Abstract: The invention relates to mutant CyaA/E570Q+K860 polypeptides suitable for use as proteinaceous vectors for delivering one or more molecules of interest into a cell, in particular into a cell expressing the CD11b receptor. The invention further relates to polypeptide derivatives suitable for eliciting an immune response in a host. The invention is more particularly directed to polypeptides derived from an adenylate cyclase protein (CyaA) either under the form of a toxin or of a toxoid, which are mutant polypeptides. Said mutant polypeptides are capable of retaining the binding activity of native CyaA to a target cell and preferably of also retaining the translocating activity of native CyaA through its N-terminal domain into target cells and furthermore have a pore-forming activity which is reduced or suppressed as compared to that of the native CyaA toxin.