HIV Envelope Peptide-Based Vaccine in SHIV-Rhesus Model

描述(由申请人提供)：人类免疫缺陷病毒1型(HIV-1)疫苗的开发工作受到以下因素的阻碍：病毒的高变异率，对保护性免疫的性质缺乏清楚的了解，以及可用于直接检测HIV抗原以进行保护的现有动物模型的局限性。我们测试了一种高度保守的HIV包膜多肽鸡尾酒疫苗在印度猕猴中的保护效果，方法是利用嵌合病毒Shiv，在这个模型中表达HIV包膜并导致艾滋病，从而允许基于包膜序列直接测试HIV疫苗。该疫苗鸡尾酒的HIV包膜多肽是通过在多个动物模型中进行的一系列研究以及对HIV感染的长期非进展者细胞的体外研究而选择的，用于在多种MHC单倍型的背景下进行广泛的交叉反应T细胞反应。由于多肽鸡尾酒疫苗在没有产生抗HIV抗体的情况下选择性地启动细胞免疫(CMI)，因此有可能在该模型中测试抗病毒TH和CTL反应的保护效果。使用总共30只猕猴进行了三项不同的疫苗研究，以交付含有弗氏佐剂和/或自体树突状细胞(DC)的多肽鸡尾酒疫苗。体外多肽冲击DC免疫的猕猴能有效地诱导CMI，而用SHV致病株(SHV[ku2]和SHV[89.6p])攻击后，大多数免疫动物的病毒设定点显著降低，并伴有血液中未检测到的病毒。重要的是，在接种疫苗的猴子中没有观察到反弹，一些猴子跟踪了三年多。这些结果有力地支持了HIV包膜多肽鸡尾酒的疫苗潜力和体外负载多肽的DC在启动保护性CMI反应方面的效率。我们推测，Fit3配体(FL)治疗后，在含有CpG的寡核苷酸(ODN)存在的情况下递送疫苗鸡尾酒将是在体内将疫苗靶向DC的有效策略。此外，我们建议，这一策略将使HIV包膜多肽鸡尾酒成为一种适用于人类的可行疫苗方法。我们在小鼠和灵长类动物的研究中获得了初步数据，支持FL介导的具有免疫原性的DC的多个亚群的动员。我们将测试在对猕猴进行FL处理后，在CpG-ODN中接种HIV包膜多肽鸡尾酒是否在启动强大的CMI和使用SIV[KU2]预防静脉攻击方面有效。由于HIV感染的主要途径是粘膜上皮，并且主要是由亲巨噬细胞的HIV毒株感染，我们还将在体内测试针对DC的多肽鸡尾酒的有效性，使用FL处理和CpG-ODN，然后使用Shiv[SF162P](表达亲巨噬细胞的HIV包膜)攻击黏膜。我们还将测试一种粘膜疫苗策略，使用一种新型突变霍乱毒素(CT2*)来提供多肽鸡尾酒，我们观察到这种毒素是一种强大的佐剂，可以在小鼠中启动对几种多肽抗原的系统和粘膜免疫反应，包括艾滋病毒疫苗多肽。

DESCRIPTION (provided by applicant): Vaccine development efforts against human immunodeficiency virus type 1 (HIV-1) are hindered by the high mutation rate of the virus, lack of clear understanding of the nature of the protective immunity, and limitations of available animal models for direct testing of HIV antigens for protection. We tested protective efficacy of a highly conserved HIV envelope peptide cocktail vaccine in Indian origin rhesus macaques by taking advantage of the chimeric virus SHIV, that expresses HIV envelope and causes AIDS in this model thereby allowing for direct testing of HIV vaccines based on envelope sequences. The HIV envelope peptides for the vaccine cocktail were selected through a series of studies in multiple animal models and in vitro studies with cells from HIV-infected long-term non-progressors, for broadly cross reactive T cell responses in the context of multiple MHC haplotypes. Since the peptide cocktail vaccine selectively primes cell-mediated immunity (CMI) in the absence of anti-HIV antibody production, it is possible to test protective efficacy of antiviral TH and CTL responses in this model. Three separate vaccine studies were conducted employing a total of 30 macaques for delivering the peptide cocktail vaccine with Freund's adjuvant and/or autologous dendritic cells (DC). Macaques immunized with ex vivo peptide cocktail-pulsed DC exhibited efficient induction of CMI, and upon challenge with pathogenic strains of SHIV (SHIV[ku2] and SHIV[89.6P]) showed significant reduction in viral set point accompanied by undetectable virus in the blood of majority of vaccinated animals. Importantly, no rebounds were observed in the vaccinated monkeys, some followed for over three years. These results strongly support the vaccine potential of the HIV envelope peptide cocktail and the efficiency of DC loaded ex vivo with peptides for priming protective CMI responses. We hypothesize that FIt3-ligand (FL) treatment followed by delivering the vaccine cocktail in the presence of CpG-containing oligodeoxynucleotides (ODN) will be an effective strategy for targeting the vaccine to DC in vivo. Further we propose that this strategy would entail the HIV envelope peptide cocktail to be a viable vaccine approach applicable to humans. We obtained preliminary data supporting FL-mediated mobilization of multiple subsets of DC with immunogenic properties in murine and primate studies. We will test whether FL treatment of macaques followed by vaccination with the HIV envelope peptide cocktail in CpG-ODN would be effective in priming strong CMI and protection against intravenous challenge using SHIV[KU2]. Since the major route of HIV infection is the mucosal epithelium and is predominantly by macrophage-tropic HIV strains, we will also test the effectiveness of the peptide cocktail targeted to DC in vivo using FL-treatment and CpG-ODN followed by mucosal challenge using SHIV[SF162P], (expressing macrophage-tropic HIV envelope). We will also test a mucosal vaccination strategy for delivering the peptide cocktail using a novel mutant cholera toxin (CT2*) that we observed to be a strong adjuvant for priming systemic and mucosal immune responses to several peptide antigens, including the HIV vaccine peptides in mice.