A novel monoclonal antibody against enolase antigen of Aspergillus fumigatus protects experimental aspergillosis in mice

Aspergillus fumigatus is one of the most common opportunistic fungal pathogens responsible for a variety of diseases in human, from allergic bronchopulmonary aspergillosis to chronic pulmonary aspergillosis, mostly in immunocompromized patients. In this study, one monoclonal antibody MAb R-5 (IgM) raised against enolase cell surface protein of A. fumigatus exhibited significant inhibition of spore germination in A. fumigatus (88.3%), Aspergillus flavus (57.4%) and Aspergillus niger (30.6%). The MAb R-5 also showed in vitro fungicidal activity against these species as follows: A. fumigatus (24.1%), A. flavus (13.3%) and A. niger (8.8%). These findings were supported by the indirect immunofluorescence microscopy, where the antibody showed binding with germinated spores and hyphae of A. fumigatus as well as A. flavus and A. niger. In vivo protective effect of MAb R-5 was evaluated in BALB/c mice challenged intravenously with A. fumigatus spores, where a significant reduction in CFU (85.9%) was observed in kidney tissue. The mean survival time of mice treated with MAb R-5 (18.5 days) was also enhanced compared to control (6.5 days). These results indicate that MAb R-5 could be valuable in diagnosis as well as in the treatment of broad range of Aspergillus infections.