Latex Agglutination as a Rapid Screening Test and the Use of Recombinant LipL32 antigen- based Enzyme- linked Immunosorbent Assay for the Serodiagnosis of Human Leptospirosis

Leptospirosis is a widespread zoonotic disease that affects all mammals indifferent parts of the world. Clinical recognition of leptospirosis is challenging, and the definitive serologic diagnosis assay, the microscopic agglutination test (MAT) is the reference test for diagnosis, but it is time-consuming and requires the maintenances of several leptospiral strains to be used as antigens, live organisms creating a risk of laboratory-acquired infections. We prepared a rapid latex agglutination test (LAT) reagent for the detection of Leptospira- specific antibodies in human serum samples. The efficacy of the LAT was compared with two commercial rapid serologic tests, the LeptoTek Lateral Flow and the LeptoTek Dri-Dot with MAT as gold standard. A total of 419 human serum samples were analyzed by MAT, LAT, Lateral Flow, and Dri-Dot. By Using MAT as gold standard, the sensitivities for detection of leptospiral antibodies were 44.4% by Lateral Flow, 52.8% by Dri-Dot and 86.1% by LAT; specificities were95.2% by Lateral Flow, 82.5% by Dri-Dot, and 78.8% by LAT, respectively. On our study, LAT showed the best agreement with MAT (κ=0.62) and the agreement of the Lateral Flow and Dri-Dot with MAT was low (κ=0.44 and 0.37, respectively). These characteristics make LAT ideal for rapid screening for leptospirosis suspicious patients. Because more leptospiral outer membrane protein genes has been cloned and expressed. It is essential to provide a antigen for antibodies detection. The recombinant LipL32 protein expressed in Escherichia coli BL21 is used as antigen for enzyme-linked immunosorbent assay (ELISA) to screen leptospirosis suspected patients and 40 normal control sera. Sensitivity and specificity are 97.1% and 71.9% in IgG-ELISA, 80.3 % and 63.0% in IgM-ELISA. These findings indicate that LipL32 may be an useful antigen for the serodiagnosis of leptospirosis.