A novel live-attenuated Zika vaccine with a modified 5'UTR

总结 寨卡病毒（ZIKV）是一种蚊媒传播的黄病毒，已造成毁灭性的先天性寨卡综合征 (CZS)，包括2015 - 2016年人类新生儿的小头畸形，先天畸形和胎儿死亡 流行病此外，ZIKV感染可导致格林-巴利综合征（GBS）和脑膜脑炎。 成年人了目前，ZIKV的发病机制还不完全清楚，并且没有批准的治疗或治疗方法。 疫苗可用。尽管自2017年以来人类寨卡病例数量有所下降，但ZIKV病毒将可能成为 地方性流行病，并且仍然迫切需要一种可以预防CZS和成人寨卡疾病的疫苗， 未来的爆发。我们的研究小组最近通过以下方式开发了新的减毒活ZIKV毒株（命名为Z7）： 将50-RNA-核苷酸（nt）发夹插入流行前ZIKV的5'非翻译区（UTR）， 柬埔寨株，FSS 13025，其在神经毒力、免疫拮抗和蚊 与美国流行病分离株相比，我们的初步数据表明，Z7复制 在Vero细胞中产生高滴度，而不会引起明显的细胞病变效应（CPE）或丧失细胞毒性。 即使在连续传代10次后也能插入序列。有趣的是，我们在NS 2B中发现了一个突变S1417 A， Z7在第7次传代后仍能表达蛋白质，表明Z7可能通过传代适应了适应性突变。 重要的是，Z7诱导杀菌免疫，在高剂量攻击后完全防止病毒血症 美国流行株（PRVABC 59）在小鼠中的作用。这些结果表明，ZIKV 5 'UTR的修饰是不稳定的。 开发ZIKV和潜在的其他黄病毒的减毒活疫苗候选物的新策略。在 在本申请中，我们将首先在小鼠模型中表征Z7诱导的体液和细胞介导的免疫 （具体目标1），然后评价Z7在小鼠中的安全性特征（具体目标2）。在具体目标3中，我们 确定Z7衰减的作用机制。我们认为这个项目意义重大，因为 它将表征一种新型减毒活ZIKV疫苗候选物Z7的免疫性和安全性， 首次通过将发夹环引入病毒5' UTR开发。此外，该R15项目还将 为大学本科生和研究生提供宝贵而独特的培训机会 密西西比南部

Summary Zika virus (ZIKV) is a mosquito-transmitted flavivirus that has caused devastating congenital Zika syndromes (CZS), including microcephaly, congenital malformation, and fetal demise in human newborns in the 2015 - 2016 epidemics. In addition, ZIKV infection can cause Guillain-Barré syndrome (GBS) and meningoencephalitis in adults. Currently, ZIKV pathogenesis is incompletely understood, and there is no approved therapeutic or vaccine available. Although the number of human Zika cases has dropped since 2017, ZIKV will likely become endemic, and a vaccine that can prevent CZS and adult Zika diseases remains urgently needed to prepare for future outbreaks. Our research group recently developed a new live-attenuated ZIKV strain (named Z7) by inserting a 50-RNA-nucleotides (nt) hairpin into the 5’ untranslated region (UTR) of a pre-epidemic ZIKV Cambodian strain, FSS13025, which is attenuated in neurovirulence, immune antagonism, and mosquito infectivity compared with the American epidemic isolates. Our preliminary data demonstrate that Z7 replicates efficiently and produces high titers in Vero cells without causing apparent cytopathic effects (CPE) or losing the insert sequence even after ten consecutive passages. Interestingly, we identified a mutation S1417A in NS2B protein in Z7 after the 7th passage, indicating Z7 may have adapted a fitness mutation through the passaging. Importantly, Z7 induces sterilizing immunity that completely prevents viremia after a challenge with a high dose of an American epidemic strain (PRVABC59) in mice. These results suggest that modification of ZIKV 5’UTR is a novel strategy to develop live-attenuated vaccine candidates for ZIKV and potentially for other flaviviruses. In this application, we will first characterize Z7-induced humoral and cell-mediated immunity in a mouse model (Specific Aim 1), and then evaluate the safety features of Z7 in mice (Specific Aim 2). In Specific Aim 3, we will determine the mechanisms of action of Z7 attenuation. We believe that this project is highly significant because it will characterize the immunity and safety of a novel live-attenuated ZIKV vaccine candidate, Z7, which was developed for the first time by introducing a hairpin loop into a viral 5’ UTR. In addition, this R15 project will also provide a valuable and unique training opportunity to both undergraduate and graduate students at the University of Southern Mississippi.