Enhancing DNA vaccines using modified Cholera Toxin A1 Subunit as an adjuvant

描述（由申请方提供）：使用质粒DNA的疫苗接种有可能提供比常规疫苗更高的安全性和有效性，具有更高的稳定性，并加速产品开发。不幸的是，用DNA接种灵长类动物需要使用过大剂量的质粒进行多次接种。霍乱毒素（CTA 1）和相关的不耐热肠毒素（LTA 1）的A1结构域已被证明特别有希望作为佐剂，其可以增强DNA疫苗在小动物中的免疫原性，并且可以在灵长类动物中提供必要的剂量节省效应。然而，为了最大限度地利用这一前景，CTA 1或LTA 1在体内的活性应该得到改善。我们的目标是鉴定CTA 1或LTA 1的修饰，其将增强CTA 1或LTA 1的活性， 目的1：鉴定CTA 1或LTA 1活性位点中增强体外酶活性的突变;目的2：鉴定CTA 1或LTA 1与人ARF 6之间增强体外酶活性的融合构建体;以及目的3：鉴定来自目的1和2的构建体，其最佳地增强候选SIMmac 239-gag DNA疫苗的体内免疫原性。 将选择在体内显示至少10倍增强的佐剂性的候选构建体用于在拟在第2阶段中进行的灵长类动物研究中进行评价。第2阶段的成功候选疫苗将被纳入用于临床评价的候选HIV DNA疫苗。

DESCRIPTION (provided by applicant): Vaccination using plasmid DNA has the potential to provide enhanced safety and efficacy over conventional vaccines with increased stability, and accelerated product development. Unfortunately, vaccination of primates with DNA requires multiple inoculations using excessively large doses of plasmid. The A1 domains of cholera toxin (CTA1) and the related heat-labile enterotoxin (LTA1) have demonstrated particular promise as adjuvants that can enhance the immunogenicity of DNA vaccines in small animals and may provide a necessary dose sparing effect in primates. To maximally exploit this promise, however, the activity of CTA1 or LTA1 in vivo should be improved. Our objective is to identify modifications to CTA1 or LTA1 that will enhance their activity in vivo by pursuing the following aims: Aim 1: Identify mutations in the active site of either CTA1 or LTA1 that enhance enzymatic activity in vitro; Aim 2: Identify fusion constructs between CTA1 or LTA1 and human ARF6 that enhance enzymatic activity in vitro; and, Aim 3: Identify constructs from Aims 1, and 2 that optimally enhance the immunogenicity of a candidate SIMmac239-gag DNA vaccine in vivo. Candidate constructs that display a minimum of 10-fold enhanced adjuvanticity in vivo will be selected for evaluation in primate studies to be proposed in phase 2. Successful candidates in phase 2 will be incorporated into candidate HIV DNA vaccines intended for clinical evaluation.