ABSTRACTLeptospirosis is a global zoonotic disease caused by differentLeptospiraspecies, such asLeptospira interrogans, that colonize the renal tubules of wild and domestic animals. Thus far, attempts to develop effective leptospirosis vaccines, both for humans and animals, have failed to induce immune responses capable of conferring protection and simultaneously preventing renal colonization. In this study, we evaluated the protective immunity induced by subunit vaccines containing seven different recombinantLeptospira interrogansouter membrane proteins, including the carboxy-terminal portion of the immunoglobulinlike protein A (LigAC) and six novel antigens, combined with aluminum hydroxide (alum) orSalmonellaflagellin (FliC) as adjuvants. Hamsters vaccinated with the different formulations elicited high antigen-specific antibody titers. Immunization with LigAC, either with alum or flagellin, conferred protective immunity but did not prevent renal colonization. Similarly, animals immunized with LigACor LigACcoadministered with six leptospiral proteins with alum adjuvant conferred protection but did not reduce renal colonization. In contrast, immunizing animals with the pool of seven antigens in combination with flagellin conferred protection and significantly reduced renal colonization by the pathogen. The present study emphasizes the relevance of antigen composition and added adjuvant in the efficacy of antileptospirosis subunit vaccines and shows the complex relationship between immune responses and renal colonization by the pathogen.
IRON LIMITATION AND EXPRESSION OF IMMUNOREACTIVE OUTER MEMBRANE PROTEINS IN LEPTOSPIRA INTERROGANS SEROVAR ICTEROHAEMORRHAGIAE STRAIN LAI
