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。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 我们曾报道过对不同的“初始-增强”免疫方案的保护效果的比较研究，包括用表达HIV-1 SF162 Env或SIVmac239Gag/Pol的重组疫苗或DNA载体启动，然后用DNA、蛋白质或表达相同抗原的异种病毒载体加强免疫。结果表明，无论是哪种免疫原，用蛋白疫苗加强免疫的动物具有显著更高的抗体效价，包括同源中和抗体(NtAb)。在SHIVSF162P4攻击后，所有免疫组的平均血浆病毒载量均显著降低。攻击当天NtAb滴度与攻击后血浆病毒载量峰值呈负相关(Spearman‘s r=-0.819，p0.0001)。在用蛋白质增强的12只动物中，有5只在攻击后表现出高NtAb效价和未检测到的病毒血症，这与对感染的保护一致。我们还扩大了比较研究的范围，包括蛋白质启动，然后用DNA、蛋白质或病毒载体增强。用蛋白质疫苗免疫两次后，产生了高水平的病毒特异性抗体反应，包括同源的NtAb。然而，进一步用DNA或病毒载体进行免疫几乎没有增强作用。在直肠内SHIV162 P4攻击后，蛋白-DNA或蛋白-蛋白质数增强组中除一只动物外，其余动物均被感染。这些结果进一步支持了启动免疫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的中和性抗体反应的性质，将PBMC送到杜兰大学的詹姆斯·罗宾逊博士那里，以分离抗HIV-1的中和性单抗。罗宾逊博士的初步数据表明，其中一些抗体可能识别HIV-1包膜的构象依赖表位。对这些抗体的进一步鉴定正在进行中。

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.