Monoclonal Antibody ED1 as a Diagnostic Antibody for Human Invasive Pulmonary Aspergillosis

Abstract

Invasive fungal infections (IFIs) are a major issue in immunocompromised humans, with Aspergillus fumigatus being the second most common cause of IFI after Candida species. Due to the rising numbers of solid organ transplant and neutropenic patients, invasive pulmonary aspergillosis (IPA) is a serious concern with mortality rates reaching 90% in certain patient groups. Rapid and accurate diagnosis is essential to improve patient prognosis by allowing early initiation of the correct antifungal treatment. At present, diagnosis of IPA is problematic, with currently available tests relying on pan-fungal detection of the fungal cell wall component β-D-glucan or on detection of Aspergillus galactomannan. However, these biomarker tests have inherent limitations, with reports of false-positivity and lack of sensitivity and specificity. Therefore there is a need for an alternative diagnostic assay that can act as adjunct test to the rapid point-of-care lateral-flow assay previously developed for aspergillosis detection which incorporates the Aspergillus-specific IgG3 monoclonal antibody (mAb) JF5. This paper describes the characterisation of a newly developed murine mAb ED1, an IgG1, that binds to the epitope β1-5-galactofuranose on the extracellular galactomannoprotein antigen of Aspergillus fumigatus. Results show that ED1 can be used in combination with JF5 in a DAS-ELISA immunoassay format to detect IPA in a guinea pig model of disease. The work demonstrates that the laboratory-based DAS-ELISA can be used alongside the LFD to detect the diagnostic galactomannoprotein antigen in serum samples, providing confirmatory tests of invasive infection.