Disclosed and claimed is the promoter, full-length or truncated, of the persistence-associated gene 1 (pag1) of Hz-1 virus, vectors containing the promoter, including with exogenous coding DNA, methods employing the vectors, compositions employing the vectors and products therefrom, and probes and primers for the promoter or functional fragment thereof. The promoter of pag1 gene is strong and if not comparable, it is better than the promoter activity demonstrated in the polyhedrin gene in insect cells. In addition, the pag1 promoter can be expressed more prominently as a short promoter. The pag1 promoter can also be expressed in transient transfected and permanently transfected cells. Further, the pag1 promoter can also be expressed when it is inserted into other viruses, such as Autographa californica nuclear polyhedrosis virus. The pag1 promoter has also been shown to express foreign genes strongly, such as in lacZ and luciferase. pag1 is driven by a constitutively expressed early type promoter, thus facilitating expression much earlier than the polyhedrin gene promoter.