Cryptic species of Paracoccidioides brasiliensis: impact on paracoccidioidomycosis immunodiagnosis

We aimed to evaluate whether the occurrence of cryptic species ofParacoccidioides brasiliensis, S1, PS2, PS3 andParacoccidioides lutzii, has implications in theimmunodiagnosis of paracoccidioidomycosis (PCM). Small quantities of the antigengp43 were found in culture filtrates of P. lutzii strains andthis molecule appeared to be more variable within P. lutziibecause the synonymous-nonsynonymous mutation rate was lower, indicating anevolutionary process different from that of the remaining genotypes. Theproduction of gp43 also varied between isolates belonging to the same species,indicating that speciation events are important, but not sufficient to fullyexplain the diversity in the production of this antigen. The culture filtrateantigen AgEpm83, which was obtained from a PS3 isolate, showed large quantitiesof gp43 and reactivity by immunodiffusion assays, similar to the standardantigen (AgB-339) from an S1 isolate. Furthermore, AgEpm83 was capable ofserologically differentiating five serum samples from patients from the Botucatuand Jundiaí regions. These patients had confirmed PCM but, were non-reactive tothe standard antigen, thus demonstrating an alternative for serologicaldiagnosis in regions in which S1 and PS2 occur. We also emphasise that it is notadvisable to use a single antigen preparation to diagnose PCM, a disease that iscaused by highly diverse pathogens.