Evaluation of LD Bio Aspergillus ICT lateral flow assay for IgG and IgM antibody detection in chronic pulmonary aspergillosis.


Stucky Hunter E, Richardson MD, Denning DW.
J Clin Microbiol. 2019 Jun 19. pii: JCM.00538-19.


Background: Detecting Aspergillus-specific IgG is critical to diagnosing chronic pulmonary aspergillosis (CPA). Existing assays are often cost- and resource-intensive and not compatible with resource-constrained laboratory settings. LDBio Diagnostics has recently commercialized a lateral flow assay based on immunochromatographic technology (ICT) that detects Aspergillus antibodies (IgG+IgM) in less than 30 minutes, requiring minimal laboratory equipment.Methods: 154 CPA patient sera collected at the National Aspergillosis Centre (Manchester, UK) and control patient sera from the Peninsula Research Bank (Exeter, UK) were evaluated. Samples were applied to the LDBio Aspergillus ICT lateral flow assay and results were read both visually and digitally. Results were compared with Aspergillus IgG titers in CPA patients, measured by ImmunoCAP specific IgG.Results: For proven CPA patients versus controls, sensitivity and specificity for the LDBio Aspergillus ICT were 91.6% and 98.0%, respectively. In contrast, the routinely-used ImmunoCAP assay exhibited 80.5% sensitivity for the same cohort (cut off of 40mgA/L). The assay is easy to perform but challenging to read when only a very faint band is present (5/154 samples tested). ImmunoCAP Aspergillus IgG titer was also compared with Aspergillus ICT test line intensity or rate of development with weak to moderate correlations.Conclusions: The Aspergillus ICT lateral flow assay exhibits excellent sensitivity for serological diagnosis of CPA. Quantifying IgG from test line intensity measurements is not reliable. Given the short run time, simplicity, and limited resources needed, the LDBio Aspergillus ICT is a suitable diagnostic tool for CPA in resource-constrained settings.