Combination of Vaccine Modalities to Prevent HIV-I Infec

部分1.研究计划的第一部分是在恒河猴模型中评估高度减毒的重组痘病毒候选疫苗。这项工作是与Aventis Pasteur的合作努力，Aventis Pasteur与NCI有一个CRADA，并涉及与NIAID的机构内合作。正在测试两种载体：基于金丝雀痘的载体（ALVAC）和遗传减毒牛痘菌株（哥本哈根菌株的衍生物）NYVAC。两种载体都能够完成其复制周期，并在早期或早期/晚期启动子的控制下表达异源基因。工作假设是，因为这两种痘病毒载体，即使在没有完整的生命周期的情况下，仍然表达大量的蛋白质，对异源抗原的反应可能是有限的。因此，我们研究了这样的假设，即常规DNA质粒（针对表达进行了优化）可以引发免疫应答，所述免疫应答可以进一步用携带相同SIV基因的重组痘病毒扩增加强。所获得的结果表明，实际上，用DNA引发并用NYVAC-SIV加强使病毒特异性免疫应答增强至少十倍（Hel等人，J Immunol 2001）。因此，该免疫方案在攻击暴露后提供了更好的病毒血症遏制（Hel et al.，J Immunol 2002）。我们还在测试将所有辅助/调节基因添加到SIV/HIV结构基因中的重要性。为此目的，我们构建了一种新的重组蛋白，其包含rev、nef和达特的遗传信息，不含活性位点（Hel等人，Vaccine 2002）。这种重组抗原已被用作疫苗组分，最近未发表的数据表明多价疫苗（即，具有更多抗原的那些）提供更好的保护。一旦实现了最佳的模式组合，可以通过研究免疫途径的重要性和免疫调节分子的帮助来进一步优化其他免疫方案。最近，我们发现中枢记忆CD 8 + T细胞应答似乎比效应记忆CD 8 + T细胞应答更重要，因为前者而不是后者与病毒复制的遏制相关（Vaccari et al.，未公布的数据）。因此，我们正在研究改善中央记忆反应的策略。部分2.鉴于在恒河猴中用预防性NYVAC-SIV-gag-pol-env候选疫苗获得的令人鼓舞的结果，我们假设这样的疫苗在SIV感染后的免疫干预方案中也是有效的。因此，我们在猕猴中开发了一种模型来测试在存在或不存在抗逆转录病毒治疗的情况下疫苗接种的效果。一项研究旨在评估接种抗逆转录病毒治疗的猕猴是否可以增强SIV特异性CD 4 + T辅助细胞和CD 8 + T细胞的细胞毒性反应，以及接种疫苗是否可以增加宿主在抗逆转录病毒治疗暂停后维持低水平病毒血症的能力。选择高度减毒的痘病毒NYVAC-SIV-gag-pol-env活重组疫苗候选物作为疫苗方法来测试这些概念，因为其在猕猴中作为预防性疫苗候选物的有效性已得到证实。结果证明了建立动物模型的可行性，其中可以以受控的方式评估免疫和免疫干预，并且在用HAART治疗的感染动物中通过疫苗引发/加强CD 4+和CD 8 + T细胞应答。这一点是非常重要的背景下，目前的关注，HAART可能沉默免疫反应，损害主机。这种减毒活载体的使用在具有活跃病毒复制的动物中以及在HAART处理的猕猴中是安全的，这表明该方法可用于人类。在慢性感染SIVmac 251的猕猴中进行的关于疫苗接种功效的更大研究表明，疫苗接种可赋予一些暂时优势（Tryniszewska et al.，J Immunol 2002）。由于这些结果令人鼓舞，未来几年将使用基于NYVAC的HIV-1疫苗在HIV-1感染者中进行安全性和免疫原性试验。最后，正在研究使用细胞因子如IL 7和IL 15作为疫苗的“全身佐剂”。参考文献：Nacsa等人，Virology 2003; Fry等人，Blood 2003; Franchini Clinical and Applied Immunology Reviews 2003; Little等人，Blood 2003; Belyakov等人，PNAS 2003; Radaelli等人，Virology 2003; Edghill-Smith等人，J Infect Dis 2003; Moniuszko等人，J Virol 2003;Franchini等人，Vande Woude和Klein：Advances in Cancer Research 2003; Nacsa et al. Vaccine 2004; Stevceva et al. Virology 2004; Franchini et al. Expert Rev Vaccines 2004; Moniuszko et al. J Virol 2004.货货车Rompay et al. J AIDS in press; Edghill-Smith et al. J Infect Dis in press.

