Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA.
J Immunol. 2010 Apr 15;184(8):4423-30. doi: 10.4049/jimmunol.0903955. Epub 2010 Mar 8.
The generation of a robust CD8(+) T cell response is an ongoing challenge for the development of DNA vaccines. One problem encountered with classical DNA plasmid immunization is that peptides produced are noncovalently and transiently associated with MHC class I molecules and thus may not durably stimulate CD8(+) T cell responses. To address this and enhance the expression and presentation of the antigenic peptide/MHC complexes, we generated single-chain trimers (SCTs) composed of a single polypeptide chain with a linear composition of antigenic peptide, beta(2)-microglobulin, and H chain connected by flexible linkers. In this study, we test whether the preassembled nature of the SCT makes them effective for eliciting protective CD8(+) T cell responses against pathogens. A DNA plasmid was constructed encoding an SCT incorporating the human MHC class I molecule HLA-A2 and the immunodominant peptide SVG9 derived from the envelope protein of West Nile virus (WNV). HLA-A2 transgenic mice vaccinated with the DNA encoding the SVG9/HLA-A2 SCT generated a robust epitope-specific CD8(+) T cell response and showed enhanced survival rate and lower viral burden in the brain after lethal WNV challenge. Inclusion of a CD4(+) Th cell epitope within the SCT did not increase the frequency of SVG9-specific CD8(+) T cells, but did enhance protection against WNV challenge. Overall, these findings demonstrate that the SCT platform can induce protective CD8(+) T cell responses against lethal virus infection and may be paired with immunogens that elicit robust neutralizing Ab responses to generate vaccines that optimally activate all facets of adaptive immunity.
生成强大的 CD8(+) T 细胞反应是 DNA 疫苗发展的一个持续挑战。在经典的 DNA 质粒免疫接种中遇到的一个问题是，产生的肽是非共价和瞬时与 MHC Ⅰ类分子结合的，因此可能不会持久地刺激 CD8(+) T 细胞反应。为了解决这个问题并增强抗原肽/MHC 复合物的表达和呈递，我们生成了由单个多肽链组成的单链三聚体 (SCT)，该多肽链具有抗原肽、β(2)-微球蛋白和 H 链的线性组成，通过柔性接头连接。在这项研究中，我们测试了 SCT 的预组装性质是否使它们能够有效地引发针对病原体的保护性 CD8(+) T 细胞反应。构建了一种 DNA 质粒，编码一种 SCT，该 SCT 包含人类 MHC Ⅰ类分子 HLA-A2 和来自西尼罗河病毒 (WNV) 包膜蛋白的免疫优势肽 SVG9。用编码 SVG9/HLA-A2 SCT 的 DNA 接种的 HLA-A2 转基因小鼠产生了强大的表位特异性 CD8(+) T 细胞反应，并在致命 WNV 攻击后显示出更高的存活率和更低的大脑病毒载量。在 SCT 中包含 CD4(+) Th 细胞表位不会增加 SVG9 特异性 CD8(+) T 细胞的频率，但确实增强了对 WNV 攻击的保护作用。总的来说，这些发现表明 SCT 平台可以诱导针对致命病毒感染的保护性 CD8(+) T 细胞反应，并且可以与引发强大中和 Ab 反应的免疫原配对，以生成最佳激活适应性免疫所有方面的疫苗。
