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

Background: 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. Methods: The LFA used 2 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 human immunodeficiency virus (HIV) disease from 5 centers across Vietnam. Results: 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 < .01), and clinical specificity was >95% in both specimen types. Clinical performance was similar to the EIA: sensitivity 95.4% versus 97.1%, P = .87 and specificity 95.6% versus 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 < .01). Conclusions: 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.