Part 1. The first part of the research plan is to assess highly attenuated recombinant poxvirus vaccine candidates in the rhesus macaque model. This work is a collaborative effort with Aventis Pasteur, which has a CRADA with the NCI, and involves intra-agency collaboration with the NIAID. Two vectors are being tested: a canarypox-based vector (ALVAC) and the genetically attenuated vaccinia strain (a derivative of the Copenhagen strain) NYVAC. Both vectors are able to complete their replication cycle and express heterologous genes under the control of early or early/late promoters. The working hypothesis is that, because both poxvirus vectors, even in the absence of a complete life cycle, still express a large number of their proteins, the response against the heterologous antigens may be limited. Thus we investigated the hypothesis that conventional DNA plasmid (optimized for expression) may prime immune responses that may further amplify boosting with recombinant poxviruses carrying the same SIV genes. The results obtained indicate that, indeed, priming with DNA and boosting with NYVAC-SIV potentiates the virus-specific immune response at least tenfold (Hel et al., J Immunol 2001). Accordingly, this immunization regimen afforded better containment of viremia following challenge exposure (Hel et al., J Immunol 2002). We are also testing the importance of the addition of all the accessory/regulatory genes to the SIV/HIV structural genes. For this purpose we constructed a novel recombinant protein encompassing the genetic information of rev, nef, and tat devoided of active sites (Hel et al., Vaccine 2002). This recombinant antigen has been used as a vaccine component and recent unpublished data demonstrate that polyvalent vaccines (i.e., those with more antigens) provide better protection. Once an optimal combination of modalities is achieved, other immunization regimens may be further optimized by investigating the importance of the route of immunization and the help of immunomodulatory molecules. Recently, we uncovered that central memory CD8+ T cell responses appear to be more important than effector memory CD8+ T cell responses as the former but not the latter correlated with containment of viral replication (Vaccari et al., unpublished data). Thus, we are investigating strategies to improve central memory responses. Part 2. In view of the encouraging results obtained with a preventive NYVAC-SIV-gag-pol-env vaccine candidate in rhesus macaques, we hypothesized that such a vaccine could also be effective in a regimen of immune intervention following SIV infection. Thus, we develop a model in macaques to test the effect of vaccination in the presence or absence of antiretroviral therapy. A study was designed to assess whether vaccination of macaques treated with antiretroviral therapy could enhance SIV-specific CD4+ T-helper and CD8+ T-cell cytotoxic responses and whether vaccination could increase the ability of the host to maintain viremia at low levels following antiretroviral therapy suspension. The highly attenuated poxvirus NYVAC-SIV-gag-pol-env live recombinant vaccine candidate was chosen as a vaccine approach to test these concepts because of its demonstrated effectiveness as a preventive vaccine candidate in macaques. The results demonstrate the feasibility of establishing an animal model in which immunization and immune intervention could be assessed in a controlled fashion and both CD4+ and CD8+ T-cell responses elicited/boosted by a vaccine in infected animals treated with HAART. This point is very important in the context of the present concern that HAART may silence the immune response to the detriment of the host. The use of this attenuated live vector is safe in animals with active viral replication as well as in HAART-treated macaques, suggesting that the approach may be used in humans. A larger study on efficacy of vaccination in macaques chronically infected with SIVmac251 suggested that vaccination may confer some transient advantage (Tryniszewska et al., J Immunol 2002). Because of the encouraging nature of these results, a safety and immunogenicity trial in HIV-1-infected individuals will be initiated in coming years using a NYVAC-based HIV-1 vaccine. Lastly, the use of cytokines such as IL7 and IL15 as "systemic adjuvants" of vaccines is being investigated. References: Nacsa et al. Virology 2003; Fry et al. Blood 2003; Franchini Clinical and Applied Immunology Reviews 2003; Little et al. Blood 2003; Belyakov et al. PNAS 2003; Radaelli et al. Virology 2003; Edghill-Smith et al. J Infect Dis 2003; Moniuszko et al. J Virol 2003;Franchini et al. in Vande Woude and Klein: Advances in Cancer Research 2003; Nacsa et al. Vaccine 2004; Stevceva et al. Virology 2004; Franchini et al. Expert Rev Vaccines 2004; Moniuszko et al. J Virol 2004. Van Rompay et al. J AIDS in press; Edghill-Smith et al. J Infect Dis in press.