Novel monoclonal antibodies against Plasmodium falciparum histidine-rich protein 2: development and application in rapid diagnostic tests of malaria in hyperendemic regions of China and Myanmar.

Keren Kang,Hui Liu,Emmanuel E Dzakah,Wenmei Li,Mingquan Xie,Xiaochun Luo

doi:10.1186/s12866-015-0429-1

Abstract

BackgroundMalaria 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).MethodsThe 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.ResultsThe 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.ConclusionsThese 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.

Highlights

Malaria presents a considerable threat to public health
Malaria, a disease caused by Plasmodium species, is one of the oldest and largest health challenges affecting 40% of the world population [1]
We aimed to express the Histidine-rich protein 2 (HRP 2) exon II antigen retaining the essential epitopes that can serve as immunogens for use in developing monoclonal antibodies (mAbs) against HRP 2 for Point-of-Care Test (POCT) immunochromatographic assay, according to guiding principles formulated by the WHO [10]

Summary

Introduction

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. A disease caused by Plasmodium species, is one of the oldest and largest health challenges affecting 40% of the world population [1]. There were an estimated 627, 000 malaria deaths in 2012, including 91% in Africa, mainly caused by P. falciparum infection, the most lethal malarial plasmodia responsible for the cerebral form of the disease. 86% malaria deaths are children under 5 years of age [2,3,4]. These estimates rank malaria as one of the top three killers among infectious. Inaccurate and ineffective diagnosis of P. falciparum in these regions has resulted in drug resistant species, pointing to the need for improved diagnosis and monitoring of the disease. The methods recommended by WHO for P. falciparum diagnosis include microscopic examination, immunological tests, and PCR methods [7,8,9]

Objectives

Methods

Results