人工多表位嵌合抗原用于恶性疟疾血清学监测的可行性研究

发布时间：2018-11-13 15:42

【摘要】：由疟原虫感染引起的虫媒传染病疟疾虽然仍然严重威胁着人类的健康,但是随着大量防控措施的开展,全球疟疾死亡率和发病率都已显著下降,而且很多国家和地区已经进入疟疾消除阶段。在该阶段,加强疟疾监测,有效的评估疟疾传播强度发挥着重要的作用。随着疟疾传播强度的降低,传统指标(昆虫接种率EIR)不再适用,而高灵敏性的血清学方法则受到越来越多的重视,但是该方法的关键在于选择合适的抗原标志。目前研究者的目光主要集中在恶性疟原虫固有抗原,例如AMA-1, MSP-119,MSP2等,而这些抗原各有其局限性。本科室前期利用表位随机重组技术构建了多表位基因库,并用库免疫血清筛选出了免疫原性最佳、稳定性最好的人工多表位嵌合抗原M.RCAg-1和M.RCAg-3,前者含有来自8种恶性疟原虫特异性抗原的11个表位；后者含有15种表位和3种融合片段,同样来自8种恶性疟原虫特异性抗原。本研究比较分析了恶性疟疾病人血清对两种抗原的识别情况,优选M.RCAg-1作为血清学监测抗原,并发现该抗原：1)对恶性疟疾感染后产生的天然抗体敏感性强,而且与间日疟疾没有交叉反应；2)人群多态性低；3)抗M.RCAg-1抗体在人体内半衰期较短(数周至数月)。应用M.RCAg-1抗原对中缅边境(疟疾疫区)和海南省(既往疫区)居民血清进行抗体检测,发现疫区居民血清抗体水平高于北京(非疫区对照)；而海南省居民血清抗体水平与对照组无显著性差异。应用M.RCAg-1获得云南省三个村落的恶性疟疾传播强度(SCR)与海拔存在半对数关系,经数理推导,通过M.RCAg-1获得的SCR与EIR存在指数相关性。本研究的结果初步说明了人工多表位嵌合抗原M.RCAg-1用于恶性疟疾血清学监测的可行性：可用于评估短期内恶性疟疾传播强度；评价恶性疟疾防控措施的效果；并可用于确认恶性疟疾是否已消除。
[Abstract]:Although malaria, an insect-borne infectious disease caused by Plasmodium infection, still poses a serious threat to human health, with the implementation of a large number of control measures, the global malaria mortality and morbidity rate has decreased significantly, And many countries and regions have entered the stage of malaria eradication. At this stage, the strengthening of malaria surveillance and effective assessment of malaria transmission intensity play an important role. Along with the decrease of malaria transmission intensity, the traditional index (insect vaccination rate EIR) is no longer applicable, and the highly sensitive serological method is paid more and more attention, but the key of this method is to select the appropriate antigen marker. At present, researchers mainly focus on Plasmodium falciparum inherent antigens, such as AMA-1, MSP-119,MSP2, which have their own limitations. The multiepitope gene library was constructed by using epitope random recombination technique in the early stage of our department. The best immunogenicity and stability of artificial polyepitope chimeric antigens M.RCAg-1 and M.RCAg-3 were obtained by using library immune serum. The former contained 11 epitopes from 8 specific antigens of Plasmodium falciparum. The latter contains 15 epitopes and 3 fusion fragments, which are also derived from 8 Plasmodium falciparum specific antigens. In this study, we compared and analyzed the recognition of two kinds of antigens in the sera of patients with falciparum malaria. We selected M.RCAg-1 as the serological monitoring antigen, and found that the antigens were: 1) highly sensitive to the natural antibodies produced by falciparum malaria infection. There was no cross reaction with daily malaria. 2) low polymorphism in population, 3) shorter half life (weeks to months) of anti M.RCAg-1 antibody in human body. M.RCAg-1 antigen was used to detect the antibodies in the sera of the residents in the China-Myanmar border (malaria endemic area) and Hainan province (past epidemic area). The results showed that the serum antibody level of the residents in the epidemic area was higher than that in Beijing (non-epidemic area control). However, there was no significant difference in serum antibody level between Hainan residents and the control group. M.RCAg-1 was used to obtain the semi-logarithmic relationship between falciparum malaria transmission intensity (SCR) and altitude in three villages in Yunnan Province. The SCR obtained by M.RCAg-1 was exponentially correlated with EIR by mathematical deduction. The results of this study preliminarily demonstrated the feasibility of artificial multiepitope chimeric antigen (M.RCAg-1) for serological monitoring of falciparum malaria, which can be used to evaluate the transmission intensity of falciparum malaria in the short term, and evaluate the effectiveness of the measures to prevent and control falciparum malaria. And can be used to determine whether falciparum malaria has been eliminated.
【学位授予单位】：北京协和医学院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：R531.3

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