Composition, serologic reactivity, and immunolocalization of a 120-kilodalton tube precipitin antigen of Coccidioides immitis

Abstract

Diagnosis of coccidioidomycosis largely depends on serologic tests. In this investigation, the enzyme-linked immunosorbent assay (ELISA) was used to detect patient immunoglobulin M (IgM) precipitin antibody binding to a 120-kilodalton (kDa) fraction previously isolated from an alkali-soluble, water-soluble extract of the arthroconidial wall and mycelial culture filtrate plus toluene lysate of Coccidioides immitis. Results of the serologic response to this tube precipitin antigen (TP-Ag) in the ELISA correlated well with results of immunodiffusion assays of 30 serum samples from patients. Immunoelectron microscopic examinations of arthroconidia and spherules were performed with patient IgM precipitin antibodies isolated from sera eluted over a solid-phase immunosorbent column containing the purified 120-kDa TP-Ag. The antibody probe located the 120-kDa TP-Ag on the walls of in vitro-grown arthroconidia and spherules. Pronase digestion and heating (100°C, 5 min) had no apparent effect on the activity of the 120-kDa TP-Ag, while periodate oxidation resulted in total loss of its immunodiffusion-TP activity. Analysis of the carbohydrate composition of the TP-Ag revealed xylose, 3-0-methylmannose (3-0-MM), mannose, galactose, and glucose. Competitive inhibition ELISAs were used to demonstrate that 3-0-MM is largely responsible for the reactivity of IgM precipitin antibodies with the 120-kDa TP-Ag. Synthetic 3-0-MM may be a useful probe for detection of anti-Coccidioides precipitin antibodies in the ELISA.

An arthroconidial-spherule antigen of Coccidioides immitis: differential expression during in vitro fungal development and evidence for humoral response in humans after infection or vaccination

“…The tube precipitin antigen, which frequently reacts with antibodies from patients with coccidioidomycosis, is also detectable on the spherule surface. It has been suggested for that antigen as well that its presentation to host cells may involve the sloughing component of the spherule envelope (9,41).…”

Antigen complex of Coccidioides immitis which elicits a precipitin antibody response in patients

“…We have reported that two electrophoretically distinct TP antigens can be initially separated from the F+L fraction of C. immitis by ConA chromatography (17). These two fractions were purified and identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) as 120-and 110-kDa glycoproteins (6,17). Resnick and coworkers (27) have reported that a 21-kDa serine proteinase isolated from the culture filtrate of the parasitic phase of C. immitis also demonstrates reactivity with precipitin antibody from sera of patients with coccidioidomycosis.…”

Localization of the tube precipitin and complement fixation antigens of Coccidioides immitis by immunoelectron microscopy with murine monoclonal antibodies

“…The immunolocalization of the TP antigen has been evaluated in a previous study by Cole et al (4) using human anti-TP antibodies. The antibodies were isolated from patients' sera by immunoadsorption on 3-O-methylmannose, a carbohydrate which has been shown to react with anti-TP antibodies (4,5). In immunoelectron microscopic analyses of presegmented spherules, the investigators reported that the TP antigen was present within the inner cell wall, being detected at the highest concentration along the plasmalemma (4).…”

“…The magnitude of the CF antibody response, as measured by serial dilutions of the patient's serum or other biofluid, provides an index of disease involvement. Low titers generally reflect localized disease involving the lungs or a single extrapulmonary site, whereas high titers are consistent with extensive multifocal disease.Previous investigations have established that the TP antigen is a high-molecular-weight, heat-stable polysaccharide or polysaccharide-protein complex (4,5,8,9,15,25) which can be extracted from cell walls by enzymatic treatment (7) or by incubating the walls in 1 N NaOH (10). The CF antigen has been characterized as a heat-labile protein or glycoprotein (8,12,23,24), and although its cellular localization has not been established, evidence suggests that it is of cytoplasmic origin (7,17,23,24).…”