The present invention provides a fusion polypeptide which can bind to a cellsurface binding moiety (e.g., a carbohydrate) and server as a ligand for acell surface polypeptide, as well as a vector comprising a nucleic acidencoding for such a fusion polypeptide, and a host cell comprising suchnucleic acid. The present invention also provides a composition comprising anantigen bearing target and such a fusion polypeptide, as well as a compositioncomprising a virus or a cell and such a fusion polypeptide. The presentinvention further relates to a method of modulating an immune response in ananimal using such compositions.