本文關(guān)鍵詞：惡性瘧原蟲次黃嘌呤—鳥嘌呤—黃嘌呤磷酸核糖轉(zhuǎn)移酶細胞免疫保護作用的研究　出處：《第二軍醫(yī)大學》2006年碩士論文　論文類型：學位論文

  更多相關(guān)文章： 次黃嘌呤-鳥嘌呤-黃嘌呤-磷酸核糖轉(zhuǎn)移酶 HGXPRT 細胞免疫 T淋巴細胞系

【摘要】：瘧疾目前仍然是嚴重威脅人類健康的寄生蟲病,由于瘧原蟲抗藥性以及蚊媒抗殺蟲劑的產(chǎn)生和擴散,使瘧疾防治面臨嚴重困難。因此,研制有效的瘧疾疫苗已成為瘧疾防治重要潛在的替代途徑。 研制瘧疾紅內(nèi)期疫苗對降低瘧疾的發(fā)病率和死亡率具有重要作用。針對紅內(nèi)期原蟲免疫保護機制的研究,早期工作主要集中在體液免疫的作用。事實上紅內(nèi)期原蟲確能誘導產(chǎn)生保護性抗體,這類抗體在體外能完全抑制瘧原蟲生長,許多動物試驗結(jié)果也表明抗體在清除紅內(nèi)期原蟲感染中發(fā)揮重要作用。由于紅細胞表面缺乏MHC分子,因此細胞毒性T淋巴細胞(CTL)對紅內(nèi)期原蟲不能發(fā)揮效應作用。但實驗表明,在B細胞缺陷的小鼠模型中進行免疫攻擊感染試驗,結(jié)果顯示免疫小鼠能產(chǎn)生對瘧原蟲攻擊感染的免疫保護效力。盡管這種免疫力不能完全清除攻擊感染的瘧原蟲,但可控制原蟲密度在很低水平。顯然,該免疫保護效力是由細胞免疫介導的。此外,CD4~+T細胞過繼免疫小鼠也能對瘧原蟲攻擊感染產(chǎn)生保護作用。這些結(jié)果表明在瘧原蟲的紅內(nèi)期免疫機制中,體液免疫和CD4~+T細胞介導的細胞免疫均發(fā)揮重要的作用。 近年來,許多紅內(nèi)期疫苗候選抗原陸續(xù)得到鑒定,但這些抗原中絕大多數(shù)是針對保護性體液免疫的抗原。最近Makobongo等將所有紅內(nèi)期原蟲抗原進行組分化并建立各組分的CD4~+T細胞品系,通過過繼免疫和攻擊感染試驗確定了具有保護保護作用的T細胞品系,并初步鑒定瘧原蟲次黃嘌呤-鳥嘌呤-黃嘌呤-磷酸核糖轉(zhuǎn)移酶(hypoxanthine guanine xanthine phosphoribosyl transferase,HGXPRT)為這種保護性CD4~+T細胞的靶抗原。HGXPRT是嘌呤核苷酸補救合成途徑中的一個酶,可催化5-磷酸核糖焦磷酸(PRPP)與嘌呤反應生成嘌呤核苷酸。在哺乳動物體內(nèi),除有補救合成途徑外,還有嘌呤核苷酸從頭合成途徑,但在瘧原蟲僅有補救合成途徑,只能利用補救途徑合成生命所必需的核苷酸,故而HGXPRT對于瘧原蟲便顯得尤為重要,成為廣泛關(guān)注的抗瘧疾藥物的靶標。因此有必要制備重組蛋白建立特異T細胞品系,以進一步確定其細胞免疫的免疫保護作用,并在此基礎(chǔ)上鑒定其保護性T細胞表位。 本實驗室利用畢氏酵母系統(tǒng)表達并純化了惡性瘧原蟲HGXPRT重組蛋白,
[Abstract]:Malaria is still a serious parasitic disease threatening human health. Malaria control is facing serious difficulties due to the resistance of malaria parasites and the emergence and spread of mosquito vectors. Therefore, the development of effective malaria vaccine has become an important potential alternative way for malaria control.
The development of malaria erythrocytic stage vaccine plays an important role in reducing malaria morbidity and mortality. The research on protective immunity mechanism of blood stage, early work focused on the role of humoral immunity. In fact erythrocytic protozoa can induce protective antibodies, the antibody can completely inhibit parasite growth in vitro and many animal experiments also showed that antibodies play an important role in eliminating parasite of blood stage. Due to the lack of red blood cell surface MHC molecules, so the cytotoxic T lymphocyte (CTL) of erythrocytic protozoa can not play effect. But the experiment showed that the immune attack experimental infection in a mouse model of B cell defects in the results show, immunized mice can produce immune protection effect on Plasmodium infection. Although this attack cannot completely eliminate infection immunity to Plasmodium, but can control the density of protozoa In a very low level. Obviously, is mediated by cell immunity the protective immunity. In addition, CD4~+T cell adoptive immunized mice can produce protective effects on parasite infection attacks. These results suggest that the immune mechanism in the Plasmodium falciparum erythrocytic stage, cell immunity Humoral immunity and CD4~+T cell mediated both play an important role.
In recent years, many erythrocytic stage vaccine candidate antigens have been identified, but most of these antigens is the protective humoral immune antigen. Recently Makobongo all erythrocytic protozoa antigen and establish CD4~+T cell differentiation group strain components, T cell lines with the protective effect is determined by the adoptive immune attack and infection test, and preliminary identification of Plasmodium hypoxanthine guanine xanthine phosphoribosyltransferase (hypoxanthine guanine xanthine phosphoribosyl transferase, HGXPRT) as the target antigen of.HGXPRT in the protective CD4~+T cell is an enzyme of purine salvage synthesis pathway, catalyzes the 5- phosphoribosyl pyrophosphate (PRPP) and the reaction of purine purine nucleotides. In mammals, in addition to a salvage pathway, and de novo purine nucleotide synthesis pathway, but in Plasmodium Only the salvage pathway, can only use the nucleotide salvage pathway for the synthesis of life, so it is very important to HGXPRT for Plasmodium, become a widespread concern of anti malaria drug targets. So it is necessary for the preparation of recombinant proteins to establish specific T cell lines, to further determine the immune protective effect of immune cells, and then based on the identification of the protective T cell epitope.
In this laboratory, the recombinant protein of Plasmodium falciparum HGXPRT was expressed and purified by the Pichia yeast system.

【學位授予單位】：第二軍醫(yī)大學
【學位級別】：碩士
【學位授予年份】：2006
【分類號】：R392

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相關(guān)期刊論文 前2條

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本文編號：1384928