LipL32, an outer membrane protein of Leptospira, as an antigen in a dipstick assay for diagnosis of leptospirosis

Abstract

Microscopic agglutination test (MAT), as well as other serological assays that aimed at detecting antibodies to Leptospira, supplements the leptospirosis diagnosis based on the clinical features. Nevertheless, false positive results have been occasionally reported when the crude antigen was used in those antibody-based tests due either to the presence of antibodies stimulated by other antigenically related pathogens in the patient's serum, or the antibodies in the serum may be stimulated by a previously unrecognized Leptospira infection, especially in the disease endemic areas. Thus, the more refined antigen should improve the serodiagnostic accuracy. Among Leptospira spp., LipL32, which is a pathogenic Leptospira outer membrane protein (OMP), expressed by the bacteria grown both in vitro and in vivo. In this study, recombinant LipL32 protein was tested by a dipstick method for its potential in serodiagnosis of leptospirosis. Preliminary results suggest that the recombinant LipL32 is a good diagnostic detection reagent for specific Leptospira IgG. Diagnostic sensitivity and specificity of the Lip32 dipstick assay, when compared to those of MAT, were 100% and 98.33%, respectively.