Immunodiagnosis of Invasive Fungal Disease by Rapid Detection of Mannanemia

Abstract

Invasive fungal disease (IFD) is a leading cause of mortality among hospitalized patients in the developed world. The causative organisms commonly include Candida spp., Aspergillus fumigatus, Histoplasma capsulatum, Rhizopus oryzae, Fusarium soloni, and Mucor circinelloides. Effective treatment of IFD relies on the administration of anti-fungal medication in the early stages of disease; however, the clinical symptoms of fungal and bacterial infections are closely related, and oftentimes it is difficult to differentiate between them. Moreover, anti-bacterial medication is ineffective against IFD and may actually enhance disease. The overall goal of this dissertation was to lay the groundwork for the development of active components to be used in diagnostic tests that distinguish IFD from bacterial infection. Previous work demonstrated that mannans - sugars found on the surface of many fungi - may be useful biomarkers for IFD for several reasons including i) the overall prevalence of mannan in the fungal cell wall, ii) the lack of mannan production by bacteria, and iii) the reported abundance of mannans shed into patient fluids during active infection. Although these qualities make fungal mannans excellent biomarkers, in truth they have not been fully utilized because their biochemical properties inhibit the generation of specific detection reagents (antibodies) by traditional approaches. To overcome this obstacle, the work in this dissertation developed and optimized methods for inducing anti-mannan antibody responses in rabbits, rats, and mice. The methods that were developed allow for isolation of antibody that can be incorporated into many diagnostic platforms.