A Novel HIV-1 Vaccine Targeting the 12 protease Cleavage Sites

描述(申请人提供)：开发一种有效的HIV-1预防性疫苗已被证明是一个巨大的挑战。到目前为止，经典的疫苗方法在处理感染免疫系统的关键组成部分的病毒方面失败了或产生了一定的效果，并显示出极大的抗原性多样性和快速变异。需要新的方法和想法来开发艾滋病毒-1的预防性疫苗。爱德华·詹纳根据挤奶女工身上观察到的自然免疫力研制出了成功的天花疫苗。因此，在高度暴露的未感染个体中记录的对HIV-1的自然免疫的相关性可能为开发针对HIV-1的预防性疫苗提供重要线索。从一组高度暴露的内罗毕女性性工作者中预防HIV-1感染的免疫学相关因素中，我们建议有效的HIV-1预防性疫苗应该针对HIV-1的关键部位，而针对HIV-1的12个蛋白酶裂解位点的疫苗可以防止HIV-1感染。HIV蛋白水解酶是一种由99个氨基酸组成的小分子天冬氨酸氨基转移酶，参与裂解Gag、Gag-Pol和Nef前体多聚蛋白。这一过程具有高度的特异性和时间规律性，对产生具有感染性的病毒颗粒至关重要。总共需要12个蛋白质分解反应才能产生具有感染性的病毒粒子。因此，一种对HIV-1的12个蛋白酶裂解位点产生免疫反应的疫苗将有几个主要优势。首先，宿主的免疫反应可能会在病毒在宿主中永久存在之前摧毁病毒。其次，疫苗可以迫使病毒积累突变，从而消除艾滋病毒蛋白水解酶的正常功能，从而消除传染性病毒粒子。第三，将免疫反应限制在这些部位可以避免分散免疫反应的注意力，因为免疫反应往往会产生不必要的炎症反应，过度的免疫激活，并吸引更多的艾滋病毒-1感染、建立和传播的目标。为了验证这一假设，我们将以毛里求斯食蟹猴和致病的SIVmac251为实验模型，以重叠SIVmac239的12个蛋白酶裂解位点的多肽为免疫原，与完整的GAG和完整的Env作为免疫原进行比较。我们将通过a)一个能够靶向树突状细胞并产生强大免疫反应的改良水泡性口炎病毒(VSV)载体系统来传递这些免疫原；b)一个纳米结构的粘膜传递系统。对感染的保护将通过猕猴抵抗反复低剂量阴道内致病性SIVmac251挑战的能力来检验。次要结果，如病毒载量设定点和CD4T细胞下降，也将进行比较。将进行病毒适合性分析，以验证集中的免疫反应可以驱动有害的病毒突变，并产生适合性和传播性减弱的病毒。这一假设和疫苗方法的证实将改变艾滋病毒疫苗开发的范式，并开发有效的预防性艾滋病毒疫苗。

DESCRIPTION (provided by applicant): Developing an effective preventative vaccine for HIV-1 has proved to be an enormous challenge. The classical vaccine approach has failed thus far or produced modest efficacy in dealing with a virus infects a key component of immune system and exhibits great antigenic diversity and mutates rapidly. Novel approaches and ideas are needed to develop a preventative vaccine to HIV-1. Edward Jenner developed the successful smallpox vaccine based on the natural immunity observed in milkmaids. Thus, the correlates of natural immunity to HIV-1 documented in highly exposed uninfected individuals may provide a vital clue for the development of a preventative vaccine to HIV-1. Learning from immunologic correlates of protection from HIV-1 infection in a group of highly exposed HIV resistant Nairobi female sex workers, we propose that an effective preventative vaccine to HIV-1 should target key sites of HIV-1 and a vaccine targeting the 12 protease cleavage sites of HIV-1 can prevent HIV-1 acquisition. HIV protease is a small 99-amino acid aspartic enzyme that mediates the cleavage of Gag, Gag-Pol and Nef precursor polyproteins. The process is highly specific, temporally regulated and essential for the production of infectious viral particles. A total of twelve proteolytic reactions are required to generate an infectious virion. Therefore, a vaccine generating immune responses to the 12 protease cleavage sites of HIV-1 would have several major advantages. First, the host immune response could destroy the virus before its permanent establishment in the host. Second, the vaccine could force the virus to accumulate mutations eliminating the normal function of the HIV protease thus eliminating infectious virions. Third, restricting the immune responses to these sites can avoid distracting immune responses that often generate unwanted inflammatory responses, excess immune activation, and attract more targets for HIV- 1 infection, establishment and spread. To test this hypothesis we will use Mauritian Cynomolgus macaques and pathogenic SIVmac251 as an experimental model and peptides overlapping the 12 protease cleavage sites of SIVmac239 as immunogens to compare with full Gag and full Env as immunogens. We will deliver these immunogens with a) a modified vesicular stomatitis virus (VSV) vector system capable of targeting dendritic cells and generating robust immune responses; b) a nanostructure mucosal delivery system. The protection from infection will be examined by the ability of the macaques to resist repeated low dose intravaginal pathogenic SIVmac251 challenges. Secondary outcome such as viral load set point and CD4+ T cell decline will also be compared. Viral fitness analysis will be conducted to validate that the focused immune responses can drive deleterious viral mutation and produce virus of attenuated fitness and transmissibility. Confirmation of this hypothesis and vaccine approach will shift the paradigm of HIV vaccine development and develop an effective preventative HIV vaccine.