Studies on gene analysis and immunological function of 47KD polypeptide of Plasmodium falciparum.

对疫区人群免疫状况的比较研究将阐明与保护性免疫相关的抗原表位。本研究用抗恶性疟原虫多克隆抗体从热带流行地区的人群和日本恶性疟疾患者身上采集。用免疫印迹法检测到感染急性期血清中有47kD分子(Pf47kD)，推测pf47kD是在疟疾感染早期诱导免疫反应的寄生虫表位。研制了pf47kD的单抗，用于研究pf47kD在寄生虫中的定位。激光扫描荧光显微镜显示，pf47kD位于发育中的裂殖体表面。对编码pf47kD序列的寄生虫基因进行了初步研究。从成群的恶性疟原虫中提取cDNA文库，将其连接到载体上，导入宿主细胞。用高效价多克隆抗体和单抗进行筛选。得到的pf47kD序列与人类基因序列一致。原因仍在研究中。同时，用高效液相色谱法对寄生虫抗原进行纯化，并进行序列分析，并将结果与上述结果进行对比研究。在现场研究中，通过使用慢性恶性疟原虫感染血清，突出了23kD的寄生虫分子。这种分子似乎引发了另一种保护性免疫反应。此外，还利用近交系小鼠和猴的动物模型，研究了细胞因子在保护性免疫中的作用。干扰素-γ和肿瘤坏死因子-α在疟疾感染中起保护作用，并可能在有害反应中起作用。

Comparative studies on immunue status of individuals living in the endemic areas will elucidate the antigen epitopes related to protective immunity. Present study was performed by using anti-P.falicparum polyclonal antibodies taken from individuals in the endemic tropical areas and also from patients who developed falciparum malaria in Japan. By an immunoblotting, electrophoresed 47kD molecule (pf47kD) was presented by the sera taken from the acute phase of the infection, thus it was presumed that pf47kD was a parasite epitope inducing immune reactions at an early stage of malaria infection. One monoclonal antibody was developed to study localization of pf47kD in the parasite. A lazer-scanning fluorescent microscopy rvealed that pf47kD was on the surface of developing schizont. Studies on parasite gene which encodes the pf47kD sequence was attempted. cDNA library from the clutured falciparum parasite was prepared and were ligated to vectors and were introduced into host cells. Screening was processed by using high titered polyclonal antibodies and the monoclonal antibody. the resulted pf47kD sequence was coincidental with an sequence of human gene. The reason is still on the study. Simultaneously, the parasite antigen was purified by using HPLC to analyze the sequence and results will be comparatively studied with the results shown above. In the field studies, a 23kD parasite moleculte was highlighted by the use of the sera from chronic type of P.falciparum infection. The molecule seemed to induce another type of protective immune reaction. In addition, roles of cytokines in the protective immunity was studied using animal models of inbred mice and monkeys. INF-gamma and TNF-alpha worked in the protection and probably in the detrimental reaction in malaria infection.