E. coli proteins have been identified that are useful as carrier proteins to improve a response to a polysaccharide immunogen conjugated to such protein. In particular, AcfD precursor protein (orf3526 polypeptide), Flu antigen 43 protein (orf1364 polypeptide), and Sel1 repeat-containing protein (upec-5211 polypeptide) have been shown to be effective. Additionally, these E. coli proteins can enhance the immune response to glucans, particularly fungal glucans.