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Abstract：
The mammarenavirus Lassa virus (LASV) causes the life-threatening hemorrhagic fever disease, Lassa fever. The lack of licensed medical countermeasures against LASV underscores the urgent need for the development of novel LASV vaccines, which has been hampered by the requirement for a biosafety level 4 facility to handle live LASV. Here, we investigated the efficacy of mRNA-lipid nanoparticle (mRNA-LNP)-based vaccines expressing the LASV glycoprotein precursor (LASgpc) or nucleoprotein (LCMnp) of the prototypic mammarenavirus, lymphocytic choriomeningitis virus (LCMV), in mice. Two doses of LASgpc- or LCMnp-mRNA-LNP administered intravenously (i.v.) protected C57BL/6 mice from a lethal challenge with a recombinant (r) LCMV expressing a modified LASgpc (rLCMV/LASgpc2m) inoculated intracranially. Intramuscular (i.m.) immunization with two doses of LASgpc- or LCMnp-mRNA-LNP significantly reduced the viral load in C57BL/6 mice inoculated i.v. with rLCMV/LASgpc2m. High levels of viremia and lethality were observed in CBA mice inoculated i.v. with rLCMV/LASgpc2m, which were abrogated by i.m. immunization with two doses of LASgpc-mRNA-LNP. The protective efficacy of two i.m. doses of LCMnp-mRNA-LNP was confirmed in a lethal hemorrhagic disease model of FVB mice i.v. inoculated with wild-type rLCMV. In all conditions tested, negligible and high levels of LASgpc- and LCMnp-specific antibodies were detected in mRNA-LNP-immunized mice, respectively, but robust LASgpc- and LCMnp-specific CD8+ T cell responses were induced. Accordingly, plasma from LASgpc-mRNA-LNP-immunized mice did not exhibit neutralizing activity. Our findings and surrogate mouse models of LASV infection, which can be studied at a reduced biocontainment level, provide a critical foundation for the rapid development of mRNA-LNP-based LASV vaccines.IMPORTANCELassa virus (LASV) is a highly pathogenic mammarenavirus responsible for several hundred thousand infections annually in West African countries, causing a high number of lethal Lassa fever (LF) cases. Despite its significant impact on human health, clinically approved, safe, and effective medical countermeasures against LF are not available. The requirement of a biosafety level 4 facility to handle live LASV has been one of the main obstacles to the research and development of LASV countermeasures. Here, we report that two doses of mRNA-lipid nanoparticle-based vaccines expressing the LASV glycoprotein precursor (LASgpc) or nucleoprotein (LCMnp) of lymphocytic choriomeningitis virus (LCMV), a mammarenavirus genetically closely related to LASV, conferred protection to recombinant LCMV-based surrogate mouse models of lethal LASV infection. Notably, robust LASgpc- and LCMnp-specific CD8+ T cell responses were detected in mRNA-LNP-immunized mice, whereas no virus-neutralizing activity was observed.
摘要：
哺乳动物拉沙病毒（LASV）导致危及生命的出血热疾病，拉萨热.缺乏针对LASV的许可医疗对策强调了开发新的LASV疫苗的迫切需要。这受到生物安全4级设施处理现场LASV的要求的阻碍。这里,我们研究了基于mRNA-脂质纳米颗粒（mRNA-LNP）的疫苗表达LASV糖蛋白前体（LASgpc）或原型哺乳动物病毒的核蛋白（LCMnp）的功效，淋巴细胞脉络膜脑膜炎病毒（LCMV），在老鼠身上。静脉内（i.v.）施用两个剂量的LASgpc-或LCMnp-mRNA-LNP，保护C57BL/6小鼠免受颅内接种的表达修饰的LASgpc（rLCMV/LASgpc2m）的重组（r）LCMV的致命攻击。用两种剂量的LASgpc-或LCMnp-mRNA-LNP进行的肌内（i.m.）免疫接种可显着降低静脉内接种rLCMV/LASgpc2m的C57BL/6小鼠的病毒载量。在静脉内接种rLCMV/LASgpc2m的CBA小鼠中观察到高水平的病毒血症和致死率，通过用两种剂量的LASgpc-mRNA-LNP进行i.m.免疫来消除。在静脉内接种野生型rLCMV的FVB小鼠的致死出血性疾病模型中证实了两个i.m.剂量的LCMnp-mRNA-LNP的保护功效。在所有测试条件下，在mRNA-LNP免疫的小鼠中检测到可忽略和高水平的LASgpc和LCMnp特异性抗体，分别,但诱导了强烈的LASgpc和LCMnp特异性CD8+T细胞反应。因此，来自LASgpc-mRNA-LNP免疫小鼠的血浆没有表现出中和活性。我们的发现和LASV感染的替代小鼠模型，可以在降低的生物防护水平下进行研究，为基于mRNA-LNP的LASV疫苗的快速开发提供了关键基础。IMPORTANCELassa病毒（LASV）是一种高致病性哺乳动物病毒，每年在西非国家造成数十万人感染。导致大量致命的拉沙热（LF）病例。尽管它对人类健康产生重大影响，临床批准,安全,并且没有有效的针对LF的医学对策。需要生物安全4级设施来处理实时LASV一直是LASV对策研究和开发的主要障碍之一。这里,我们报道了两种剂量的基于mRNA-脂质纳米颗粒的疫苗表达淋巴细胞脉络膜脑膜炎病毒（LCMV）的LASV糖蛋白前体（LASgpc）或核蛋白（LCMnp），一种与LASV基因密切相关的哺乳动物病毒，对基于重组LCMV的致死性LASV感染替代小鼠模型提供保护。值得注意的是,在mRNA-LNP免疫小鼠中检测到稳健的LASgpc和LCMnp特异性CD8+T细胞应答,而没有观察到病毒中和活性。
