Plasmodium falciparum liver stage antigen-1 (PfLSA-1) is one of the few antigens expressed exclusively in liver stage parasites. In this study, we evaluated the antibody responses against recombinant PfLSA-1 in naturally infected individuals in Myanmar. High levels of antibody responses (70.7%) were detected in 82 serum samples from 116 infected individuals, and IgG responses to PfLSA-1 principally composed of responses of IgG1 and IgG3 subclasses. These results show that PfLSA-1 elicits effective antibody responses in individuals infected with P. falciparum, and thus it could be not only an attractive candidate protein for vaccine development, but also a useful antigen for serodiagnosis of the infection.
Animals ; Antibodies, Protozoan/*blood/immunology ; Antigens, Protozoan/*immunology ; Humans ; Immunoglobulin G/blood ; Malaria, Falciparum/blood/epidemiology/*immunology ; Myanmar/epidemiology

Prompt and accurate diagnosis of malaria is the key to prevent disease morbidity and mortality. This study was carried out to evaluate diagnostic performance of 3 commercial rapid detection tests (RDTs), i.e., Malaria Antigen Pf/Pantrade mark, Malaria Ag-Pftrade mark, and Malaria Ag-Pvtrade mark tests, in comparison with the microscopic and PCR methods. A total of 460 blood samples microscopically positive for Plasmodium falciparum (211 samples), P. vivax (218), mixed with P. falciparum and P. vivax (30), or P. ovale (1), and 124 samples of healthy subjects or patients with other fever-related infections, were collected. The sensitivities of Malaria Ag-Pftrade mark and Malaria Antigen Pf/Pantrade mark compared with the microscopic method for P. falciparum or P. vivax detection were 97.6% and 99.0%, or 98.6% and 99.0%, respectively. The specificities of Malaria Ag-Pftrade mark, Malaria Ag-Pvtrade mark, and Malaria Antigen Pf/Pantrade mark were 93.3%, 98.8%, and 94.4%, respectively. The sensitivities of Malaria Ag-Pftrade mark, Malaria Antigen Pf/Pantrade mark, and microscopic method, when PCR was used as a reference method for P. falciparum or P. vivax detection were 91.8%, 100%, and 96.7%, or 91.9%, 92.6%, and 97.3%, respectively. The specificities of Malaria Ag-Pftrade mark, Malaria Ag-Pvtrade mark, Malaria Antigen Pf/Pantrade mark, and microscopic method were 66.2%, 92.7%, 73.9%, and 78.2%, respectively. Results indicated that the diagnostic performances of all the commercial RDTs are satisfactory for application to malaria diagnosis.
Antigens, Protozoan/blood ; Cross-Sectional Studies ; *Diagnostic Techniques and Procedures/instrumentation ; Endemic Diseases/statistics & numerical data ; Humans ; Malaria/*diagnosis/epidemiology/parasitology ; Malaria, Vivax ; Plasmodium falciparum/genetics/immunology/*isolation & purification ; Reagent Kits, Diagnostic ; Thailand/epidemiology