Avaliação da resposta humoral e antígenos imunodominantes em Calomys callosus infectados experimentalmente com Paracoccidioides brasiliensis

Abstract

Paracoccidioidomycosis (PCM) caused by a dimorphic fungus Paracoccidioides brasiliensis, is the main systemic mycosis of Latin America. Experimental models are important in the PCM study. The objective of this study was evaluate the specific humoral response (IgG, IgG1 and IgG2a) of Calomys callosus infected experimentally with P. brasiliensis and to identify patterns of antigenic recognition comparatively to susceptible (B10.A) and resistant (A/Sn) mice. The animals were infected with 0.6 x 105 yeasts de P. brasiliensis (Pb18 isolate). Lung, liver, spleen and serum samples were collected at 7, 15, 30, 60, 90 and 120 days after infection. We noticed that in the histological findings the infection evolved gradually in the studied groups, with more prominent inflammation in C. callosus, especially in the lung. In ELISA assay, the levels of IgG and IgG1 were similar for the three groups, but when we consider the IgG2a levels, C. callosus presented the lowest levels. In immunoblotting assays, the immunodominant bands (antigens) that were common to the three animals groups recognized by IgG1 were 117, 110, 95-100, 70, 43, 36 and 24kDa and by IgG2a were 95-100, 43 and 29kDa. Considering the IgG2a response, the frequency of antigenic recognition by the C. callosus serum and the band intensity were lesser than B10.A and A/Sn mice. In conclusion, C. callosus, inoculated with 0.6 x 105 P. brasiliensis yeasts, presented greater susceptibility to the infection, with a higher degree of tissue injuries, lower response of IgG2a and a lesser recognition of antigenic fractions with a lower intensity, when as compared to murine experimental model.