Leptospirose animal: estudos para o desenvolvimento de vacinas recombinantes

Abstract

Leptospirosis is a disease caused by pathogenic spirochetes of the Leptospira genus. This zoonosis of worldwide distribution causes veterinarian and public health issues, especially in underdeveloped and developing countries with tropical and subtropical climates. In veterinary medicine, leptospirosis is important both as a clinical problem, causing illness in domestic animals, and an economic problem, causing productive and reproductive losses in commercial herds. Vaccination of these animals is applied, however protection conferred by these conventional vaccines is limited, and the carrier status is not always avoided. Recombinant outer membrane proteins seem to be the most promising antigens to replace the traditional bacterins (whole cell inactivated preparations), but thus far none of the tested proteins have turned satisfactory results. The goal of this study was to assess recombinant antigens and vaccine preparations, regarding their capability of producing protective immunity in hamsters, against lethal leptospirosis. Moreover, heterologous protection was sought, and assessed. The prevalence anti-Leptospira antibodies in stray dogs from the city of Pelotas was assessed using serogroups Icterohaemorrhagie and Canicola antigens. Several experiments were conducted to assess the protective potential of previously described leptospiral proteins. Twenty seven proteins were used to immunize hamsters which were then challenged with virulent Leptospira. Furthermore, leading vaccine candidates, LipL32 and LigB, were assessed regarding their protective potential when co-administered with traditional bacterins in previously established heterologous challenge experiments. A total of 28.96% of the animals tested were seropositive for the disease in the prevalence assay. Of the 27 antigens tried, two were shown to have some protective potential. Although no protection was demonstrated in the coadministration experiment, leptospiral bacterins seem to have some immunestimulating activity.