1-2级病毒，这表明可能存在逃逸变异。因此，本建议的目标是表征这些广泛和有效的中和抗体的逃逸。主要目的是：(1)绘制一组原发性急性和慢性HIV分子克隆在对这些bnmab产生抗性的过程中使用的逃逸途径，(2)确定逃逸一种广泛中和抗体是否会由于HIV包膜糖蛋白（Env）结构的全局变化而改变对另一种广泛中和抗体的敏感性，以及(3)了解逃逸突变是否会改变所产生变体的适应性。为了实现这些目标，一个HIV克隆小组

DESCRIPTION (provided by applicant): Recently there have been important discoveries of potent and broadly neutralizing monoclonal antibodies (bnMAb) isolated from chronically HIV-infected individuals. It will likely follow that attempts will be made to re-elicit such antibody responses through the rational design of immunogens based on these discoveries. Despite having potent and broad neutralizing activity, the serum used to generate these bnMAbs did not however produce sterilizing immunity in the infected individuals from which they were isolated nor did they neutralize all of the Tier 1-2 viruses that were tested, suggesting potential escape variants. Therefore, the goal of this proposal is to characterize escape from these broad and potent neutralizing antibodies. The major aims are to (1) map the escape pathways used by a panel of primary acute and chronic HIV molecular clones in the development of resistance to these bnMAbs, (2) determine whether escape from one broadly neutralizing antibody changes the sensitivity to a different broadly neutralizing antibody due to global changes in the HIV envelope glycoprotein (Env) structure, and (3) understand whether the escape mutation(s) alter(s) the fitness of the resulting variant. To accomplish these aims, a panel of HIV clones that express early and late time-point Envs will be serially-passaged in the presence of bnMAbs (i.e. VRC01, VRC03, PG9 and PG16) to drive immunological escape. Then, sequential samples will be analyzed at each passage of the virus to chart the (i) accumulation of genetic mutations and (ii) development of resistance. Once escape mutants are generated and identified, neutralization assays with each escape mutant using the other bnMAbs will be performed. Moreover, escape mutant Envs will be subcloned into a replication-competent HIV background to determine whether the mutation(s) also affect the fitness of the virus. The information gained in this study is highly relevant to rational immunogen design, since it (i) deepens the understanding of the mechanisms used by primary Envs to escape from bnMAbs, (ii) may identify second-site and/or off-target mutations in Env that are involved in escape from bnMAbs, and (iii) may provide an estimate of the number of epitope targets that are needed to afford protective immunity against not only the transmitted founder virus, but also its possible escape variants. In the aggregate, this project is highly relevant to an understanding of the requirements for an effective vaccine that could prevent acquisition of HIV/AIDS.