title: Autographa californica multiple nucleopolyhedrovirus LEF-2 is a capsid protein required for amplification but not initiation of viral DNA replication.
abstract: The late expression factor 2 gene (lef-2) of baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV) has been identified as one of the factors essential for origin-dependent DNA replication in transient expression assays and has been shown to be involved in late/very late gene expression. To study the function of lef-2 in the life cycle of AcMNPV, lef-2 knockout and repair bacmids were generated by homologous recombination in Escherichia coli. Growth curve analysis showed that lef-2 was essential for virus production. Interestingly, a DNA replication assay indicated that lef-2 is not required for the initiation of viral DNA replication and that, rather, it is required for the amplification of DNA replication. lef-2 is also required for the expression of late and very late genes, as the expression of these genes was abolished by lef-2 deletion. Temporal and spatial distributions of LEF-2 protein in infected cells were also analyzed, and the data showed that LEF-2 protein was localized to the virogenic stroma in the nuclei of the infected cells. Analysis of purified virus particles revealed that LEF-2 is a viral protein component of both budded and occlusion-derived virions, predominantly in the nucleocapsids of the virus particles. This observation suggests that LEF-2 may be required immediately after virus entry into host cells for efficient viral DNA replication.
authors.affiliation: Department of Chemistry, National Tsing-Hua University, Hsinchu 300, Taiwan, Republic of China.
authors.forename: Carol P
authors.initials: CP
authors.lastname: Wu
authors.forename: Yi-Ju
authors.initials: YJ
authors.lastname: Huang
authors.forename: Jen-Yeu
authors.initials: JY
authors.lastname: Wang
authors.forename: Yueh-Lung
authors.initials: YL
authors.lastname: Wu
authors.forename: Huei-Ru
authors.initials: HR
authors.lastname: Lo
authors.forename: Jui-Ching
authors.initials: JC
authors.lastname: Wang
authors.forename: Yu-Chan
authors.initials: YC
authors.lastname: Chao
mesh_terms: D000818:Animals; D036022:Capsid Proteins / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D004279:DNA, Viral / Q000096:biosynthesis*; D017353:Gene Deletion; D015967:Gene Expression Regulation, Viral; D017924:Nucleopolyhedroviruses / Q000235:genetics / Q000502:physiology*; D018411:Spodoptera; D014779:Virus Replication
chemical_list: D036022:Capsid Proteins; D004279:DNA, Viral