Evaluation of recombinant Leptospira antigen-based enzyme-linked immunosorbent assays for the serodiagnosis of leptospirosis

There is an urgent need for development of new serodiagnostic strategies fo r leptospirosis, an emerging zoonosis with worldwide distribution. We have evaluated the diagnostic utility of five recombinant antigens in enzyme-lin ked immunosorbent assays (ELISAs) for serodiagnosis of leptospirosis. Sera from 50 healthy residents of a high-incidence region were used to determine cutoff values for 96% specificity. In paired sera from 50 cases of leptosp irosis confirmed by the microscopic agglutination test, immunoglobulin G (I gG) but not IgM reacted with the recombinant leptospiral proteins. The reco mbinant LipL32 IgG ELISA had the highest sensitivities in the acute (56%) a nd convalescent (94%) phases of leptospirosis. ELISAs based on recombinant OmpL1, LipL41, and Hsp58 had sensitivities of 16, 24, and 18% during the ac ute phase and 72, 44, and 32% during convalescence, respectively. Compared to sera from healthy individuals, patient sera did not react significantly with recombinant LipL36 (P > 0.05). Recombinant LipL32 IgG ELISA demonstrat ed 95% specificity among 100 healthy individuals, and specificities ranging from 90 to 97% among 30 dengue patients, 30 hepatitis patients, and 16 pat ients with diseases initially thought to be leptospirosis. Among 39 Venerea l Disease Research Laboratory test-positive individuals and 30 Lyme disease patients, 13 and 23% of sera, respectively, reacted positively with the rL ipL32 antigen. These findings indicate that rLipL32 may be an useful antige n for the serodiagnosis of leptospirosis.