Background Talaromycosis, caused by the thermally dimorphic fungus Talaromyces marneffei , is a life-threatening opportunistic infection in individuals with advanced immunodeficiency, particularly people living with HIV in endemic regions of Southeast Asia. Early diagnosis is essential to reduce morbidity and mortality; however, conventional diagnosis relies mainly on fungal culture, which is time-consuming and has limited sensitivity. Methods We developed and clinically evaluated a direct sandwich enzyme-linked immunosorbent assay (ELISA) using a biotin-labeled monoclonal antibody (4D1) for the detection of T. marneffei cytoplasmic yeast antigen in serum. The assay employed the same monoclonal antibody for both capture and detection in a double-recognition format. Analytical performance, cross-reactivity, and clinical diagnostic accuracy were systematically evaluated. Results No cross-reactivity was observed among the tested fungal antigens under the experimental conditions. The analytical limit of detection (LOD) in pooled human serum was 19.398 μg/mL. Clinical evaluation included 79 culture-confirmed talaromycosis cases and 381 non-talaromycosis controls. At an optimized optical density cut-off of 0.268, the assay demonstrated a sensitivity of 88.61% (95% confidence interval CI 79.47-94.66%) and a specificity of 96.06% (95% CI 93.59-97.78%). Conclusions The biotin-labeled 4D1 sandwich ELISA provides a rapid and accurate diagnostic method with good concordance to culture and may support improved clinical diagnosis of talaromycosis. Its potential application for treatment monitoring requires further validation.
Wei et al. (Tue,) studied this question.