Recombinant viruses have a full-length, functional lacZ gene resulting in the production of blue plaques. This allows for easy identification and purification. Bac-N-Blue DNA can be used with any polyhedrin promoter-based baculovirus transfer vector. Bac-N-Blue DNA is linearized at three sites, one of which is in a gene that is essential for viral propagation. This leads to a decrease in non-recombinant virus, making selection and purification of recombinant virus easy. In addition to the viral DNA, the Bac-N-Blue Transfection Kit contains Cellfectin Reagent for high transfection efficiency.