Vaccinal evaluation and biochemical caracterization of thermolysin of Leptospira interrogans

Abstract

Leptospirosis is an important worldwide zoonosis and a public health issue. Some microorganisms developed multiple strategies to escape from the immune system. Pathogenic leptospirosis acquired immune evasion mechanisms, especially to escape from the complement system. Recently, we demonstrated that proteins secreted by pathogenic leptospires are able to inhibit the activation of the complement system. In addition, we identified in the culture supernatants a protease called termolysin, able to cleave certain complement proteins. Considering that, we believe that is very important to evaluate the vaccinal potential of thermolysin and characterize this enzyme (Sub-project 1). We will immunize hamsters with thermolysin using alumen hydroxide and challenge them later with pathogenic leptospire suspensions. The positive control will be formed by hamsters treated with a commercial vaccine (FarrowsureB, Pfizer) and another group will be treated only with PBS in the adjuvant. Blood samples will be withdrawn to monitor the production of anti-thermolysin antibodies. Histopathological analysis and bacterial load will be determined in the survived animals. We will also explore the cleavage of membrane attack complex proteins (C5b, C6, C7, C8 e C9) by thermolysin and culture supernatants of several species of pathogenic leptospires (Sub-project 2). (AU)