title: The FP25K Acts as a Negative Factor for the Infectivity of AcMNPV Budded Virus.
abstract: Baculoviruses generally produce two progeny phenotypes--the budded virus (BV) and the occlusion-derived virus (ODV)--and the intricate mechanisms that regulate the temporal synthesis of the two phenotypes are critical for the virus replication cycle, which are far from being clearly understood. FP25K was reported to be responsible for the regulation of BV/ODV, and the mutations within result in a decrease of normal ODVs formation and an increase of BVs production. In this study, we demonstrated that the increase of BV titer in an fp25k knockout recombinant (fp25k-negative) was a result of higher infectivity of BVs rather than an increased production of BVs. The constitution of the major structural proteins and genome of parental and fp25k-negative BVs were analyzed. The results showed that the integrity of the majority of DNA packaged into the fp25k-negative BVs was intact; i.e., the genomic DNA of fp25k-negative BV had better transformation and transfection efficiency than that of the parental virus, indicating more intact genomes in the virions. Although the analysis of proteins associated with BVs revealed that more envelope protein GP64 were incorporated into the fp25k-negative BVs, subsequent experiments suggested that overexpression of GP64 did not improve the titer of BVs. Thus, we conclude that the main reason for higher infectivity of BVs is due to better genome integrity, which benefits from the deletion of fp25k resulting in increased stability of the genome and produce a higher proportion of infectious BVs. FP25K acts as a negative factor for the infectivity of BV.
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, P.R. China.
authors.forename: Shufen
authors.initials: S
authors.lastname: Li
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, P.R. China.
authors.forename: Manli
authors.initials: M
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, P.R. China.
authors.forename: Shu
authors.initials: S
authors.lastname: Shen
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, P.R. China.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Hu
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, P.R. China.
authors.forename: Hualin
authors.initials: H
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, P.R. China.
authors.forename: Fei
authors.initials: F
authors.lastname: Deng
mesh_terms: D000818:Animals; D042003:DNA Packaging; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism; D015967:Gene Expression Regulation, Viral; D055786:Gene Knockout Techniques; D016679:Genome, Viral; D019590:Nucleocapsid Proteins / Q000235:genetics* / Q000378:metabolism; D017924:Nucleopolyhedroviruses / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity* / Q000648:ultrastructure; D061987:Sf9 Cells; D018411:Spodoptera; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism; D014771:Virion / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D014774:Virulence; D019065:Virus Assembly / Q000235:genetics; D014779:Virus Replication / Q000235:genetics
chemical_list: D004279:DNA, Viral; C121638:FP25K protein, Autographa californica nucleopolyhedrovirus; D019590:Nucleocapsid Proteins; D014759:Viral Envelope Proteins