Vaccine Modalities to Prevent HIV-I Infection

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。这项工作是与安万特-巴斯德公司的合作努力，后者与NCI有CRADA，并涉及与NIAID的机构内合作。目前正在对两种载体进行测试：一种是基于金丝雀痘的载体(ALVAC)，另一种是基因减毒的牛痘病毒株(哥本哈根株的衍生品)NYVAC。两种载体均能在早启动子或早启动子或晚启动子的控制下完成复制循环，表达外源基因。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，我们研究了一种假设，即传统的DNA质粒(针对表达进行了优化)可能会激发免疫反应，这些免疫反应可能会用携带相同SIV基因的重组痘病毒进一步放大增强作用。所获得的结果表明，确实，用DNA启动和用NYVAC-SIV增强至少能增强病毒特异性免疫反应10倍。因此，这种免疫方案对攻击性暴露后的病毒血症提供了更好的遏制。我们还在测试将所有辅助/调节基因添加到SIV/HIV结构基因的重要性。为此，我们构建了一种新的重组蛋白，该蛋白包含了活性部位缺失的rev、nef和tat的遗传信息。这种重组抗原将被用作疫苗成分。一旦实现了模式的最佳组合，通过研究免疫途径的重要性和免疫调节分子的帮助，可能会进一步优化其他免疫方案。第二部分：考虑到NYVAC-SIV-Gag-Poll-env疫苗候选疫苗在恒河猴身上获得的令人鼓舞的结果，我们推测这种疫苗在SIV感染后的免疫干预方案中也可能有效。因此，我们在猕猴身上建立了一个模型，用来测试在有或没有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可以增强SIV特异性的CD4+T辅助细胞和CD8+T细胞的细胞毒反应，以及疫苗接种是否增加了宿主在抗逆转录病毒治疗暂停后将病毒血症维持在低水平的能力。选择高度减毒的痘病毒NYVAC-SIV-Gag-Poll-env活重组疫苗候选疫苗作为疫苗方法来测试这些概念，因为它在猕猴身上证明了作为预防性疫苗候选疫苗的有效性。结果表明，建立一种动物模型是可行的，在该动物模型中，免疫和免疫干预可以以受控的方式进行评估，并且疫苗在接受HAART治疗的感染动物中都能激发/增强CD4+和CD8+T细胞反应。这一点在目前的担忧背景下非常重要，即HAART可能会沉默免疫反应，从而损害宿主。在病毒复制活跃的动物和接受HAART治疗的猕猴中，使用这种减毒活载体是安全的，这表明该方法可能用于人类。一项关于长期感染SIV251的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暂时的优势(Tryniszewska等人，《免疫学杂志》，2002年)。由于这些结果具有令人鼓舞的性质，2004年将使用基于NYVAC的艾滋病毒-1疫苗在艾滋病毒-1感染者中启动一项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等人，J Virol，2002。Stevceva等人，J Virol，2002。Stevceva等人，J Virol，2002。赫尔等，《免疫学杂志》，2002年。Tryniszewska等，《免疫学杂志》，2002年。赫尔等人，《DNA细胞生物学》，2002年。Fry等人，布拉德，2003。Franchini等人，《疫苗》，2002年。赫尔等人，病毒学，2002年。NACSA等人，病毒学，2003年。Radaelli等人，病毒学，2003。NACSA等人，《疫苗》，出版中。Moniuszko等人，J Virol，正在出版。Stevceva等人，病毒学，在印。Franchini等人，癌症研究进展，正在出版中。Edghill-Smith等，J Infect Dis，正在出版中。

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.