title: Autographa californica multiple nucleopolyhedrovirus ac66 is required for the efficient egress of nucleocapsids from the nucleus, general synthesis of preoccluded virions and occlusion body formation.
abstract: Although orf66 (ac66) of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is conserved in all sequenced lepidopteran baculovirus genomes, its function is not known. This paper describes generation of an ac66 knockout AcMNPV bacmid mutant and analyses of the influence of ac66 deletion on the virus replication in Sf-9 cells so as to determine the role of ac66 in the viral life cycle. Results indicated that budded virus (BV) yields were reduced over 99% in ac66-null mutant infected cells in comparison to that in wild-type virus infected cells. Optical microscopy revealed that occlusion body synthesis was significantly reduced in the ac66 knockout bacmid-transfected cells. In addition, ac66 deletion interrupted preoccluded virion synthesis. The mutant phenotype was rescued by an ac66 repair bacmid. On the other hand, real-time PCR analysis indicated that ac66 deletion did not affect the levels of viral DNA replication. Electron microscopy revealed that ac66 is not essential for nucleocapsid assembly, but for the efficient transport of nucleocapsids from the nucleus to the cytoplasm. These results suggested that ac66 plays an important role for the efficient exit of nucleocapsids from the nucleus to the cytoplasm for BV synthesis as well as for preoccluded virion and occlusion synthesis.
authors.affiliation: State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, 510275 Guangzhou, China. kejhkejh@yahoo.cn
authors.forename: Jianhao
authors.initials: J
authors.lastname: Ke
authors.forename: Jinwen
authors.initials: J
authors.lastname: Wang
authors.forename: Riqiang
authors.initials: R
authors.lastname: Deng
authors.forename: Xunzhang
authors.initials: X
authors.lastname: Wang
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured; D017353:Gene Deletion; D015967:Gene Expression Regulation, Viral; D007181:Inclusion Bodies, Viral / Q000378:metabolism*; D009036:Moths / Q000821:virology*; D019251:Nucleocapsid / Q000378:metabolism*; D017924:Nucleopolyhedroviruses / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D016366:Open Reading Frames / Q000235:genetics; D018411:Spodoptera / Q000821:virology; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014771:Virion / Q000378:metabolism*
chemical_list: D014764:Viral Proteins