An improved baculovirus vector capable of expressing genes in mammalian or insect host cells, and the uses thereof are disclosed. The improved baculovirus vector includes in sequence: a promoter; a first nucleic acid operably linked to the promoter for expressing a first protein in the mammalian or insect host cells; a chimera internal ribosomal entry site (IRES) comprising a portion of an enterovirus (EV) IRES sequence at least 90% identical to SEQ ID NO: 1 and a portion of a Rhopalosiphum padi virus (RhPV) IRES sequence at least 90% identical to SEQ ID NO: 2; and a second nucleic acid operable linked to the portion of the RhPV IRES sequence for expressing a second protein in the mammalian or insect host cells.