Kang Keren, Dzakah Emmanuel E, Li Wenmei, Xie Mingquan, Luo Xiaochun, Liu Hui
School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006, China.
National Engineering Laboratory of Point-of-Care Tests, Guangzhou Wondfo Biotech Co. Ltd, Guangzhou, 510663, China.
BMC Microbiol. 2015 May 12;15:98. doi: 10.1186/s12866-015-0429-1.
Malaria presents a considerable threat to public health. Histidine-rich protein 2 (HRP 2) is the major protein released into human blood upon infection by Plasmodium falciparum. In this study, we aimed to evaluate the immunogenicity of HRP 2 exon II and the efficacy of novel monoclonal antibodies (mAbs) against HRP 2 for Point-of-Care Test (POCT).
The recombinant protein was expressed in soluble form in E. coli and used to immunize mice for mAb production. Two IgG1 mAbs (1A5 and 1C10) with high affinity, specificity and sensitivity for both native and recombinant HRP 2 were selected after fusion of mouse spleen with myeloma cells. The affinity constant of 1A5 and 1C10 were 7.15 and 4.91 × 10-7 L/mol, respectively. Subsequently, an immunochromatograhic assay was used for screening of clinical samples in endemic regions of China and Myanmar.
The immunochromatographic test retrospectively showed an overall sensitivity of 99.07%, and specificity of 100%. Sensitivity at parasite densities < 200, 200-2000, and > 2000 parasites/μL was 87.5, 98.7, and 100%, respectively.
These results suggest that HRP 2 exon II contains immunogenic sites similar to those of the native antigen and can be used for the development of mAbs suitable for malaria diagnosis in endemic communities.
疟疾对公共卫生构成重大威胁。富含组氨酸的蛋白2（HRP 2）是恶性疟原虫感染人体后释放到血液中的主要蛋白。在本研究中，我们旨在评估HRP 2外显子II的免疫原性以及新型抗HRP 2单克隆抗体（mAb）用于即时检验（POCT）的效果。
重组蛋白在大肠杆菌中以可溶形式表达，并用于免疫小鼠以制备单克隆抗体。将小鼠脾脏与骨髓瘤细胞融合后，筛选出两种对天然和重组HRP 2均具有高亲和力、特异性和敏感性的IgG1单克隆抗体（1A5和1C10）。1A5和1C10的亲和常数分别为7.15和4.91×10-7 L/mol。随后，采用免疫层析法对中国和缅甸流行地区的临床样本进行筛查。
免疫层析试验回顾性显示总体敏感性为99.07%，特异性为100%。在寄生虫密度<200、200 - 2000和>2000个寄生虫/μL时的敏感性分别为87.5%、98.7%和100%。
这些结果表明，HRP 2外显子II包含与天然抗原相似的免疫原性位点，可用于开发适用于流行社区疟疾诊断的单克隆抗体。
