Baculoviruses are well known for their large, circular, dou-ble-stranded DNA genomes. The type member, AcMNPV, is the best characterized andundergoes a successionof early, late and very late gene expression during its infection cycle. The viral genes involved inDNAreplicationhave previously been identified and their products are required for the acti-vation of late gene expression. In this study, we FLAG- and HA-tagged the replication late expression factors of AcMNPV, examined their expression and functional activities by CAT assay and Western blot analysis, and determined their subcellular localization in transfected cells by subcellular fractionation and immunofluorescent microscopy