Recent studies on the role of T cells in Zika virus (ZIKV) infection have shown that T cell responses to Asian ZIKV infection are important for protection, and that previous dengue virus (DENV) exposure amplifies the protective T cell response to Asian ZIKV. Human T cell responses to African ZIKV infection, however, remain unexplored. Here, we utilized the modified anthrax toxin delivery system to develop a flavivirus enzyme-linked immunosorbent spot (ELISPOT) assay. Using human ZIKV and DENV samples from Senegal, West Africa, our results demonstrate specific and cross-reactive T cell responses to nonstructural protein 3 (NS3). Specifically, we found that T cell responses to NS3 protease are ZIKV and DENV specific, but responses to NS3 helicase are cross-reactive. Sequential sample analyses revealed immune responses sustained many years after infection. These results have important implications for African ZIKV/DENV vaccine development, as well as for potential flavivirus diagnostics based on T cell responses.

IMPORTANCE The recent Zika virus (ZIKV) epidemic in Latin America and the associated congenital microcephaly and Guillain-Barré syndrome have raised questions as to why we have not recognized these distinct clinical diseases in Africa. The human immunologic response to ZIKV and related flaviviruses in Africa represents a research gap that may shed light on the mechanisms contributing to protection. The goal of our study was to develop an inexpensive assay to detect and characterize the T cell response to African ZIKV and DENV. Our data show long-term specific and cross-reactive human immune responses against African ZIKV and DENV, suggesting the usefulness of a diagnostic based on the T cell response. Additionally, we show that prior flavivirus exposure influences the magnitude of the T cell response. The identification of immune responses to African ZIKV and DENV is of relevance to vaccine development.

T细胞在寨卡病毒（ZIKV）感染中的作用的最新研究表明，对亚洲ZIKV感染的T细胞反应对于保护很重要，以前的登革热病毒（DENV）暴露会放大对亚洲ZIKV的保护性T细胞反应。然而，人类对非洲ZIKV感染的T细胞反应尚待探索。在这里，我们利用改良的炭疽毒素传递系统开发了黄病毒酶联免疫吸附点（ELISPOT）测定法。使用来自西非塞内加尔的人类ZIKV和DENV样本，我们的结果证明了T细胞对非结构蛋白3（NS3）的特异性和交叉反应性。具体来说，我们发现T细胞对NS3蛋白酶的反应是ZIKV和DENV特异性的，但是对NS3解旋酶的反应是交叉反应的。顺序样本分析显示，感染后多年持续免疫应答。这些结果对非洲ZIKV / DENV疫苗的开发以及基于T细胞反应的潜在黄病毒诊断具有重要意义。

重要性最近在拉丁美洲流行的寨卡病毒（ZIKV）流行以及相关的先天性小头畸形和吉兰-巴雷综合征引起了人们对我们为什么没有在非洲认识到这些独特的临床疾病的疑问。非洲对ZIKV和相关黄病毒的人类免疫应答代表了一项研究空白，可能有助于阐明保护机制。我们研究的目的是开发一种廉价的检测方法，以检测和表征对非洲ZIKV和DENV的T细胞应答。我们的数据显示针对非洲ZIKV和DENV的长期特异性和交叉反应性人类免疫反应，表明基于T细胞反应的诊断方法的有用性。此外，我们表明先前的黄病毒暴露会影响T细胞反应的幅度。