Abstract Aspergillus fumigatus (A.f.) the cause of invasive Aspergillosis (IA) has become a leading cause of death in immunosuppressed populations, due to the lack of effective therapies or vaccines. Studies using anti-A.f. monoclonal antibodies indicate that they can protect against IA. However, the lack of detailed information on the antigenic targets of protective anti-A.f. antibodies has hampered the development of an effective anti-A.f. vaccine. It is known that sialylated epitopes found on a variety of pathogens including fungi and Group B Streptococci (GBS) are involved in attachment to host cells, uptake by phagocytes, and complement activation. A.f. sialylated epitopes may therefore provide a potential target for new therapies. Our preliminary data show that a purified, calcium-dependent GBSIb-specific antibody, SMB19 (IgM,κ) also binds to A.f. and provides a degree of protection in a murine model of IA. Likewise, immunization of wild type and SMB19 VH bearing immunoglobulin transgenic mice with a GBSIb vaccine also provides protection. These results support our hypothesis that induction of GBSIb specific antibodies, perhaps supplemented with antifungal drugs, will lead to new vaccines or passive antibody prophylaxis to prevent and treat IA.