Becker Pablo D, Nörder Miriam, Weissmann Sebastian, Ljapoci Ronny, Erfle Volker, Drexler Ingo, Guzmán Carlos A
Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, D-38124 Braunschweig, Germany.
Institute of Virology, Technische Universität München, D-81675 Munich, Germany.
Vaccines (Basel). 2014 Jul 22;2(3):581-600. doi: 10.3390/vaccines2030581.
Viral vectors are promising tools for vaccination strategies and immunotherapies. However, CD8⁺ T cell responses against pathogen-derived epitopes are usually limited to dominant epitopes and antibody responses to recombinant encoded antigens (Ags) are mostly weak. We have previously demonstrated that the timing of viral Ag expression in infected professional Ag-presenting cells strongly shapes the epitope immunodominance hierarchy. T cells recognizing determinants derived from late viral proteins have a clear disadvantage to proliferate during secondary responses. In this work we evaluate the effect of overexpressing the recombinant Ag using the modified vaccinia virus early/late promoter H5 (mPH5). Although the Ag-expression from the natural promoter 7.5 (P7.5) and the mPH5 seemed similar, detailed analysis showed that mPH5 not only induces higher expression levels than P7.5 during early phase of infection, but also Ag turnover is enhanced. The strong overexpression during the early phase leads to broader CD8 T cell responses, while preserving the priming efficiency of stable Ags. Moreover, the increase in Ag-secretion favors the induction of strong antibody responses. Our findings provide the rationale to develop new strategies for fine-tuning the responses elicited by recombinant modified vaccinia virus Ankara by using selected promoters to improve the performance of this viral vector.
病毒载体是疫苗接种策略和免疫疗法中很有前景的工具。然而，针对病原体衍生表位的CD8⁺ T细胞反应通常仅限于显性表位，并且对重组编码抗原（Ag）的抗体反应大多较弱。我们之前已经证明，感染的专职抗原呈递细胞中病毒抗原表达的时间强烈影响表位免疫优势等级。识别源自晚期病毒蛋白的决定簇的T细胞在二次反应期间增殖明显处于劣势。在这项工作中，我们评估了使用改良痘苗病毒早期/晚期启动子H5（mPH5）过表达重组抗原的效果。尽管来自天然启动子7.5（P7.5）和mPH5的抗原表达看起来相似，但详细分析表明，mPH5不仅在感染早期诱导的表达水平高于P7.5，而且抗原周转也得到增强。早期的强烈过表达导致更广泛的CD8 T细胞反应，同时保持稳定抗原的启动效率。此外，抗原分泌的增加有利于诱导强烈的抗体反应。我们的研究结果为开发新策略提供了理论依据，即通过使用选定的启动子来微调重组改良安卡拉痘苗病毒引发的反应，以提高这种病毒载体的性能。
