Paracoccidioides brasiliensis-reactive antibodies in Brazilian blood donors

In a survey for primary paracoccidioidomycosis (PCM) infection (and not the clinical disease), two groups of blood donors were analyzed. One study group was drawn from donors living in a rural area where PCM is endemic, and the other group from urban residents of a large city, São Paulo. Anti-Paracoccidioides brasiliensis (Pb) specific antibodies (IgG) in sera were analyzed by ELISA, using crude Pb exoantigens (exoAg) and purified specific Pb 43 kDa glycoprotein (gp43). The results showed that 21% of 700 rural samples and 0.9% of 350 urban samples were positive for exoAg and gp43. To avoid cross-reactions, the sera were adsorbed first with Histoplasma capsulatum antigens and secondly with Leishmania amazonensis antigens. In the first adsorption with H. capsulatum, reactivity to gp43 fell to 12.8% in the rural group and to 0% in the urban group. In the succeeding adsorption with L. amazonensis, this reactivity fell to 12.3% in the rural group. There was a statistically greater proportion of persons with gp43-reactive antibodies in rural group than in the urban group, indicating that rural residents had frequently become exposed to Pb and contracted primary, subclinical PCM. The present report is the first epidemiological study using ELISA to detect antibodies against gp43 in blood donors.