COMBINED APPROACH TO BROADLY PROTECTIVE AIDS VACCINES: PROJECT 4

这个子项目是利用资源的许多研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 子项目的主要研究者可能是由其他来源提供的， 包括其它NIH来源。 为子项目列出的总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 我们先前报道了不同“初免-加强”免疫方案的保护效力的比较研究，所述方案包括用表达HIV-1 SF 162 Env或SIVmac 239 Gag/Pol的重组牛痘或DNA载体初免，随后用DNA、蛋白质或表达相同抗原的异源病毒载体加强。结果显示，无论引发免疫原如何，用蛋白质疫苗加强的动物具有显著更高的抗体滴度，包括同源中和抗体（NtAb）。在SHIVSF 162 P4攻击后，在所有免疫组中观察到平均血浆病毒载量的显著降低。攻毒当天的NtAb滴度与攻毒后血浆病毒载量峰值之间存在负相关（斯皮尔曼r =-0.819，p <0.0001）。用蛋白质加强免疫的12只动物中有5只在攻击后显示高NtAb滴度和不可检测的病毒血症，与感染保护一致。我们还扩展了比较研究，包括蛋白质引发，然后用DNA、蛋白质或病毒载体加强。在用蛋白质疫苗进行两次免疫后，产生了高水平的病毒特异性抗体应答，包括同源NtAb。然而，用DNA或病毒载体进一步免疫显示很少或没有加强作用。直肠内SHIV 162 P4攻击后，蛋白质-DNA或蛋白质-蛋白质初免-加强免疫组中除一只动物外的所有动物均被感染。这些结果进一步支持了引发-加强免疫中的引发在产生针对灵长类慢病毒感染的保护性免疫中的重要作用。为了进一步确定这些动物中中和抗体应答的性质，将PBMC送至杜兰大学的James罗宾逊博士处，以分离抗HIV-1的中和单克隆抗体。来自罗宾逊博士的初步数据表明，这些抗体中的一些可能识别针对HIV-1包膜的构象依赖性表位。这些抗体的进一步表征正在进行中。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We previously reported comparative studies of the protective efficacy of different "prime-boost" immunization regimens consisted of priming with recombinant vaccinia or DNA vectors expressing HIV-1 SF162 Env or SIVmac239 Gag/Pol, followed by boosting with DNA, protein; or heterologous viral vector expressing the same antigens. Results showed that, regardless of the priming immunogen, animals boosted with protein vaccines had significantly higher antibody titers, including homologous neutralization antibodies (NtAb). After SHIVSF162P4 challenge, significant reduction of mean plasma viral load was observed in all immunization groups. An inverse correlation (Spearman's r = -0.819, p0.0001) was observed between NtAb titer on the day of challenge and peak plasma viral load after challenge. Five of 12 animals boosted with proteins showed high NtAb titer and no detectable viremia after challenge, consistent with protection from infection. We have also extended the comparative study to include protein priming, followed by boosting with DNA, protein or viral vector. After two immunizations with protein vaccines, high level of virus-specific antibody responses, including homologous NtAb, were generated. However, further immunizations with DNA or viral vectors showed little or no boosting effects. Following intrarectal SHIV162 P4 challenge, all but one animal in each of the protein-DNA or protein-protein prime-boost groups were infected. These results further support the important role of priming in the prime-boost immunization in the generation of protective immunity against primate lentivirus infection. To further define the nature of neutralizing antibody responses in these animals, PBMC were sent to Dr. James Robinson at Tulane University to isolate neutralizing monoclonal antibodies against HIV-1. Preliminary data from Dr. Robinson indicate that some of these antibodies may recognize conformation-dependent epitopes against HIV-1 envelope. Further characterization of these antibodies is in progress.