Molecular characterization of Schistosoma mansoni tegument annexins and comparative analysis of antibody responses following parasite infection
Molecular characterization of Schistosoma mansoni tegument annexins and comparative analysis of antibody responses following parasite infection
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DOI：
10.1016/j.molbiopara.2019.111231
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发表时间：
2019-12-01
影响因子：
1.5
通讯作者：
Jones, Malcolm
中科院分区：
文献类型：
--
作者：
Leow, Chiuan Yee;Willis, Charlene;Jones, Malcolm
血吸虫是一种寄生的血吸虫，全世界大约有2.5亿人感染。这种被称为血吸虫病的疾病是仅次于疟疾的第二大热带寄生虫病。吡喹酮是目前获准用于血吸虫病的唯一有效药物，人们对该药物的耐药性感到担忧。为了在流行地区提供长期保护，已经在研制血吸虫病疫苗方面作出了许多努力。表面相关蛋白，特别是在体壁或被膜中表达的蛋白，已被提议作为潜在的疫苗靶点。其中，膜联蛋白被认为对这一顶膜系统的稳定性至关重要。在此，我们介绍了四种同源膜联蛋白的结构和免疫生化特性，即膜联蛋白B30、膜联蛋白B5a、膜联蛋白B7a和膜联蛋白B5b。生物信息学分析表明，本研究未发现任何膜联蛋白的信号肽。进一步分析表明，所有四种膜联蛋白都具有一个由短但可变的n端区域和一个包含四个同源膜联蛋白重复序列（iv）的长c端核心组成的初级结构，其中包含五个α -螺旋。采用定量PCR方法评估各膜联蛋白的生命周期表达谱。结果表明，4种同源膜联蛋白在卵期总体转录水平均较低，但在尾蚴（入侵血吸虫幼虫）向血吸虫（入侵后幼虫）过渡后转录水平逐渐升高。圆形二色性（CD）表明rAnnexin B30、rAnnexin B5a和rAnnexin 7a是折叠的，显示出富含字母螺旋的二级结构。当rAnnexin B30、rAnnexin B5a和rAnnexin 7a在Ca2+存在下孵育时，膜结合亲和力增强。本研究中评估的所有膜联蛋白成员都免疫定位于被膜，免疫反应性也发生在成年寄生虫的细胞和肌肉中。四种重组膜联蛋白均具有免疫反应性，并能被感染曼氏梭菌的小鼠血清识别。综上所述，这些研究结果揭示了曼氏梭菌膜联蛋白B30、膜联蛋白B5a、膜联蛋白B7a和膜联蛋白B5b在宿主-寄生虫相互作用中的分子特征，并强烈提示这些分子可能是疫苗或诊断开发的有用候选分子。
Schistosomes are parasitic blood flukes that infect approximately 250 million people worldwide. The disease known as schistosomiasis, is the second most significant tropical parasitic disease after malaria. Praziquantel is the only effective drug currently licensed for schistosomiasis and there are concerns about resistance to the drug. There has been much effort to develop vaccines against schistosomiasis to produce long-term protection in endemic regions. Surface-associated proteins, and in particular, those expressed in the body wall, or tegument, have been proposed as potential vaccine targets. Of these, annexins are thought to be of integral importance for the stability of this apical membrane system. Here, we present the structural and immunobiochemical characterization of four homologous annexins namely annexin B30, annexin B5a, annexin B7a and annexin B5b from S. mansoni. Bioinformatics analysis showed that there was no signal peptide predicted for any annexin in this study. Further analysis showed that each of all four annexin protein possesses a primary structure consisting of a short but variable N-terminal region and a long C-terminal core containing four homologous annexin repeats (IIV), which contain five alpha-helices. The life cycle expression profile of each annexin was assessed using quantitative PCR. The results shoWed that the overall transcript levels of the each of four homologous annexins were relatively low in the egg stage, but increased gradually after the transition of cercariae (the invasive schistosome larvae) to schistosomula (the post-invasive larvae). Circular dichroism (CD) demonstrated that rAnnexin B30, rAnnexin B5a and rAnnexin 7a were folded, showing a secondary structure content rich in alphahelices. The membrane binding affinity was enhanced when rAnnexin B30, rAnnexin B5a and rAnnexin 7a was incubated in the presence of Ca2+. All annexin members evaluated in this study were immunolocalized to the tegument, with immunoreactivity also occurring in cells and in muscle of adult parasites. All four recombinant annexins were immunoreactive and they were recognized by the sera of mice infected with S. mansoni. In conclusion, the overall results present the molecular characterization of annexin B30, annexin B5a, annexin B7a and annexin B5b from S. mansoni in host-parasite interactions and strongly suggest that the molecules could be useful candidates for vaccine or diagnostic development.