Abstract: The invention relates to a recombinant viral particle capable of delivering a nucleic acid to mammalian cells, the particle including a member of a first specific binding pair capable of binding to a first receptor expressed on the surface of a cell so as to cause infection thereof, and a surface-exposed member of a second specific binding pair capable of binding to a second receptor generally not expressed on the surface of the cell, such that binding of the viral particle to the second receptor via the member of the second specific binding pair inhibits infection of the cell by the viral particle.

Abstract: The invention provides a recombinant viral particle for delivering a nucleic acid to mammalian cells, the particle comprising an MLV-env protein that binds to an MLV-env receptor expressed on the surface of a target cell so as to cause infection thereof, and a surface-exposed EGF that binds to an EGF receptor generally not expressed on the surface of the target cell, but expressed on non-target cells that also express the MLV-env receptor, such that binding of the viral particle to the EGF receptor via EGF inhibits infection of the non-target cell by the viral particle.