Critical neutralizing domain-based vaccines against new SARS-like virus hCoV-EMC

描述(申请人提供)：一种新的人类冠状病毒，hCoV-EMC，最近在中东被发现。据报道，自2012年6月以来，该病毒引发了严重急性呼吸综合征(SARS)样疾病，已导致5人死亡，4人患病。由于hCoV-EMC在基因上与SARS-CoV有关，SARS-CoV是致命的SARS的病原体，在2003年爆发的8,098例感染病例中，有774人死亡，这引起了人们对这种致命疾病潜在的大流行传播的极大担忧。因此，迫切需要开发疫苗来预防hCoV-EMC感染的潜在暴发。我们先前已经证明，SARS-CoV刺突蛋白(S)S1亚基的受体结合结构域含有关键中和结构域，基于该受体结合结构域的亚单位疫苗能够在动物模型中诱导有效的中和抗体应答，并对SARS-CoV感染产生保护作用。通过对SARS-CoV和hCoV-EMC的S蛋白序列的比较分析，我们发现hCoV-EMC的S蛋白S1亚基也含有一个与SARS-CoV S蛋白中的RBD核心结构非常相似的区域。我们还发现，含有截短的hCoV-EMC S蛋白胞外区的重组蛋白与Fc融合，诱导了具有中和活性的S特异性抗体，表明hCoV-EMC S蛋白确实含有CND(S)。因此，我们假设可以从人冠状病毒-EMC S蛋白中鉴定出CND(S)，并在此基础上开发出一种有效的疫苗，该疫苗具有较强的中和抗体反应和对人冠状病毒-EMC感染的保护性免疫。本研究的具体目的是：1)从S蛋白及其亚基中鉴定出S的CND；2)设计基于CND的亚单位的hCoV-EMC疫苗；3)优化免疫方案；4)在动物模型中评价所选的候选hCoV-EMC疫苗对病毒攻击的体内保护作用。这项拟议研究的长期目标是开发一种有效和安全的基于CND的亚单位疫苗，以对抗新发现的可能导致未来人类暴发的SARS样病毒hCoV-EMC。

DESCRIPTION (provided by applicant): A novel human coronavirus, hCoV-EMC, was recently identified in the Middle East. It was reported to cause severe acute respiratory syndrome (SARS)-like disease, having killed 5 persons and sickened 4 others since June of 2012. Because hCoV-EMC is genetically related to SARS-CoV, the causative agent of the deadly SARS that killed 774 people among 8,098 infected cases during the 2003 outbreak, it has raised great concerns about the potential pandemic spread of this lethal disease. Therefore, developing vaccines to prevent the potential outbreak of hCoV-EMC infection is urgently needed. We have previously shown that the receptor-binding domain (RBD) of SARS-CoV spike (S) protein S1 subunit contains critical neutralizing domain (CND) and that the subunit vaccine based on the RBD/CND can induce potent neutralizing antibody responses and protection against SARS-CoV infection in animal models. By comparing and analyzing the S protein sequences of SARS-CoV and hCoV- EMC, we found that hCoV-EMC S protein S1 subunit also contains a region that exhibited a core structure very similar to that of RBD in SARS-CoV S protein. We also found that a recombinant protein containing the truncated ectodomain of hCoV-EMC S protein fused to Fc induced S-specific antibodies with neutralizing activity, suggesting that hCoV-EMC S protein does contain CND(s). We therefore hypothesize that CND(s) can be identified from the hCoV-EMC S protein, based which an effective vaccine with ability to elicit strong neutralizing antibody responses and protective immunity against hCoV-EMC infection can be developed. The specific aims of this proposal are to: 1) identify CND(s) from hCoV- EMC S protein and its subunits, 2) design CND-based subunit hCoV-EMC vaccines, 3) optimize immunization regimens for vaccination of animals with a selected hCoV-EMC vaccine candidate, and 4) evaluate the in vivo protective immunity of the selected hCoV-EMC vaccine candidate against viral challenge in an animal model. The long-term goal of the proposed study is to develop an effective and safe CND-based subunit vaccine against the newly identified SARS-like virus hCoV-EMC that may cause a future outbreak in humans.