Uracil-DNA Glycosylase-Enhanced Loop-Mediated Isothermal Amplification Assays for Detection of Zoonotic Malaria Plasmodium Parasites.

BACKGROUND

Zoonotic malaria caused by simian Plasmodium species presents increasing diagnostic challenges in endemic regions.

METHOD: This study developed and evaluated malachite green-based loop-mediated isothermal amplification (MG-LAMP) assays for detecting five zoonotic malaria parasites (P. knowlesi, P. cynomolgi, P. inui, P. coatneyi, and P. fieldi). The assays enable rapid visual detection through a colorimetric change without requiring specialized equipment. To reduce carryover contamination, deoxyuridine triphosphate (dUTP) and uracil-DNA glycosylase (UDG) were incorporated into the reaction.

RESULT: All five UDG MG-LAMP assays demonstrated high analytical sensitivity, with limits of detection of 1 copy/µL for P. cynomolgi, P. coatneyi, and P. fieldi, and 10 copies/µL for P. knowlesi and P. inui. The assays showed 100% specificity, with no cross-reactivity among target species. Malachite green enabled clear visual discrimination between positive and negative reactions.

CONCLUSION

A simplified direct blood lysis method requiring less than 20 min was also developed to enable rapid DNA preparation without column-based purification. Overall, the MG-LAMP assays combined with UDG and rapid lysis provide a sensitive, specific, and practical approach for diagnosing zoonotic malaria, particularly in resource-limited endemic settings.