Prevention of AIDS

为了研究艾滋病的预防，我们制备了高效的DNA表达载体，作为SIV和HIV的疫苗进行了评价。这项工作是基于我们之前的认识，即存在于HIV gag/pol和env编码区的RNA元件（称为INS）负责在没有Rev的情况下转录本的核保留和不稳定性，并且这些元件可以通过改变RNA组成而不影响氨基酸序列来消除。这些rna优化的gag和env表达载体在接种过疫苗的猕猴中介导保护性免疫反应的发展，无论是仅作为DNA还是作为DNA原疫苗方式。我们现在已经证明，在恒河猴/SIVmac251模型中，产生天然抗原和修饰抗原的DNA疫苗载体的组合能够诱导免疫反应，从而防止高病毒血症。引入的蛋白质修饰导致SIV抗原更有效的分泌，从而增加了接种恒河猴的细胞和体液免疫反应。我们的目标是使用不同的方法进一步改善DNA介导的免疫反应。我们与其他研究者合作，研究了SIV基因作为dna或作为病毒载体的一部分的免疫原性。我们已经证明这些DNA在DNA引物重组疱疹促进研究中提供了极好的引物，诱导保护性免疫反应。我们研究了细胞因子作为分子佐剂共同施用对进一步提高DNA疫苗接种效果的贡献。我们发现使用IL-12和IL-15质粒dna作为佐剂可大大提高小鼠和猕猴的免疫原性。另一个重要的新进展是，我们已经表明，通过体内电穿孔传递DNA可以大大改善细胞免疫反应，并且这些反应是持久的。因此，这些结果表明，基因传递和表达的改善显著提高了DNA疫苗的免疫原性和有效性。我们研究了抗逆转录病毒治疗（ART）期间DNA疫苗接种的效果。我们发现，接种siv感染的恒河猴疫苗可诱导有效的免疫反应，能够在抗逆转录病毒治疗中断后控制病毒血症。因此，DNA疫苗接种作为一种额外的治疗方式具有很大的潜力。我们发现DNA疫苗接种可以反复应用，从而进一步控制病毒血症。为了设计更好的疫苗策略，重要的是剖析保护性免疫的相关因素。“控制者”包括来自我们疫苗研究的动物，以及感染SIV减毒活株的动物，这些动物可以作为研究潜在机制的模型。这些动物使我们能够解剖导致疾病发展的细胞和病毒决定因素，它们也为研究导致保护性免疫的机制提供了独特的资源。这些研究将为具有不同致病结果的慢性逆转录病毒感染期间宿主免疫反应的建立和维持提供关键信息，并将有助于我们设计改进DNA疫苗接种研究。

To study prevention of AIDS, we have generated efficient DNA expression vectors, which are evaluated as vaccines against SIV and HIV. This work is based on our previous recognition that RNA elements (called INS) present within the gag/pol and env coding regions of HIV are responsible for nuclear retention and instability of the transcripts in the absence of Rev, and that these elements can be eliminated by changing the RNA composition without affecting the amino acid sequence. These RNA-optimized gag and env expression vectors mediate the development of protective immune responses in vaccinated macaques when used as DNA only as well as DNA prime vaccine modality. We have now shown that that a combination of DNA vaccine vectors producing native and modified antigens are able to induce immune responses able to protect from high viremia in the rhesus macaque/SIVmac251 model. The introduced modifications of the proteins led to more efficient secretion of the SIV antigens resulting in increased cellular and humoral immune responses in the vaccinated rhesus macaque. Our goal has been to further improve DNA mediated immune responses using different approaches. In collaboration with other investigators, we have studied immunogenicity of SIV genes either as DNAs or as part of viral vectors. We have shown that these DNAs provide an excellent prime in DNA prime-recombinant Herpes boost studies inducing protective immune responses. We investigated the contribution of cytokines co-administered as molecular adjuvant to further improve the efficacy of DNA vaccination. We found that the use IL-12 and IL-15 plasmid DNAs as adjuvants resulted in greatly improved immunogenicity in mice and macaques. Another important new development is that we have shown that DNA delivery via in vivo electroporation elicits greatly improved cellular immune responses and these responses are long-lasting. Thus, these results indicate that improved gene delivery and expression dramatically improves immunogenicity and effectiveness of DNA vaccination. We have investigated the effect of DNA vaccination during antiretroviral treatment (ART). We have found that vaccination of SIV-infected rhesus macaques induces potent immune responses that are able to control viremia after ART interruption. Thus, DNA vaccination has great potential to be used as an additional therapeutic modality. We have found that DNA vaccination can be applied repeatedly leading to further control of viremia. To design better vaccine strategies, it is important to dissect correlates of protective immunity. Among the 'controllers' are animals from our vaccine studies as well as animals infected with live-attenuated SIV strains serve as model to study the underlying mechanisms. Such animals allow us to dissect the cellular and viral determinants that contribute to disease development and they also provide a unique resources to study mechanisms leading to protective immunity. These studies will provide critical information about the establishment and maintenance of host immune responses during chronic retroviral infections with distinct pathogenic outcomes and will aid in our design to improve DNA vaccination studies.