Evaluation of a monoclonal antibody–based dot-blot ELISA for detection of Leptospira spp in bovine urine samples

Abstract

To evaluate the efficacy of a novel monoclonal antibody (MAb)-based dot-blot ELISA for detection of Leptospira antigens in urine samples of cattle. Blood and urine samples of 45 test cattle from 5 farms in Chonburi province and 20 control cattle from 2 farms in Khon Kaen province in Thailand. Blood and urine samples were assayed (microscopic agglutination test and urine antigen test) for Leptospira infection by use of an MAb-based dot-blot ELISA, and results for the ELISA were compared with those for dark-field microscopy (DFM), microbial culture, and a polymerase chain reaction (PCR) assay. All urine samples with positive results for DFM, microbial culture, PCR assay, or > 1 of these tests also had positive results when tested by use of the MAb-based dot-blot ELISA, except for 1 sample that had positive results only for the PCR assay. Detection limits of the dot-blot ELISA were 10(3) leptospires/mL of urine and 9.3 ng of Leptospira homogenate. Comparison revealed that the diagnostic sensitivity, specificity, efficacy (accuracy), positive predictive value, and negative predictive value for the ELISA were in agreement with results for DFM (100%, 72.72%, 80%, 57.14%, and 100%, respectively), microbial culture (100%, 61.54%, 66.62%, 28.57%, and 100%, respectively), and PCR assay (95.45%, 100%, 91.77%, 100%, and 95.83%, respectively). The MAb-based dot-blot ELISA is suitable as a tool for detecting leptospires in urine samples of cattle.