Sandwich-type homogeneous chemiluminescence immunoassay based on nanoparticle toward detection of Aspergillus galactomannan antigen

Aspergillus species continue to be an important cause of life-threatening infection in immunocompromised patients and galactomannan (GM) is a popular biomarker in the diagnosis of invasive aspergillosis (IA). Here we developed and validated an amplified luminescent proximity homogenous assay-linked immunosorbent assay (AlphaLISA) for serum and bronchoalveolar fluid (BALF) GM based on this approach. Technological processes and reaction conditions were optimized. Study assessments included reproducibility, accuracy, stability, and cross reactivity experiments. Method comparisons with the commercial Platelia Aspergillus enzyme immunoassay (Bio-Rad Laboratories) were performed using 201 clinical serum and BALF samples. Under the optimized conditions, the total runtime of the AlphaLISA method was 40 min with simple operation. The percent coefficient variations (CVs%) were lower than 15%, and the recoveries were in the range of 90-110%. Of note, the proposed assay exhibited acceptable stability and did not display cross-reactivity with non-Aspergillus pathogens. Compared with the results from the Platelia kit, there was a satisfied overall qualitative agreement of 97.5% and overall quantitative correlation coefficient of 0.59. In all, we have successfully developed an alternative novel homogeneous nanoparticle-based immunoassay, which has shorter incubation time and easier protocol than the ones of conventional ELISA. It could serve as an alternative to the well-established Platelia assay for measurement of GM in serum and BALF.