Broadly reacting precipitating and agglutinating antigen of leptospirae

Publisher Website
Google Scholar
Abstract
A saprophytic Leptospira biflexa strain of equine origin was found which cross-reacts with immune rabbit antisera to 14 pathogenic L. interrogans serotypes. Sera from goats experimentally inoculated with the saprophyte showed multiple low-level cross-agglutination reactions against a battery of live L. interrogans serotypes. Sonically treated and saline-extracted suspensions of the L. biflexa strain and serotypes L. canicola, L. icterohaemorrhagiae and L. pomona yielded a common precipitating protein antigen that was detected by immunodiffusion and immunoelectrophoresis with all of the antileptospiral sera examined. In cross-absorption and gel diffusion tests, the precipitnogen from each of the strains was identical. Formaldehyde treatments and heating at 100.degree. C suggest that the cellular location of the common antigen is somatic or subsurface, and Sephadex G-200 gel filtration enabled the isolation of the active fraction of the L. biflexa antigen. Monoprecipitin sera against the common antigen of L. biflexa was produced by immunizing rabbits with specific precipitates in agar. In gel diffusion and immunolectrophoresis tests the antisera with each of the soluble antigens developed a single precipitin formation, and the antisera agglutinated formolized and heated whole-cell suspensions of serotypes L. canicola, L. icterohaemorrhagiae and L. pomona at low dilutions. The soluble L. biflexa antigen was evaluated as an immunogen and in passive immunity tests for protection against death and kidney infection in hamsters. No cross-protection occurred when the hamsters were challenged with virulent leptospires. The animals vaccinated or administered hamster immune serum before challenge died earlier than the control animals.