Viral Special Pathogens Branch, Division of High Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, Atlanta, GA, USA.
Viral Special Pathogens Branch, Division of High Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, Atlanta, GA, USA.
Antiviral Res. 2017 Oct;146:112-120. doi: 10.1016/j.antiviral.2017.08.014. Epub 2017 Aug 24.
Despite the serious public health impact of Crimean-Congo hemorrhagic fever (CCHF), the efficacy of antivirals targeting the causative agent, CCHF virus (CCHFV), remains debatable. Neutralizing monoclonal antibodies (MAbs) targeting the CCHFV glycoprotein Gc have been reported to protect mice against challenge with the prototype CCHFV strain, IbAr10200. However, due to extensive sequence diversity of CCHFV glycoproteins, it is unknown whether these MAbs neutralize other CCHFV strains. We initially used a CCHF virus-like particle (VLP) system to generate 11 VLP moieties, each possessing a glycoprotein from a genetically diverse CCHFV strain isolated in either Africa, Asia, the Middle East, or southeastern Europe. We used these VLPs in biosafety level 2 conditions to efficiently screen MAb cross-neutralization potency. Of the 16 MAbs tested, 3 (8A1, 11E7, and 30F7) demonstrated cross-neutralization activity with most CCHF VLPs, with 8A1 neutralizing all VLPs tested. Although binding studies suggest that none of the MAbs compete for the same epitope, combining 11E7, 30F7, or both 11E7 and 30F7 with 8A1 had no additive effect on increasing neutralization in this system. To confirm our findings from the VLP system, the 3 MAbs capable of strain cross-neutralization were confirmed to effectively neutralize 5 diverse CCHFV strains in vitro. Passaging CCHFV strains in the presence of sub-neutralizing concentrations of MAbs did not generate escape mutants resistant to subsequent neutralization. This study demonstrates the utility of the VLP system for screening neutralizing MAbs against multiple CCHFV strains, and provides the first evidence that a single MAb can effectively neutralize a number of diverse CCHFV strains in vitro, which may lead to development of future CCHF therapeutics.
尽管克里米亚-刚果出血热 (CCHF) 对公共卫生造成严重影响，但针对病原体 CCHF 病毒 (CCHFV) 的抗病毒药物的疗效仍存在争议。针对 CCHFV 糖蛋白 Gc 的中和单克隆抗体 (MAb) 已被报道可保护小鼠免受原型 CCHFV 株 IbAr10200 的攻击。然而，由于 CCHFV 糖蛋白广泛的序列多样性，尚不清楚这些 MAb 是否能中和其他 CCHFV 株。我们最初使用 CCHF 病毒样颗粒 (VLP) 系统生成了 11 种 VLP 片段，每种片段都含有一种来自非洲、亚洲、中东或东南欧分离的遗传上多样化的 CCHFV 株的糖蛋白。我们在生物安全 2 级条件下使用这些 VLP 来高效筛选 MAb 的交叉中和效力。在测试的 16 种 MAb 中，有 3 种（8A1、11E7 和 30F7）对大多数 CCHF VLP 表现出交叉中和活性，其中 8A1 中和了所有测试的 VLP。虽然结合研究表明，没有一种 MAb 竞争相同的表位，但将 11E7、30F7 或 11E7 和 30F7 与 8A1 结合使用并没有在该系统中增加中和作用的累加效应。为了确认我们在 VLP 系统中的发现，证实了 3 种能够进行株间中和的 MAb 能够有效地中和体外 5 种不同的 CCHFV 株。在亚中和浓度的 MAb 存在下传代 CCHFV 株不会产生对后续中和耐药的逃逸突变体。这项研究证明了 VLP 系统用于筛选针对多种 CCHFV 株的中和 MAb 的有效性，并首次提供了单一 MAb 可有效中和体外多种不同 CCHFV 株的证据，这可能为未来的 CCHF 治疗方法的发展提供依据。
