Evidence of cross-protection within Leptospira interrogans in an experimental model

Killed whole-cell preparations were used as bacterins against leptospirosis . As this type of protection is considered to be serogroup-specific, severa l serogroups were added to the usual vaccines, and the most pathogenic sero var was chosen for each group. Different leptospire extracts were evaluated for their protective capacity against acute lethal leptospirosis in gerbil s (Meriones unguiculatus). Total extracts induced complete protection again st homologous challenges and partial protection against heterologous challe nges. LPS fractions protected against homologous but not heterologous chall enges, whereas protein extract induced significant protection against both types of challenge. Thus, cross-protection within L. interrogans was relate d to the protein extract. (C) 2000 Elsevier Science Ltd. All rights reserve d.