LPS模拟肽疫苗诱导保护性免疫应答的研究

发布时间：2018-05-17 02:15

本文选题：脂多糖 + 噬菌体随机肽库　；参考：《第一军医大学》2005年博士论文

【摘要】：脂多糖(lipopolysacchride,LPS)是引起多种感染性疾病的革兰氏阴性(G~-)菌重要的共同致病物质,可导致败血性休克等严重病理变化。鉴于G~-菌内毒素血症的高发病率和严重危害,针对LPS的治疗与预防的研究始终是人们极为关注的课题。目前尚无LPS或类脂A拮抗剂用于临床或进入临床观察;而在预防方面,预存抗LPS抗体与败血症的发生、大样本住院肿瘤患者、烧伤、外科手术等因感染死亡例数呈负相关的现象早已被证实,即对LPS诱发的病理进程有明确的保护作用,但这种保护力只限于对接种菌或特定血清型的LPS;而被动输入抗体则有时相限制,即感染前1小时内应用有效,这显然只适于动物实验。理想的LPS疫苗应能诱导再次免疫应答,所产生的抗体应是具广谱预防与保护作用。目前LPS疫苗研制所面临的主要困难包括:①LPS为TI-I(非胸腺依赖抗原-I)型抗原,自然诱导产生的抗体亲和力低、调理杀菌力弱,且无再次抗体应答,亦不能诱导特异性细胞免疫;②源于不同种属、不同株乃至不同血清型的LPS可具不同的抗原性,只能诱导产生与接种菌或LPS结合的抗体。因而至今尚无批准进入临床实验的具广谱保护作用的LPS疫苗。针对上述存在的问题,本课题的主要研究思路是:利用噬菌体肽库筛选获得的短肽模拟LPS的保守性结构表位,将其抗原表位的化学性质由脂多糖改变为短肽,由此使TI抗原改变为TD抗原,进而诱导机体内产生有效的再次抗体应答和交叉保护性免疫。本课题组在前期的工作中,从噬菌体肽库中筛选了数十个模拟位克隆,选择三个模拟鼠伤寒杆菌LPS表位的序列合成短肽,并证明用这三种模拟短肽免疫动物后,可诱发机体产生针对鼠伤寒杆菌LPS的抗体应答,但由于所获模拟位合成肽的免疫原性较弱,加之当时以BSA为载体,所产生的抗体效价较低,保护作用亦不明显。据此,本研究着重解决了具交叉保护性抗体的纯化,并以
[Abstract]:Lipopolysaccharide (LPSs) is an important common pathogenic substance of Gram-negative GPS-negative bacteria which causes many infectious diseases. It can cause severe pathological changes such as septic shock and so on. In view of the high incidence and serious harm of endotoxemia, the treatment and prevention of LPS has always been a subject of great concern. At present, no LPS or lipoid A antagonist has been used in clinic or in clinical observation. In prevention, there are pre-existing anti LPS antibodies and the occurrence of septicemia, large sample of cancer patients in hospital, burn, The negative correlation in the number of deaths due to infection, such as surgery, has long been confirmed, that is, it has a clear protective effect on the pathological process induced by LPS. However, the protective power is limited to inoculated bacteria or specific serotype LPSs, while passive injection of antibodies is sometimes limited, that is, it is effective within one hour before infection, which is obviously only suitable for animal experiments. The ideal LPS vaccine should be able to induce reimmune response and the antibody produced should have broad-spectrum preventive and protective effects. At present, the main difficulties in the development of LPS vaccine include TI-I (non-thymus dependent antigen-I-1) antigen, low affinity of naturally induced antibodies, weak bactericidal ability, no reantibody response and no specific cellular immunity. (2) LPS derived from different genera, strains or even serotypes had different antigenicity, and could only induce the production of antibodies bound to inoculation bacteria or LPS. So far, no broad spectrum protective LPS vaccine has been approved for clinical trials. In view of the above problems, the main ideas of this study are as follows: the short peptides obtained by phage peptide library are used to mimic the conserved structural epitopes of LPS, and the chemical properties of the epitopes are changed from lipopolysaccharide to short peptides. As a result, TI antigen was transformed into TD antigen, which induced effective reantibody response and cross-protective immunity. In our earlier work, we screened dozens of mimic clones from phage peptide library, selected three mimic LPS epitopes of S. typhimurium to synthesize short peptides, and proved that these three mimic peptides were used to immunize animals. It could induce antibody response against LPS of S. typhimurium, but the immunogenicity of the synthetic peptide was weak, and the antibody titer was low and the protective effect was not obvious. Therefore, this study focused on the purification of the cross-protective antibody, and the purification of the antibody with cross-protective antibody.
【学位授予单位】：第一军医大学
【学位级别】：博士
【学位授予年份】：2005
【分类号】：R392

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