Isolation of a novel DNA aptamer against LipL32 as a potential diagnostic agent for the detection of pathogenic Leptospira

Leptospirosis is a potentially life-threatening zoonosis caused by pathogenic Leptospira and for rapid diagnostics, direct detection is desirable. LipL32 protein is the most suitable biomarker for direct detection. DNA aptamers are sought to be generated against LipL32 by Systemic Evolution of Ligands via Exponential Enrichment (SELEX). LepDapt-5a is the most potent aptamer candidate among all the candidates, as determined by direct Enzyme-linked Aptasorbent Assay (ELASA). LepDapt-5a was predicted to form a G-quadruplex structure as predicted by QGRS Mapper and validated experimentally by direct ELASA. The diagnostic potential of the aptamer was further tested on a direct and sandwich ELASA platform. A LOD of 10(6) mL(-1) and 10(5) mL(-1) were estimated by direct and sandwich ELASA platforms, respectively, which are within the range associated with leptospiremia levels. The dot blot assay developed was able to attain a LOD of 10(4) CFU mL(-1) against pathogenic Leptospira, which is also within the leptospiremia level. This is the first-ever DNA aptamer and hybrid-heterodimeric aptamer constructed against LipL32. The diagnostic potentiality of the LepDapt-5a DNA aptamer was proven on three major diagnostic platforms, which are direct ELASA, sandwich ELASA, and aptamer-based dot assay.

Automated summary

Leptospirosis is a potentially life-threatening disease caused by a bacteria called Leptospira. To improve the speed and accuracy of diagnosis, researchers have developed a DNA aptamer called LepDapt-5a that can directly detect the presence of LipL32 protein, a biomarker for Leptospira. The aptamer was successfully tested on three different diagnostic platforms, showing its potential for rapid and accurate detection of Leptospira.