Stabilization of RDT target antigens present in dried Plasmodium falciparum -infected samples for validating malaria rapid diagnostic tests at the point of care

摘要

BackgroundMalaria rapid diagnostic tests (RDTs) are a great achievement in implementation of parasite based diagnosis as recommended by World Health Organization. A major drawback of RDTs is lack of positive controls to validate different batches/lots at the point of care. Dried Plasmodium falciparum -infected samples with the RDT target antigens have been suggested as possible positive control but their utility in resource limited settings is hampered by rapid loss of activity over time. MethodsThis study evaluated the effectiveness of chemical additives to improve long term storage stability of RDT target antigens (HRP2, pLDH and aldolase) in dried P. falciparum -infected samples using parasitized whole blood and culture samples. Samples were treated with ten selected chemical additives mainly sucrose, trehalose, LDH stabilizer and their combinations. After baseline activity was established, the samples were air dried in bio-safety cabinet and stored at room temperatures (~?25?°C). Testing of the stabilized samples using SD Bioline, BinaxNOW, CareStart, and First Response was done at intervals for 53?weeks. ResultsStability of HRP2 at ambient temperature was reported at 21–24?weeks while that of PAN antigens (pLDH and aldolase) was 2–18?weeks of storage at all parasite densities. The ten chemical additives increased the percentage stability of HRP2 and PAN antigens. Sucrose alone and its combinations with Alsever’s solution or biostab significantly increased stability of HRP2 by 56% at 2000?p/μL (p? ConclusionsThese findings confirm that stabilizing RDT target antigens in dried P. falciparum -infected samples using chemical additives provides field-stable positive controls for malaria RDTs.