Identification of AcMNPV EXON0 (ac141) domains required for efficient production of budded virus, dimerization and association with BV/ODV-C42 and FP25

The Autographa californica multiple nucleopolyhedrovirus (AcMNPV) late gene exon0 (ac141) is required for the efficient production of budded virus (BV). EXON0 interacts with nucleopcapsid protein BV/ODV-C42 and FP25 and enables egress of nucleocapsids from the nucleus to the cytoplasm. This study examines the functional domains of EXON0 that play a role in BV production. Six putative domains of the 261 amino acid EXON0 were deleted and examined for functionality by determining their ability to rescue an AcMNPV exon0 knockout bacmid. Domain mapping results showed that all the six domains were required but deletion of the N-terminal acidic region and the leucine zipper domains had the greatest impact on BV production. Yeast 2-hybrid and co-immunoprecipitation demonstrated that EXON0 formed dimers. Point mutation analysis demonstrated that the leucine zipper was required for dimer formation and interaction with BV/ODV-C42 and FP25. The charged domain was also required for BV/ODV-C42 interaction.