Expression and isoforms of gp43 in different strains of Paracoccidioides brasiliensis

Individual exoantigens from 13 Paracoccidioides brasiliensis isolates were obtained and tested against a panel of 50 sera from patients with paracoccidioidomycosis by immunodiffusion test. The index of positivity varied from 20 to 100% according to the isolate. When these exoantigens were analysed by SDS-PAGE, eight presented high amounts of the glycoprotein gp43, two presented small amounts and in three there was no detectable gp43. The eight isolates presenting high amounts of gp43 were submitted to isoelectric focusing, blotted to nitrocellulose membranes, and revealed by monoclonal and polyclonal anti-gp43 antibodies. Four gp43 isoform profiles were obtained: profile A presenting pIs of 6.0, 6.2, 6.6 and 7.0, profile B presenting pIs of 6.4, 6.8 and 7.2, profile C presenting pI > 8.5 and profile D, presenting pIs of 5.8, 6.2 and 6.6. In each pattern observed, a major band with a distinct pI was detected. Despite this variation, our results strongly suggest an epitopic conservation among all isoforms analysed, since all of them were recognized by anti-gp43 monoclonal antibodies.