the present invention relates to gene transfer and gene therapy technology . more specifically , the invention provides compositions and methods for targeted virus delivery . the method utilizes a method of mixing the virus , which may be a recombinant virus which will express a protein of interest or a nucleic acid of interest , with a cell - targeting ligand , e . g ., transferrin . the virus and ligand are mixed without crosslinkers or agents which would covalently bond the virus and ligand . this simple mixing causes less inactivation than chemically linking the ligand to the virus and therefore results in a more active therapeutic composition than obtained by methods which utilize crosslinking agents .