Methods and compositions are provided for delivering a polynucleotide encodinga gene of interest to a target cell using a virus. The virus envelopecomprises a cell-specific binding determinant that recognizes and binds to acomponent on the target cell surface, leading to endocytosis of the virus. Aseparate fusogenic molecule is also present on the envelope and facilitatesdelivery of the polynucleotide across the membrane and into the cytosol of thetarget cell. The methods and related compositions can be used for treatingpatients having suffering from a wide range of conditions, includinginfection, such as HIV cancers, such as non-Hodgkins lymphoma and breastcancer and hematological disorders, such as severe combined immunodeficiency.
