Antileptospiral activity in lower-vertebrate sera.

Normal serum from the painted turtle (Chrysemys picta), the snapping turtle (Chelydra serpentina), and the frog (Rana pipiens) were found to possess bactericidal activity towards Leptospira. Leptospires from both the parasitic and biflexa complexes were killed by these sera at high dilutions. This pattern differs from that of mammalian serum, as generally only the biflexa complex leptospires are killed by normal mammalian serum. The activity in C. picta serum was characterized as being complement dependent and not mediated by basic proteins. Because comple-inactivated C. picta serum regained leptospiricidal activity after the addition of fresh rabbit serum, antibody is also likely to participate in the killing activity. Further support that C. picta serum contained leptospiral antibodies was found by the detection of serotype-specific agglutinins.