This disclosure provides a multimeric human immunodeficiency virus (HIV)protein binding molecule, e.g., andimeric IgA or a pentameric or hexameric IgM binding molecule, comprising atleast two bivalent binding units, or variants orfragments thereof, each comprising at least two antibody heavy chain constantregions or fragments thereof, wherein each heavy chainconstant region or fragment thereof is associated with an HIV antigen bindingdomain. Also provided are compositions comprisingthe multimeric binding molecules, polynucleotides encoding the multimericbinding molecules, and methods to make and use themultimeric binding molecules.
