DIFFERENCES IN REACTIVITY OF PARACOCCIDIOIDOMYCOSIS SERA WITH GP43 ISOFORMS

The glycoprotein gp43 from Paracoccidioides brasiliensis is the main a ntigenic component in paracoccidioidomycosis (PCM) because it is recog nized by 100% of PCM patients. It has also been shown that different f ungal strains produce gp43 with at least four isoform profiles. In thi s study, different isoform profiles from gp43, with pIs ranging from 5 .8 to 8.5, were affinity purified from various P. brasiliensis (B-339, S.S., 1925 and I-9) exoantigens. Because of the isoform heterogeneity , we questioned whether those isoform profiles could be similarly reco gnized by acute or chronic PCM patients. By using a specific and sensi tive method for detection of human IgG anti-gp43 antibodies, the monoc lonal antibody capture immunoassay, we report that not all gp43 isofor m profiles are equally recognized in PCM sera when anti-gp43 MAb 17c w as employed as capturing antibody. Our result showed that recognition of pI 8.5 gp43 isoform was significantly lower for both acute (56%) an d chronic patients (71%), compared with gp43 isoforms from the standar d strain B-339. On the other hand, when anti-gp43 MAb 8a, which recogn izes a different antigenic epitope was used to capture the different g p43 isoform profiles, all patient's sera reacted similarly. The result s described suggest that not all the antigenic epitopes expressed by g p43 are equally present in all P. brasiliensis strains.