DNA Vaccines

该项目的一个重要目标仍然是产生用于特异性抗原的最大效率的表达载体。我们的假设是，DNA疫苗的剂量是次优的许多人的应用，因此，提高效率是必要的实用人类DNA疫苗。我们已经产生了一组优化的表达载体的HIV和SIV。HIV载体被开发用于最终的人类临床试验。在猕猴中研究了这些载体的免疫原性和保护免受猿猴/人类免疫缺陷病毒杂交病毒（SHIV）攻击的能力。与此同时，SIV表达载体在最可靠的人类AIDS模型系统中被开发和研究，即，SIV是一种与HIV密切相关的病毒，引起与人类艾滋病非常相似的病理学。我们的结果表明，在没有任何其他形式的疫苗加强的情况下，优化的DNA表达载体能够保护恒河猴在高致病性SIVmac 251攻击后免受高病毒血症。此外，我们还开发了强大的新DNA和蛋白质联合免疫方案，提高了免疫反应的幅度、速度和寿命。为了进一步提高疫苗效率，我们研究了不同候选抗原的内在特性。我们利用重组DNA技术操纵表达抗原形式的能力。我们已经表明，调节DNA产生的抗原的形式、稳定性和细胞命运对其免疫原性和产生的应答类型具有深远的影响。我们进行比较研究，以开发几种抗原的最佳形式。在恒河猴中的结果证实了表达抗原的形式影响免疫应答的类型和幅度。我们研究了几种不同的抗原形式，以实现最佳的免疫应答，并解决全球流行的HIV毒株的变异性。我们比较了由天然抗原、嵌合体、集中和共识候选物的混合物以及仅含有HIV蛋白的保守元件的抗原产生的免疫应答。这种比较可能导致保护性免疫应答的进一步优化。我们利用我们对基因调控的理解开发了非致病性SIV菌株，这些菌株在猕猴中保存了10年以上，但它们不会引起任何疾病。这些动物产生了强烈的保护性免疫应答，即使在用野生型SIV攻击后也能够抵抗高病毒血症和疾病发展。我们发现这些动物产生了针对难以中和的SIVmac 239的中和抗体，并且CD 8细胞有助于保护作用。我们还表明，这些动物产生高水平的细胞毒性CD 4细胞，这有助于病毒控制。这种猕猴模型对于进一步了解导致艾滋病的致病机制、不同组织中的病毒相互作用以及有助于防止疾病发展的免疫系统组成部分非常重要。

Summary An important goal of this project continues to be the generation of maximally efficient expression vectors for specific antigens. Our hypothesis is that the DNA vaccine dose is suboptimal for many human applications, therefore, increased efficiency is necessary for practical human DNA vaccines. We have generated a set of optimized expression vectors for HIV and SIV. HIV vectors are developed for eventual human clinical trials. These vectors are studied in macaques for immunogenicity and ability to protect against challenge with Simian/Human Immunodeficiency Virus hybrid viruses (SHIV). In parallel, SIV expression vectors are developed and studied in the most faithful model system for human AIDS, ie., challenge of Rhesus macaques by SIV, a virus closely related to HIV, which causes very similar pathology to human AIDS. Our results show that optimized DNA expression vectors in the absence of any other form of vaccine boosting are able to protect rhesus macaques from high viremia after challenge with a highly pathogenic SIVmac251 challenge. In addition, we have developed powerful new DNA and protein co-immunization protocols that increase the magnitude, rapidity and longevity of immune responses. To further improve vaccine efficiency we study the intrinsic properties of the different candidate antigens. We take advantage of the ability to manipulate the form of expressed antigen by recombinant DNA technology. We have shown that modulating the form, stability and cellular fate of the DNA-produced antigens has profound effects on their immunogenicity and the type of response generated. We perform comparative studies to develop optimal forms of several antigens. Results in rhesus macaques verified that the form of expressed antigen affects the type and magnitude of immune response. We study several different antigen forms to achieve optimal immune response and to address the variability of HIV strains circulating worldwide. We compare the immune response generated by either mixes of native antigens, mosaics, centralized and consensus candidates, and also antigens containing only conserved elements of HIV proteins. Such comparisons may lead to further optimization of a protective immune response. We have used our understanding of gene regulation to develop non-pathogenic strains of SIV, which are maintained in macaques for more than 10 years, yet they do not cause any disease. These animals develop a strong protective immune response and are able to resist high viremia and disease development even after challenge with wild-type SIV. We showed that these animals develop neutralizing antibodies against difficult-to-neutralize SIVmac239, and that CD8 cells contribute to the protective effect. We have also shown that these animals develop high levels of cytotoxic CD4 cells, which contribute to viral control. This macaque model is important for the further understanding of the pathogenic mechanisms leading to AIDS, the virus interactions in different tissues and the components of the immune system contributing to protection from disease development.