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Open Access Research

Plasmodium vivax aldolase-specific monoclonal antibodies and its application in clinical diagnosis of malaria infections in China

Emmanuel E Dzakah12, Keren Kang12*, Chao Ni12, Hong Wang12, Peidian Wu2, Shixing Tang2, Jihua Wang2, Jufang Wang1* and Xiaoning Wang3

Author Affiliations

1 School of Bioscience and Bioengineering, South China University of Technology, University City, Panyu District, Guangzhou 510006, China

2 National Engineering Laboratory of Rapid Diagnostic Tests, Guangzhou Wondfo Biotech Co., Ltd, Science City, Lizhishan Rd. No. 8Luogang District, Guangzhou 510663, China

3 Institute of Life Science, General Hospital of Chinese People’s Liberation Army, Beijing 100853, China

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Malaria Journal 2013, 12:199  doi:10.1186/1475-2875-12-199

Published: 12 June 2013

Abstract

Background

Most rapid diagnostic tests (RDTs) currently used for malaria diagnosis cannot distinguish the various Plasmodium infections. The development of a Plasmodium vivax specific RDTs with high sensitivity to sufficiently differentiate the two most common Plasmodium infections would be very crucial for disease treatment and control.

Method

Plasmodium vivax aldolase gene (PvALDO) was amplified from the extracted genomic DNA and constructed into pET30a vector. Plasmodium vivax aldolase protein was successfully expressed in Escherichia coli in soluble form and the overall purity was over 95% after one-step affinity chromatography purification. The purified products were used for the immunization of mice and rabbits. Rabbit polyclonal antibodies generated were deployed to develop a novel antibody-capture ELISA for hybridoma screening.

Results

Three PvALDO specific mAbs (14C7, 15F1 and 5H7) with high affinities were selected and used in immunochromatographic test strips. Clinical blood samples (n=190) collected from Yunnan (China) were used for evaluation and the RDT’s sensitivity for P. vivax was 98.33% (95% Confidence Interval (CI): 91.03% to 99.72%) compared with microscopic examination. There was specificity of 99.23% (95% CI: 95.77% to 99.87%) for P. vivax. Only one Plasmodium falciparum sample was detected among the P. falciparum samples (n=20). All Plasmodium malariae samples (n=2) as well as healthy uninfected samples (n=108) were negative. Overall performance of this RDT was excellent with positive predictive value (PPV) and negative predictive value (NPV) of 98.33% and 99.23%, respectively, at 95% CI and a very good correlation with microscopic observations (kappa value, K=0.9757). Test strips show high sensitivity even at 6.25 ng/ml of recombinant P. vivax aldolase (rPvALDO).

Conclusion

This study further elucidates the possibility of developing aldolase-specific RDTs which can differentiate the different Plasmodium infections and improve accurate diagnosis of malaria. This RDT could adequately differentiate between P. vivax and P. falciparum infections. The novel mAb screening method developed here could find application in the screening of highly specific antibodies against other antigens.

Keywords:
Plasmodium vivax; Aldolase; Malaria; Monoclonal antibodies; ELISA