Recombinant CCR5 Inhibitors for Topical Microbicides

描述(由申请人提供)：这份R21/R33阶段性创新奖申请提议开发能够作为候选局部杀菌剂的能够重组表达的新型RANTES衍生物。这些分子针对的是负责初次传播的HIV-1分离株使用的CCR5共受体。使用相当于完全合成的PSC-RANTES的HIV-1分离物的两个具有抗CCR5活性的主要候选者已经使用一种创新的噬菌体展示选择过程被确定，该过程允许筛选数百万个CCR5结合分子。其中一个分子具有PSC-RANTES的抑制机制，CCR5内化和封存，并通过CCR5参与信号活性。第二个分子虽然在抑制病毒感染方面同样有效，但不会导致CCR5内化或通过CCR5传递信号。这些性质可以改善该分子的安全性。该提案的R21阶段的目标是确定这两个分子的活性机制、化合物去除后的活性持续时间以及对来自撒哈拉以南非洲的A、C和D主要传播株的活性。我们还将尝试在体外产生对这两种分子的抗药性变体，并比较这些分子在低pH值、高温和暴露于宫颈阴道灌洗液(CVL)时的稳定性。在这些实验中具有最佳性能组合的分子将被选择用于在R33阶段使用SHIV162P3阴道挑战模型对雌性恒河猴进行临床前评估。这些实验将确定预防传播的有效剂量，确定该剂量是否对延迟的病毒攻击具有保护作用，并评估局部炎症和促炎细胞因子的诱导作为安全性指标。从患有延迟性病毒血症的治疗动物中恢复的病毒将被评估对主要RANTES衍生物的抗药性。这些研究旨在产生一种安全、有效和廉价的蛋白CCR5抑制剂，用于在受全球艾滋病毒/艾滋病大流行影响最大的地区使用的局部杀菌剂。

DESCRIPTION (provided by applicant): This R21/R33 Phased Innovation Award application proposes to develop novel RANTES derivatives capable of recombinant expression as candidate topical microbicides. These molecules target the CCR5 coreceptor used by HIV-1 isolates responsible for primary transmission. Two lead candidates with antiviral activity against CCR5-using HIV-1 isolates equivalent to the fully synthetic PSC-RANTES have been identified using an innovative phage display selection process that allows screening of millions of CCR5 binding molecules. One of these molecules shares the inhibitory mechanism of PSC-RANTES, CCR5 internalization and sequestration, and also shares signaling activity via CCR5. The second molecule, although equally potent at inhibiting virus infection, does not cause CCR5 internalization or signaling via CCR5. These properties could improve the safety profile of this molecule. The objectives of the R21 phase of the proposal are to determine the mechanism of activity of the two molecules, the duration of activity after compound removal, and the activity against clade A, C, and D primary transmission isolates from sub- Saharan Africa. We will also attempt to generate resistant variants to both molecules in vitro, and compare the stability of the molecules to low pH, high temperature, and exposure to cervicovaginal lavage (CVL) fluid. The molecule with the best combination of properties in these experiments will be selected for preclinical evaluation in the R33 phase using the SHIV162P3 vaginal challenge model in female rhesus macaques. These experiments will establish the effective dose for preventing transmission, determine if that dose protects against delayed virus challenge, and evaluate local inflammation and induction of proinflammatory cytokines as indicators of safety. Virus recovered from treated animals with delayed viremia will be evaluated for development of resistance to the lead RANTES derivative. These studies are designed to lead to a safe, effective, and inexpensive protein CCR5 inhibitor for incorporation into a topical microbicide for use in areas most impacted by the global HIV/AIDS pandemic.