Evaluation of LASV Protective Immunity in Mice Using Reassortant Virus ML29

描述(由申请人提供)：拉萨病毒(LASV)是拉沙热(Lassa Fever，LF)的病原体，Lassa Fever是西非流行的一种人畜共患病的病毒性出血热，导致广泛传播的疾病和显著的发病率和死亡率。目前还没有针对LF的疫苗，而对这种疫苗的需求正在不断增加。利巴韦林是唯一已知的在感染后早期有效的治疗方法，在流行地区很难获得，而在广泛的流行地区控制啮齿动物水库是不可行的策略。此外，随着LASV被列为A类优先制剂，对疫苗开发研究的需求更高。然而，LASV是一种病原体，需要最高水平的生物遏制才能进行研究，因此开发疫苗既困难又昂贵。随着重组病毒ML29的产生，有可能开发一种小鼠模型，用于在生物安全级别4(BSL-4)环境之外评估候选LF疫苗。ML29是一种含有非致病性莫佩亚病毒(MOPV)复制机制的重组病毒，它编码LASV的主要抗原、糖蛋白前体(GPC)和核蛋白(NP)。与野生型LASV相比，它在体外和体内都表现出减弱的表型。此外，与过去使用伪型病毒呈现LASV抗原的努力不同，这种重组病毒是一种具有复制能力的完整病毒，表达野生型LASV免疫原GPC和NP，使ML29成为研究对抗LASV样攻击所涉及的免疫生物学的理想候选者。所建立的小鼠模型为脾细胞过继移植模型。近交系CBA/J小鼠已被证明对致死性脑内毒素(I.C.)敏感。用ML29挑战，但在腹膜腔内(Ip)没有表现出疾病。免疫，类似于密切相关的淋巴细胞性脉络膜脑膜炎病毒(LCMV)的原型。ML29免疫的小鼠被用来通过跟踪非特异性和特异性的细胞介导的免疫反应来进一步表征重组病毒引起的免疫反应。众所周知，抗体应答在病毒清除中的作用很小，而细胞对GPC和NP的应答似乎是对LCMV和LASV的主要保护手段。一旦建立，该模型将为研究LASV样免疫提供一个很好的工具，并为评估潜在的LF疫苗候选者提供一个适当的平台。ML29是一种介于莫佩亚病毒和拉萨病毒之间的重新组合病毒，它将使研究拉沙类阿雷纳病毒在小鼠身上引发的免疫反应成为可能。建议的小鼠模型将允许评估对拉沙样感染的免疫原性和评估拉沙热疫苗候选。

DESCRIPTION (provided by applicant): Lassa virus (LASV) is the causative agent of Lassa Fever (LF), a zoonotic viral hemorrhagic fever endemic in West Africa responsible for wide spread disease and significant morbidity and mortality. There currently exists no vaccine against LF, while the need for such a vaccine is ever increasing. Ribavirin, the only known treatment to be effective against LF early on after infection, is hard to come by in endemic areas while rodent reservoir control is an unfeasible strategy over the wide ranging areas of endemicity. Furthermore, with the classification of LASV as a Category A Priority agent the need for vaccine development research is even higher. However, LASV is a pathogen that requires the highest level of biocontainment for study and as such vaccine development is both difficult and costly. With the generation of a reassortant virus ML29 there exists the potential to develop a mouse model for the purpose of evaluating the LF vaccine candidates outside of a biosafety level 4 (BSL-4) environment. ML29 is a reassortant virus containing the replication machinery of the nonpathogenic Mopeia virus (MOPV), a genetic relative of LASV, and encodes the LASV major antigens, glycoprotein precursor (GPC) and the nucleoprotein (NP). It displays an attenuated phenotype both in vitro and in vivo as compared to wild type LASV. Furthermore, unlike past efforts to present LASV antigens using pseudotyped viruses, this reassortant virus is a replication competent complete arenavirus expressing wild type LASV immunogens GPC and NP making ML29 the ideal candidate to study the immunobiology involved in the protection against a LASV-like challenge. The proposed mouse model is a splenocyte adoptive transfer model. Inbred CBA/J mice have been shown to be susceptible to a lethal intracerebral (i.c.) challenge with ML29, but display no disease in response to an intraperitoneal (i.p.) immunization, similar to the closely related prototype arenavirus lymphocytic choriomeningitis virus (LCMV). ML29 immunized mice have been used to further characterize the immune response elicited by the reassortant virus by tracking non-specific and specific cell mediated immune responses. It is known that antibody responses play little role in viral clearance, while cell mediated responses to GPC and to NP seem to be the primary means of protection against LCMV and LASV. Once established, the model will provide an excellent tool for the study of a LASV-like immunity as well as an appropriate platform for the evaluation of potential LF vaccine candidates. ML29, a reassortant virus between Mopeia virus and Lassa virus will allow the study of the immune response elicited by a Lassa-like arenavirus in mice. The proposed mouse model will allow the evaluation of immunogenicity to a Lassa like-infection and the evaluation of Lassa fever vaccine candidates.