Infection with Leptospira kirschneri Serovar Mozdok: First Report from the Southern Hemisphere.

Leptospirosis is a global zoonosis caused by pathogenic Leptospira spp. In this study, we characterized two Leptospira kirschneri serogroup Pomona serovar Mozdok isolates, one obtained from a dog and the other from a patient with severe leptospirosis, 4 years later. Histopathological analysis showed that both isolates caused severe tissue damage when used to infect hamsters. While L. kirschneri serogroup Pomona serovar Mozdok is endemic in animals in Europe, there is only one report of human leptospirosis in the literature. Although strains belonging to L. kirschneri serogroup Pomona have been identified in cases of human leptospirosis in Europe, serovar Mozdok has not yet been implicated. The 4-year interval between isolations and the fact that this is the first report of serovar Mozdok as the causative agent of human leptospirosis in the southern hemisphere, demonstrates its epidemiological importance to public health. Moreover, the presence of serovar Mozdok in Brazil has the potential to affect vaccine and diagnostic test development.

Highly virulent Leptospira borgpetersenii strain characterized in the hamster model.

Abstract. A recent study by our group reported the isolation and partial serological and molecular characterization of four Leptospira borgpetersenii serogroup Ballum strains. Here, we reproduced experimental leptospirosis in golden Syrian hamsters (Mesocricetus auratus) and carried out standardization of lethal dose 50% (LD50) of one of these strains (4E). Clinical disease features and histopathologic analyses of tissue lesions were also observed. As results, strain 4E induced lethality in the hamster model with inocula lower than 10 leptospires, and histopathological examination of animals showed typical lesions found in severe leptospirosis. Gross pathological findings were peculiar; animals that died early had more chance of presenting severe jaundice and less chance of presenting pulmonary hemorrhages (P < 0.01). L. borgpetersenii serogroup Ballum has had a considerable growth in human leptospirosis cases in recent years. This strain has now been thoroughly characterized and can be used in more studies, especially evaluations of vaccine candidates.

Recombinant Mycobacterium bovis BCG expressing the LipL32 antigen of Leptospira interrogans protects hamsters from challenge.

The bacillus Calmette--Guerin (BCG), a live attenuated Mycobacterium bovis strain is considered a promising candidate as a vector system for delivery of foreign antigens to the immune system. The gene coding for the Leptospira interrogans external membrane protein LipL32, a highly immunogenic antigen found in all pathogenic leptospira, was cloned into several mycobacterial vectors for expression in BCG. Hamsters immunized with recombinant BCG (rBCG) expressing LipL32 were protected against mortality (P