ErpY-LemA: A breakthrough in human leptospirosis diagnosis.

Leptospirosis remains a significant public health concern worldwide, particularly in tropical regions, where its diagnosis is often challenging due to nonspecific symptoms and limitations of current diagnostic methods. In this study, we evaluated the diagnostic potential of the recombinant chimera ErpY-LemA constructed from two Leptospira proteins with known immunogenic properties. The chimera was successfully expressed in Escherichia coli and demonstrated strong antigenicity, effectively recognizing sera from hamsters infected with diverse Leptospira serovars, indicating its non-serovar-specific nature (P < 0.001). ELISA assays were conducted using 80 human sera previously characterized by MAT. In the acute phase, IgM detection achieved 95 % of sensitivity and specificity (cut-off = 0.15, AUC = 0.990; P < 0.001). In the convalescent phase, IgG detection showed 80 % sensitivity and 100 % specificity (cut-off = 0.16, AUC = 0.968; P < 0.001). When the unknown disease phase were assessed, both IgG and IgM ELISAs maintained high diagnostic performance, with sensitivities and specificities ≥95 % and AUC values above 0.98. These findings highlight the ErpY-LemA chimera as a promising antigen for the development of a rapid, cost-effective serological diagnostic test for human leptospirosis, with high sensitivity and specificity regardless of disease stage or infecting serovar.