Developing Immunogens to Elicit Broadly Neutralizing anti-HIV-1 Antibodies

联合国艾滋病规划署每年记录了数百万新的HIV-1感染病例，因此HIV-1疫苗非常重要。 令人向往迄今为止，尽管进行了许多努力，但没有免疫方案可重复地产生广泛中和， 抗HIV-1抗体（bNAb）。最近可获得的天然样HIV-1包膜刺突（Env）三聚体引起了 中和自体2级病毒的抗体，但这些抗体仅具有有限的效力和广度。 bNAb的推断生殖系（iGL）抗体前体通常不结合HIV-1 Env的观察结果表明， 蛋白质或中和HIV-1的研究表明，合理设计的iGL靶向Env免疫原将被 需要启动bNAb反应。Bjorkman博士和Nussenzweig博士提出了一个高度合作的项目 将这种方法应用于两类HIV-1 bNAb的靶向表位：一类与PGT 121相关， V3可变环的碱基，并与N332 gp 120聚糖（V3/N332 bNAb）相互作用， bNAbs，一类新的CD 4模拟CD 4结合位点（CD 4 bs）来源于VH 1 -2生殖系基因的bNAbs 片段选择V3/N332和IOMA类别是因为（i）V3/N332 Ab是最有效的 的bNAbs，并普遍存在于艾滋病毒感染的个人谁开发bNAbs，（ii）IOMA的相对较低 大量的体细胞超突变及其正常长度的CDRL 3表明，它可能比CDRL更容易引起。 VRC 01类VH 1 -2衍生的CD 4 bs bNAb，严重体细胞突变并含有罕见的5-残基 CDRL 3，和（iii）免疫原设计将有利于天然糖基化Env的晶体结构 与V3/N332 bNAb 10-1074和IOMA结合的三聚体。Bjorkman实验室将创造免疫原， iGL和shepherd bNAb成熟，而Nussenzweig实验室开发免疫方案， bNAbs使用设计的免疫原。Nussenzweig实验室的具体目标是：（1）开发和简化 在iGL敲入小鼠中引发针对V3/N332的bNAb的免疫方案，（2）适应免疫方案 开发了用于在基因敲入小鼠中将V3/N332 bNAb转化为野生型和携带未重排 人抗体基因座，（3）开发免疫方案以引发IOMA样抗体，和（4）确定 未感染的人的幼稚B细胞库中IOMA和V3/N332 bNA B前体的频率 捐助者。Bjorkman实验室的具体目标是：（1）解决iGL-免疫原复合物的结构，以帮助 基于结构免疫原设计，（2）利用基于结构的设计和文库筛选鉴定Env 以高亲和力结合V3/N332 iGL的三聚体，（3）使用结构信息指导酵母的构建 展示文库以寻找结合IOMA iGL的罕见变体，（4）联合收割机结果以产生Env三聚体免疫原 结合两种bNAb的iGL，并与Nussenzweig博士一起评估双和单免疫原， 小鼠这些努力将得到核心A（自动化细胞/生化测定）和核心B（蛋白质 表达式）。拟议的实验将产生候选免疫原测试猕猴， 合作者马尔科姆·马丁博士和人类疫苗试验。

UNAIDS has documented millions of new HIV-1 infections every year, thus a vaccine for HIV-1 is highly desirable. To date, despite numerous efforts, no immunization regimen reproducibly elicits broadly neutralizing antibodies (bNAbs) against HIV-1. Recently available native-like HIV-1 envelope spike (Env) trimers elicit antibodies that neutralize autologous tier-2 viruses but these antibodies have only limited potency and breadth. The observations that inferred germline (iGL) antibody precursors of bNAbs do not generally bind HIV-1 Env proteins or neutralizing HIV-1 suggested that rationally designed iGL-targeting Env immunogens would be required to initiate bNAb responses. Drs. Bjorkman and Nussenzweig propose a highly collaborative project to apply this approach to target epitopes of two classes of HIV-1 bNAbs: a class related to PGT121 that binds to the base of the V3 variable loop and interacts with the N332gp120 glycan (V3/N332 bNAbs), and IOMA-like bNAbs, a new class of CD4-mimetic CD4 binding site (CD4bs) bNAbs derived from the VH1-2 germline gene segment. The V3/N332 and IOMA classes were chosen because (i) V3/N332 Abs are among the most potent of bNAbs and are commonly found in HIV-infected individuals who develop bNAbs, (ii) IOMA's relatively low number of somatic hypermutations and its normal-length CDRL3 suggest it may be more easily elicited than VRC01-class VH1-2–derived CD4bs bNAbs that are heavily somatically mutated and contain rare 5-residue CDRL3s, and (iii) immunogen design will be facilitated the crystal structure of a natively-glycosylated Env trimer bound to the V3/N332 bNAb 10-1074 and to IOMA. The Bjorkman lab will create immunogens to target iGLs and shepherd bNAb maturation, while the Nussenzweig lab develops immunization schemes to elicit bNAbs using the designed immunogens. The Nussenzweig lab specific aims are: (1) Develop and simplify immunization protocols that elicit bNAbs to V3/N332 in iGL knock-in mice, (2) Adapt immunization protocols developed for V3/N332 bNAbs in knock-in mice to wild type and AlivaMab mice that carry un-rearranged human antibody loci, (3) Develop an immunization protocol to elicit IOMA-like antibodies, and (4) Determine the frequency of IOMA and V3/N332 bNAb precursors in the naïve B cell repertoire of un-infected human donors. The Bjorkman lab specific aims are: (1) Solve structures of iGL–immunogen complexes to aid in structure-based immunogen design, (2) Use structure-based design and library screening to identify Env trimers that bind V3/N332 iGLs with high affinity, (3) Use structural information to guide construction of a yeast display library to find rare variants that bind IOMA iGL, (4) Combine results to create Env trimer immunogens that bind iGLs of both bNAbs and work with Dr. Nussenzweig to evaluate double and single immunogens in mice. These efforts will be supported by Core A (Automated cell/biochemical assays) and Core B (Protein Expression). The proposed experiments will produce candidate immunogens testing in macaques by collaborator Dr. Malcolm Martin and for vaccine trials in humans.