title: Autographa californica multiple nucleopolyhedrovirus ac76 is involved in intranuclear microvesicle formation.
abstract: In this study, we characterized Autographa californica multiple nucleopolyhedrovirus (AcMNPV) orf76 (ac76), which is a highly conserved gene of unknown function in lepidopteran baculoviruses. Transcriptional analysis of ac76 revealed that transcription of multiple overlapping multicistronic transcripts initiates from a canonical TAAG late-transcription start motif but terminates at different 3' ends at 24 h postinfection in AcMNPV-infected Sf9 cells. To investigate the role of ac76 in the baculovirus life cycle, an ac76-knockout virus was constructed using an AcMNPV bacmid system. Microscopy, titration assays, and Western blot analysis demonstrated that the resulting ac76-knockout virus was unable to produce budded viruses. Quantitative real-time PCR analysis demonstrated that ac76 deletion did not affect viral DNA synthesis. Electron microscopy showed that virus-induced intranuclear microvesicles as well as occlusion-derived virions were never observed in cells transfected with the ac76-knockout virus. Confocal microscopy analysis revealed that Ac76 was predominantly localized to the ring zone of nuclei during the late phase of infection. This suggests that ac76 plays a role in intranuclear microvesicle formation. To the best of our knowledge, this is the first baculovirus gene identified to be involved in intranuclear microvesicle formation.
authors.affiliation: State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, China.
authors.forename: Zhaoyang
authors.initials: Z
authors.lastname: Hu
authors.forename: Meijin
authors.initials: M
authors.lastname: Yuan
authors.forename: Wenbi
authors.initials: W
authors.lastname: Wu
authors.forename: Chao
authors.initials: C
authors.lastname: Liu
authors.forename: Kai
authors.initials: K
authors.lastname: Yang
authors.forename: Yi
authors.initials: Y
authors.lastname: Pang
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002467:Cell Nucleus / Q000648:ultrastructure / Q000821:virology*; D004279:DNA, Viral / Q000096:biosynthesis; D055786:Gene Knockout Techniques; D007181:Inclusion Bodies, Viral / Q000648:ultrastructure; D007915:Lepidoptera / Q000821:virology*; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D017924:Nucleopolyhedroviruses / Q000502:physiology*; D016133:Polymerase Chain Reaction; D019562:Viral Load; D014764:Viral Proteins / Q000235:genetics / Q000502:physiology*; D014779:Virus Replication
chemical_list: D004279:DNA, Viral; D014764:Viral Proteins