McGuire Travis C, Leib Steven R, Mealey Robert H, Fraser Darrilyn G, Prieur David J
Department of Veterinary Microbiology and Pathology, Washington State University College of Veterinary Medicine, Pullman, WA 99164, USA.
J Immunol. 2003 Aug 15;171(4):1984-93. doi: 10.4049/jimmunol.171.4.1984.
Control of a naturally occurring lentivirus, equine infectious anemia virus (EIAV), occurs in most infected horses and involves MHC class I-restricted, virus-specific CTL. Two minimal 12-aa epitopes, Env-RW12 and Gag-GW12, were evaluated for presentation by target cells from horses with an equine lymphocyte Ag-A1 (ELA-A1) haplotype. Fifteen of 15 presented Env-RW12 to CTL, whereas 11 of 15 presented Gag-GW12. To determine whether these epitopes were presented by different molecules, MHC class I genes were identified in cDNA clones from Arabian horse A2152, which presented both epitopes. This horse was selected because it is heterozygous for the SCID trait and is used to breed heterozygous females. Offspring with SCID are used as recipients for CTL adoptive transfer, and normal offspring are used for CTL induction. Four classical and three putative nonclassical full-length MHC class I genes were found. Human 721.221 cells transduced with retroviral vectors expressing each gene had equine MHC class I on their surface. Following peptide pulsing, only cells expressing classical MHC class I molecule 7-6 presented Env-RW12 and Gag-GW12 to CTL. Unlabeled peptide inhibition of (125)I-labeled Env-RW12 binding to 7-6-transduced cells demonstrated that Env-RW12 affinity was 15-fold higher than Gag-GW12 affinity. Inhibition with truncated Env-RW12 demonstrated that amino acid positions 1 and 12 were necessary for binding, and single substitutions identified positions 2 and 3 as possible primary anchor residues. Since MHC class I 7-6 presented both epitopes, outbred horses with this allele can be immunized with these epitopes to optimize CTL responses and evaluate their effectiveness against lentiviral challenge.
对自然发生的慢病毒——马传染性贫血病毒（EIAV）的控制，在大多数受感染马匹中都会出现，且涉及主要组织相容性复合体（MHC）I类限制性、病毒特异性细胞毒性T淋巴细胞（CTL）。对两个最小的12个氨基酸的表位Env - RW12和Gag - GW12进行了评估，以确定具有马淋巴细胞抗原A1（ELA - A1）单倍型的马的靶细胞对其的呈递情况。15个靶细胞中有15个向CTL呈递了Env - RW12，而15个中有11个呈递了Gag - GW12。为了确定这些表位是否由不同分子呈递，在来自阿拉伯马A2152的cDNA克隆中鉴定了MHC I类基因，该马呈递了这两个表位。选择这匹马是因为它是严重联合免疫缺陷（SCID）性状的杂合子，用于繁育杂合子雌性。患有SCID的后代用作CTL过继转移的受体，正常后代用于CTL诱导。发现了四个经典的和三个推定的非经典全长MHC I类基因。用表达每个基因的逆转录病毒载体转导的人721.221细胞在其表面有马MHC I类分子。肽脉冲后，只有表达经典MHC I类分子7 - 6的细胞向CTL呈递Env - RW12和Gag - GW12。未标记肽对（125）I标记的Env - RW12与7 - 6转导细胞结合的抑制作用表明，Env - RW12的亲和力比Gag - GW12的亲和力高15倍。用截短的Env - RW12进行抑制表明，氨基酸位置1和12对于结合是必需的，单个取代确定位置2和3为可能的主要锚定残基。由于MHC I类分子7 - 6呈递了这两个表位，具有该等位基因的远交系马可用这些表位进行免疫，以优化CTL反应并评估它们对慢病毒攻击的有效性。
