Development and Clinical Evaluation of a Novel Talaromyces marneffei Mp1p Lateral Flow Assay for Rapid Diagnosis of Talaromycosis.

Abstract

The diagnosis of talaromycosis, a life-threatening invasive fungal disease endemic in Southeast Asia, still relies on protracted culture methods. We report the development and clinical evaluation of a novel lateral flow assay (LFA) for the rapid diagnosis of talaromycosis. The LFA used two novel monoclonal antibodies targeting the Talaromyces marneffei-specific protein Mp1p. In a retrospective, case-cohort study, we evaluated the diagnostic performance of the Mp1p LFA against the reference standard of culture-proven talaromycosis from any clinical specimens, and compared to our validated Mp1p enzyme immunoassay (EIA) in paired plasma and urine samples from 239 talaromycosis and 160 non-talaromycosis participants randomly selected from cohorts of hospitalized adults with advanced HIV disease from five centers across Vietnam. The Mp1p LFA demonstrated an analytical limit-of-detection of 400 pg/mL, comparable to the EIA. No cross-reactivity with 16 common human fungal pathogens was observed. Clinical sensitivity was higher in urine compared to plasma (95.4% vs 88.7%, P < 0.01), and clinical specificity was >95% in both specimen types. Clinical performance was similar to the EIA: sensitivity 95.4% vs 97.1%, P = 0.87 and specificity 95.6% vs 97.5%, P = 1.0. Both the LFA and EIA were substantially more sensitive than conventional blood culture collected at the same time (95.4% vs 97.1% vs 77.8%, P < 0.01). The Mp1p LFA has excellent diagnostic performance, comparable to the EIA, is superior to blood culture, and has the potential to rapidly rule-in and rule-out talaromycosis at the point-of-care within 15 minutes without need for laboratory infrastructure.