Kulkarni Viraj, Valentin Antonio, Rosati Margherita, Rolland Morgane, Mullins James I, Pavlakis George N, Felber Barbara K
Human Retrovirus Pathogenesis Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, Maryland, United States of America.
Human Retrovirus Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, Maryland, United States of America.
PLoS One. 2014 Oct 22;9(10):e111085. doi: 10.1371/journal.pone.0111085. eCollection 2014.
To target immune responses towards invariable regions of the virus, we engineered DNA-based immunogens encoding conserved elements (CE) of HIV-1 p24gag. This conserved element vaccine is designed to avoid decoy epitopes by focusing responses to critical viral elements. We previously reported that vaccination of macaques with p24CE DNA induced robust cellular immune responses to CE that were not elicited upon wild type p55gag DNA vaccination. p24CE DNA priming followed by p55gag DNA boost provided a novel strategy to increase the magnitude and breadth of the cellular immune responses to HIV-1 Gag, including the induction of strong, multifunctional T-cell responses targeting epitopes within CE. Here, we examined the humoral responses induced upon p24CE DNA or p55gag DNA vaccination in macaques and found that although both vaccines induced robust p24gag binding antibody responses, the responses induced by p24CE DNA showed a unique broad range of linear epitope recognition. In contrast, antibodies elicited by p55gag DNA vaccine failed to recognize p24CE protein and did not recognize linear epitopes spanning the CE. Interestingly, boosting of p24CE DNA primed animals with p55gag DNA resulted in augmentation of antibodies able to recognize p24gag as well as the p24CE proteins, thereby inducing broadest immunity. Our results indicate that an effectively directed vaccine strategy that includes priming with the conserved element vaccine followed by boost with the complete immunogen induces broad cellular and humoral immunity focused on the conserved regions of the virus. This novel and effective strategy to broaden responses could be applied against other antigens of highly diverse pathogens.
为了使免疫反应靶向病毒的恒定区，我们构建了编码HIV-1 p24gag保守元件（CE）的基于DNA的免疫原。这种保守元件疫苗旨在通过将反应聚焦于关键病毒元件来避免诱饵表位。我们之前报道，用p24CE DNA对猕猴进行疫苗接种可诱导对CE产生强大的细胞免疫反应，而野生型p55gag DNA疫苗接种则不会引发这种反应。先用p24CE DNA启动，然后用p55gag DNA加强免疫，提供了一种新策略，可增强对HIV-1 Gag的细胞免疫反应的强度和广度，包括诱导针对CE内表位的强大多功能T细胞反应。在这里，我们检测了猕猴接种p24CE DNA或p55gag DNA疫苗后诱导的体液反应，发现虽然两种疫苗都诱导了强大的p24gag结合抗体反应，但p24CE DNA诱导的反应显示出独特的广泛线性表位识别。相比之下，p55gag DNA疫苗引发的抗体无法识别p24CE蛋白，也无法识别跨越CE的线性表位。有趣的是，用p55gag DNA对p24CE DNA启动免疫的动物进行加强免疫，导致能够识别p24gag以及p24CE蛋白的抗体增加，从而诱导最广泛的免疫。我们的结果表明，一种有效的定向疫苗策略，即先用保守元件疫苗启动，然后用完整免疫原加强免疫，可诱导聚焦于病毒保守区域的广泛细胞免疫和体液免疫。这种拓宽反应的新颖有效策略可应用于针对高度多样化病原体的其他抗原。
