CTL EPITOPES ON LASSA VIRUS

拉沙热病毒是沙粒病毒科的一员， 在撒哈拉以南的西非，发病率和死亡率都很高。拉沙 病毒在自然界中存在于其啮齿动物宿主，Mastomys natalensis， 在尿液中排出高滴度的病毒。男性感染通常 通过直接暴露于啮齿动物排泄物发生，尽管医院 感染也会发生，在许多情况下， 出口到非洲以外的国家。来自动物的可用证据 模型表明，从拉沙病毒感染中恢复取决于 主要是细胞免疫机制和中和抗体滴度 只有在疾病的恢复期才出现。为了获得 更好地了解这种疾病的特异性和机制， 保护性细胞介导的免疫应答，建议利用 最近开发的肽表位预测策略来预测 Lassa上识别的人MHC I类限制性T细胞表位 病毒糖蛋白和核衣壳蛋白基因，拉沙血清阳性 携带多个MHC I类等位基因的个体。表位将 基于预测承载必要条件的超基序的算法来预测 位置2和9锚残基和二级疏水口袋 HLA-A1、A2、A3、A11、A24、A33、B7和B44的残基，其在 总的来说，90%以上的黑人和高加索人都有代表性。 将合成含有预测基序和超基序的肽 通过多肽合成策略并测试结合活性 在类分子上。显示结合活性的肽将是 应用于靶细胞和CTL的细胞毒活性， 血清阳性个体将通过51 Cr释放试验进行评估， 阳性鉴定功能性CTL表位。预计这一 分析将提供人CTL特异性的清晰图像 针对拉沙病毒的活性，并有助于靶向保护 疫苗接种策略。

Lassa fever virus is a member of the Arenaviridae, which is responsible for substantial morbidity and mortality in sub-Saharan West Africa. Lassa virus persists in nature in its rodent host, Mastomys natalensis, which excretes high titers of virus in the urine. Infection of man usually occurs by direct exposure to rodent excretia, although nosocomial infections also occur, and on numerous occasions disease has been exported to countries outside of Africa. Available evidence from animal models suggest that recovery from Lassa virus infections is dependent primarily on cellular immune mechanisms, and neutralizing antibody titers only appear late in the convalescent stages of disease. In order to gain a better understanding of the specificity and mechanisms of this protective cell mediated immune response, it is proposed to utilize recently developed peptide epitope predictive strategies to predict the human MHC class l restricted T-cell epitopes recognized on the Lassa virus glycoprotein and nucleocapsid protein genes by Lassa seropositive individuals bearing multiple alleles of MHC class I. Epitopes will be predicted based on algorithms which predict supermotifs bearing requisite position 2 and 9 anchor residues and secondary hydrophobic pocket residues for HLA-A1, A2, A3, A11, A24, A33, B7 and B44, which in the aggregate are represented in more than 90% of blacks and caucasians. Peptides containing predicted motifs and supermotifs will be synthesized by multiple peptide synthesis strategy and tested for binding activity on class molecules. Peptides demonstrating binding activity will be applied to target cells and cytotoxic activity of CTL expanded from seropositive individuals will be assessed by 51Cr release assay to positively identify functional CTL epitopes. It is anticipated that this analysis will provide a clear picture of the specificity of human CTL activity directed against Lassa virus and aid in targeting protective vaccination strategies.