Malaria is still a major health problem in Thailand and its incidence is currently rising in Korea. To identify a useful antigen for the diagnosis of malaria patients, a cDNA expression library from malaria parasites was constructed and screened out immunologically. One clone was selected in view of its predominant reactivity with the patient sera. The recombinant malaria parasite antigen (Pv30) with 27 kDa as a C-terminal His-tag fusion protein that was produced in Escherichia coli was identified through immunoblot analysis. The deduced amino acid sequence had the sequence homology with the merozoite surface protein 1 (MSP1) genes of Plasmodium falciparum and P. yoelii, each by 41% and 42%, respectively. Measurement of serum IgG and IgM antibody to Pv30 by enzyme-linked immunosorbent assay (ELISA) was evaluated as a serodiagnostic test for malaria patients in Thailand (endemic area) and Korea (recently reemerging area). The sensitivity of P. vivax, P. falciparum, and P. malariae was 96.3% (26 /27), 90.6% (29/32), and 100% (6/6), respectively, and the specificity was 63.5% (40/63) in Thailand samples. The sensitivity of P. vivax was 98.8% (88/89), and the specificity was 96.6% (86/89) in Korean samples. Pv30 appears to be a good and reliable recombinant antigen for serodiagonosis of malaria in a nonendemic area.
Amino Acid Sequence ; Animals ; Antibodies, Protozoan ; Enzyme-Linked Immunosorbent Assay/*methods ; Human ; Korea ; Malaria, Vivax/*diagnosis/immunology ; Merozoite Surface Protein 1/*analysis/genetics/immunology ; Molecular Sequence Data ; Plasmodium vivax/chemistry/immunology/*isolation & purification ; Sensitivity and Specificity ; Serologic Tests ; Support, Non-U.S. Gov't

Malaria is a major parasitic disease in tropical areas. Three to five hundred million people suffer from the disease and it kill a million people per year. Blood smear observation was developed for the diagnosis of malaria, but the examination needs skilled experts and exact diagnosis is time consuming. A kit based on immunochromatography can be a reliable and rapid method for clinical diagnosis, even in the hands of inexperienced personnel. However, all such currently developed kits can only diagnose P. falciparum malaria. In our previous report, the C-terminal region of P. vivax merozoite surface protein 1 (PvcMSP) was cloned and expressed in E. coli. In the present study, we developed an immunochromatographic kit using this PvcMSP for the diagnosis of specific antibody to P. vivax malaria in serum samples. The kit was used to examine sera from vivax malaria patients and non-malaria-infected person and the test showed 100% sensitivity (78/78) and 98.3% specificity (58/59). This result demonstrated that the immunochromatographic kit for P. vivax antibody detection is applicable for the rapid and precise diagnosis of P. vivax malaria.
Animals ; Antibodies, Protozoan/*analysis ; *Chromatography ; Human ; *Immunologic Techniques ; Korea ; Malaria, Vivax/*parasitology ; Plasmodium vivax/*immunology ; *Reagent Kits, Diagnostic/*standards