There is disclosed a retroviral vector comprising a primer binding site, a long terminal repeat and an RNA packaging sequence, wherein the RNA packaging sequence is located 3′ of the long terminal repeat and no long terminal repeat is located 3′ of the RNA packaging sequence such that reverse transcription initiated at the primer binding site does not lead to reverse transcription of the RNA packaging sequence into vector DNA in a target cell. Also described is a host cell, a virion, a pharmaceutical composition, a method and uses including or involving the vector described above. Further, a cell or transgenic animal produced by using the vector is also described.