Compositions and methods are provided that relate to a recombinant virus-based vector, e.g., a baculovirus-based vector, that allows the expression of an exogenous target protein in non-permissive cells (e.g., non-permissive insect cells or mammalian cells) in the absence of expression of a detectable selection marker. The vector includes a nucleic acid sequence encoding a detectable selection marker which is controlled by a promoter that is active in host cells used to screen for recombinant virus but is silent in the non-permissive cell used for expression of the exogenous target protein. The vector also includes an exogenous nucleic acid sequence encoding a target protein under the control of a promoter that is active in the non-permissive cell. This system allows the selection marker to be expressed during viral plaque screening, but not while the target protein is being produced.
