Vaccine Modalities to Prevent HIV-I Infection

第1部分。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，Aventis-Pasteur与NCI有CRADA，并涉及与NIAID的机构内合作。目前正在测试两种载体：基于金丝雀痘的载体（ALVAC）和基因减毒牛痘株（哥本哈根株的衍生物）NYVAC。这两种载体都能在早期启动子或早/晚启动子的控制下完成其复制周期并表达异源基因。目前的假设是，由于这两种痘病毒载体，即使在没有完整的生命周期的情况下，仍然表达大量的它们的蛋白质，对异源抗原的反应可能是有限的。因此，我们研究了传统DNA质粒（优化表达）可能引发免疫反应的假设，这些免疫反应可能进一步放大携带相同SIV基因的重组痘病毒的增强作用。所获得的结果表明，确实，用DNA引物和用NYVAC-SIV增强可以使病毒特异性免疫反应增强至少10倍。因此，这种免疫方案可以更好地控制病毒暴露后的病毒血症。我们也在测试在SIV/HIV结构基因中添加所有辅助/调控基因的重要性。为此，我们构建了一种包含rev、nef和去除活性位点遗传信息的新型重组蛋白。该重组抗原将用作疫苗成分。一旦实现了最佳的方式组合，通过研究免疫途径的重要性和免疫调节分子的帮助，其他免疫方案可能会进一步优化。第2部分。鉴于在恒河猴中获得的令人鼓舞的结果，我们假设这种疫苗也可以有效地用于SIV感染后的免疫干预方案。因此，我们在猕猴中建立了一个模型，以此来测试在存在或不存在抗逆转录病毒治疗的情况下接种疫苗的效果。一项研究旨在评估接受抗逆转录病毒治疗的猕猴接种疫苗是否能增强siv特异性CD4+ t辅助细胞和CD8+ t细胞的细胞毒性反应，以及接种疫苗是否能增加宿主在停止抗逆转录病毒治疗后将病毒血症维持在低水平的能力。选择高度减毒痘病毒NYVAC-SIV-gag-pol-env活重组候选疫苗作为疫苗方法来测试这些概念，因为它在猕猴中被证明是一种有效的预防性候选疫苗。结果表明，建立一种动物模型的可行性，在这种模型中，免疫和免疫干预可以以受控的方式进行评估，并且在接受HAART治疗的感染动物中，疫苗可以激发/增强CD4+和CD8+ t细胞反应。这一点非常重要，因为目前人们担心HAART可能会抑制免疫反应，从而损害宿主。在病毒复制活跃的动物以及接受haart治疗的猕猴中使用这种减毒活载体是安全的，这表明该方法可用于人类。一项针对慢性SIV251感染猕猴接种疫苗效果的更大规模研究表明，接种疫苗可能会带来一些短暂的优势（Tryniszewska等人，J Immunol, 2002）。由于这些结果令人鼓舞，2004年将开始使用基于nyvac的HIV-1疫苗对HIV-1感染者进行安全性和免疫原性试验。最后，正在研究使用IL-7和IL-15等细胞因子作为疫苗的“全身佐剂”。参考文献：Pal et al., J Virol, 2002。中华微生物学杂志，2002。中华微生物学杂志，2002。helet al.，免疫学杂志，2002。Tryniszewska等人，免疫学杂志，2002。helet al.， DNA细胞生物学，2002。Fry et al., Blood, 2003。Franchini等人，疫苗，2002年。helet al.，病毒学，2002。Nacsa et al.，病毒学，2003。Radaelli et al.，病毒学，2003。Nacsa等人，疫苗，出版中。monuszko et al., J . Virol, in press。steve等人，病毒学，出版中。Franchini et al.，《癌症研究进展》，已出版。Edghill-Smith等人，《传染病杂志》，出版中。

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 have 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 potentiate the virus-specific immune response at least tenfold. Accordingly, this immunization regimen afforded better containment of viremia following challenge exposure. 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 have constructed a novel recombinant protein encompassing the genetic information of rev, nef, and tat devoided of active site. This recombinant antigen will be used as a vaccine component. Once an optimal combination of modalities is achieved, other regimens of immunization may be further optimized by investigating the importance of the route of immunization and the help of immunomodulatory molecules. 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 whereby 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 increased 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 to establish an animal model in which immunization and immune intervention could be assessed in a controlled fashion and that both CD4+ and CD8+ T-cell responses were 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 chronically SIV251 infected macaques has 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 the year 2004 using a NYVAC-based HIV-1 vaccine. Lastly, the use of cytokines such as IL-7 and IL-15 as "systemic adjuvants" of vaccines is being investigated. References: Pal et al., J Virol, 2002. Stevceva et al., J Virol, 2002. Stevceva et al., J Virol, 2002. Hel et al., J Immunol, 2002. Tryniszewska et al., J Immunol, 2002. Hel et al., DNA Cell Biol, 2002. Fry et al., Blood, 2003. Franchini et al., Vaccine, 2002. Hel et al., Virology, 2002. Nacsa et al., Virology, 2003. Radaelli et al., Virology, 2003. Nacsa et al., Vaccine, in press. Moniuszko et al., J Virol, in press. Stevceva et al., Virology, in press. Franchini et al., Advances in Cancer Research, in press. Edghill-Smith et al., J Infect Dis, in press.