pOET5.1 (10ug) is a dual promoter baculovirus transfer vector designed for high level expression of two foreign genes simultaneously under the powerful AcMNPV polyhedrin (polh) promoter and the very late p10 promoter. The promoters are in opposite orientations to minimize recombination. The vector is smaller than other available transfer vectors (4623bp), which greatly facilitates the cloning steps. It has a ColE1 origin of replication and an ampicillin resistance gene for selection in E. coli. The polh sequences have been replaced by two multiple cloning sites containing unique restriction sites for insertion of the foreign genes in the correct orientation. The AcMNPV sequences flanking the gene in the transfer vector’s MCS allow recombination with the viral DNA to insert the expression cassette into the polh locus. pOET5.1 is compatible with any baculovirus system that utilises homologous recombination in insect cells.