Caracterização fenotípica e sequenciamento do genoma de Leptospira kirschneri isolada de caso clínico humano

Abstract

Leptospirosis is a neglected zoonosis spread worldwide with more than 800,000 human cases each year. The disease is caused by pathogenic members of the genus Leptospira, which is classified in 10 species and more than 260 serovars, grouped in more than 30 serogroups. The main species associated with human cases of leptospirosis are L. interrogans, L. borgpetersenii and L. kirschneri. L. interrogans serogroup Icterohaemorrhagiae causes the majority of human leptospirosis cases in Brazil, where the tropical and subtropical climates favour the spread of the disease. Even though the climate in Pelotas is temperate, Leptospira infection rates (10 cases per 100 thousand inhabitants) are higher than other regions with tropical and subtropical climates (3.5 cases per 100 thousand inhabitants). Leptospirosis surveillance studies play a vital role against the disease through the identification of endemic species and sorovars to a given region. This work describes the characterization of a Leptospira strain isolated from an inhabitant of the rural area of Pelotas. The patient reported contact with water, cattle, dogs and rodents and presented classical symptomatology for leptospirosis. Multilocus sequence typing (MLST) determined the isolate to be a L. kirschneri serogroup Pomona serovar Mozdok. The genome of the isolate includes of 3,398 coding sequences, 39 tRNAs, 1 rRNA coding region and 34.6% G+C content. Chromosome I has 3,738,643 base pairs, and chromosome II has 335,634 base pairs, totalizing 4.07 Mb. Indirect immunofluorescence showed the expression of LigA and LigB virulence factors as well as the LipL32 protein. The isolate was capable of causing severe renal, hepatic and lung damage, as revealed by histopathological analysis and the presence of leptospiras in these tissues was confirmed by the imprint technique. This is the first report of isolation of L. kirschneri serovar Mozdok from a human patient in the Southern Hemisphere, according to the literature. Results presented herein are important for epidemiologic studies, as well as for the development of new vaccines and rapid diagnosis tests.