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Structural analysis of protective and non-protective T-cell epitopes encoded with in the retroviral gag gene product

逆转录病毒 gag 基因产物编码的保护性和非保护性 T 细胞表位的结构分析

基本信息

批准号：
13670305
负责人：
MIYAZAWA Masaaki
金额：
$ 0.51万
依托单位：
Kinki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

1) One of the mouse retroviral gag gene products, the N-terminal MA protein, contains multiple T-lymphocyte epitopes recognized by CD4-positive helper cells. One of these T-helper cell epitopes was mapped within amino acid residues 62 and 76, and another epitope was localized between residues 119 and 138 in the MA protein.2) CD4-positive T cells specifically reacting to the 62-76 epitope produced a large amount of IL-4, while T cells reactive to the epitope within 119-138 did not.3) To identify the antigenic structures that are required for protection against retroviral infection, various truncated forms of MA were expressed in a newly modified vaccinia virus vector, and mice were immunized with the resultant recombinant vaccinia viruses. All the truncated forms of MA lost the ability to protect mice, while the entire MA was effective. To elucidate if the truncation in the N-terminal portion affected the effectiveness of the whole MA due to the lack of the N-terminal residue required for protein myristylation, Gly at residue 2 was replaced with Ala in a mutant MA. This mutant MA localized in the cell nuclei, instead of cell membrane where myristylated proteins normally accumulate, and at the same time the vaccinia virus expressing this mutant MA lost its ability to protect mice against retroviral infection.4) Thus, myristylation of MA is necessary for its proper immunogenicity, and when myristylated, the Th2 epitope is not necessary, but an epitope in the C-terminal portion is required for protective efficacy of MA.

1)小鼠逆转录病毒gag基因产物之一，N-末端MA蛋白，含有多个由CD 4阳性辅助细胞识别的T淋巴细胞表位。这些T辅助细胞表位之一定位于氨基酸残基62和76内，另一个表位定位于MA蛋白中的残基119和138之间。2）与62-76表位特异性反应的CD 4阳性T细胞产生大量IL-4，而对119-138内的表位反应的T细胞则没有。3）为了鉴定保护免受逆转录病毒感染所需的抗原结构，在新修饰的牛痘病毒载体中表达各种截短形式的MA，并用所得重组牛痘病毒免疫小鼠。所有截短形式的MA都失去了保护小鼠的能力，而整个MA是有效的。为了阐明N-末端部分的截短是否由于缺乏蛋白肉豆蔻基化所需的N-末端残基而影响整个MA的有效性，在突变MA中用Ala替换残基2处的Gly。该突变MA定位于细胞核中，而不是肉豆蔻基化蛋白通常积累的细胞膜中，并且同时表达该突变MA的牛痘病毒丧失了其保护小鼠免受逆转录病毒感染的能力。4）因此，MA的肉豆蔻基化对于其适当的免疫原性是必需的，并且当肉豆蔻基化时，Th 2表位不是必需的，但C-末端部分的表位是MA的保护功效所必需的。