Detection of Circulating gp43 Antigen in Serum, Cerebrospinal Fluid, and Bronchoalveolar Lavage Fluid of Patients with Paracoccidioidomycosis

Abstract

Paracoccidioidomycosis (PCM) is an important systemic fungal disease, particularly among individuals living and working in rural areas of endemicity in Latin America, who, without antifungal therapy, may develop fatal acute or chronic infection. For such patients, the detection of antibody responses by immunodiffusion is of limited value due to false-negative results. In contrast, the detection of Paracoccidioides brasiliensis gp43 circulating antigen may represent a more practical approach to the rapid diagnosis of the disease. Accordingly, an inhibition enzyme-linked immunosorbent assay (inh-ELISA) was developed for the detection of a 43-kDa P. brasiliensis-specific epitope incorporating a species-specific murine monoclonal antibody. With sera from patients with acute and chronic forms of the disease (n ‫؍‬ 81), the overall sensitivity of the test was found to be 95.1%, while specificity was found to be 97.5% compared to that with normal human sera from blood donors

Serology of paracoccidioidomycosis

“…Gómez et al [42] were the first to use monoclonal antibodies (Mabs) to detect the 87-kDa circulating antigen in PCM patients by inhibition ELISA (inh-ELISA), which showed 80.4% sensitivity. More recently, in our laboratory, the same technique was used to detect gp43 and gp70 in different specimens of PCM patients [43,44]. One of the main problems in the serodiagnosis of PCM based on antibody detection is the crossreaction obtained with sera from patients with other mycoses, mainly histoplasmosis and lobomycosis.…”

“…The use of the 43-kDa antigen detection system provide a rapid, sensitive, and specific mean to diagnose and differentiate between acute and chronic disease. Moreover, this test system's true potential may lie in tracking the course of antimycotic therapy by monitoring the reduction in fungal load as evidenced by a sequential reduction in antigen detected [43]. Figure 4 shows the results of gp43 detection in PCM patient's sera, and in control groups.…”

High molecular mass fraction in clinical isolates of Paracoccidioides brasiliensis

“…The gp43 glycoprotein, one of the most important immunodominant antigens of P. brasiliensis, has been extensively investigated, particularly in relation to diagnosis [20][21][22] . Gp43 has been detected at higher levels in PCM patient sera as circulating antigens 22 and in CSF and bronchoalveolar lavage (BAL) fluid samples from PCM patients 11 . However, recently the existence of a P. brasiliensis isolate presenting differences in this major antigen coding gene gp43 23,24 has been demonstrated and speculation of the possibility of a new species in the genus Paracoccidioides has been noted.…”

“…Besides gp43 11 , the 87-kDa molecule 15 , gp70 13 and the high molecular mass antigen with 160kDa 25 were also introduced as potential candidates for diagnosis and/or for follow-up of patients with PCM.…”

“…The inhibition ELISA methodology (inh-ELISA) is able to detect gp43 in 96.3% of PCM patients, mainly in those with the acute form of the disease (100%) 11 . Gp70 has also been detected in the urine or in cerebrospinal fluid (CSF) of PCM patients 12,13 .…”