Efeito das células leveduriformes de Paracoccidioides brasiliensis radioatenuadas na vacinação profilática e terapêutica em Paracoccidioidomicose experimental

Abstract

Paracoccidioides brasiliensis is a dimorphic fungus that causes paracoccidioidomycosis (PCM), the main systemic mycosis in Latin America. So far, there is no vaccine for this disease. Depending on the severity of the disease and the chosen antifungal therapy may be prolonged and have high rates of relapse. Thus, the search for new alternative prophylactic and/or effective treatment is needed. In this regard, yeast cells of P. brasiliensis (Pb18) attenuated by gamma irradiation (LevRad) have been evaluated for their immunogenic potential. First, the immunogenic capacity of LevRad was assessed in vitro in peritoneal macrophages obtained from BALB/c mice activated or not in culture with recombinant IFN-γ, and challenged with LevRad or unirradiated P. brasiliensis (Pb18), in tests for determining phagocytic activity, capacity fungicide, concentration of NO and secretion of cytokines. The efficacy of prophylactic vaccination was assessed in BALB/c mice immunized with LevRad, and two routes of immunization were tested, intravenous (i.v.) and subcutaneous (s.c.), varying the number of immunizations (two or three consecutive times). The protective response was measured 30 and 90 days after intratracheal (i.t.) challenge with Pb18. The potential of therapeutic vaccination was also evaluated 60 and 120 days after infection with Pb18 in BALB/c mice treated by i.v. immunization with LevRad and/or fluconazole. Organs (lungs, spleen and liver) were used for the detection of colony forming units (CFU), histopathologic analyzes, cell proliferation and cytokine. The sera were used to evaluate the efficacy of immunization and the profile of total IgG and its isotypes IgG1, IgG2a, IgG2b and IgG3. LevRad was able to stimulate phagocytosis in vitro, the secretion of high levels of TNF-α, IFN-γ, IL-10 and NO production. The results demonstrate the potential immunogenicity of LevRad in vitro and highlight the potential use of LevRad in a formulation anti-P. brasiliensis protective, capable of preventing the establishment of the disease or reducing morbidity associated with the PCM.