Evaluation of a parasite lactate dehydrogenase-based colloid gold-immunochromatography assay for diagnosis of Plasmodium falciparum

Abstract

Objective: To establish a colloid gold-immunochromatography assay (GICA) for detecting Plasmodium falciparum.

Methods: The monoclonal antibodies (mAbs) against lactate dehydrogenase of P. falciparum (LDHpf) were screened for preparation of GICA strips. With microscopic examination of the blood smears and PCR test as control, GICA was evaluated for its sensitivity, specificity and stability in the diagnosis of malaria in the outpatient clinics in China.

Results: Four hybridoma cell lines against LDHpf were prepared. Enzyme-linked immunosorbent assay demonstrated that the 4 mAbs reacted only with P. falciparum, but not with protein of normal human red cell, P. vivax, Toxoplasma gondii, or Schistosoma japonicam. All the 4 mAbs recognized a 33 kD protein designated as LDHpf as shown by Western blot analysis. Compared with the microscopic examination of blood smears and PCR test, GICA had the sensitivities of 88.37% and 86.67% and the specificities of 95.65% and 97.78%, respectively. Concordance between microscopic examination and GICA for P. falciparum infection was 91.55%.

Conclusion: GICA established in this study is simple, rapid, sensitive and specific for detecting P. falciparum, and is potentially useful in developing reagent kits for clinical use.