Bovine IgM and IgG response to Leptospira interrogans serovar hardjo as measured by enzyme immunoassay

The enzyme-linked immunosorbent assay (ELISA) was used to detect specific IgG and IgG antibodies in the sera of cattle infected or immunized with Leptospira interrogans serovar hardjo. IgM appeared first but was quickly followed by IgG which persisted longer than IgM. The levels of antibody detectable by ELISA and by the microscopic agglutination test (MAT) did not correlate, suggesting that the two techniques measured different antigen--antibody systems. The transient nature of the IgM response as measured by ELISA indicates potential usefulness as a serodiagnostic test for detecting current leptospiral infections.