title: Incorporation of GP64 into Helicoverpa armigera nucleopolyhedrovirus enhances virus infectivity in vivo and in vitro.
abstract: The envelope fusion proteins of baculoviruses, glycoprotein GP64 from group I nucleopolyhedrovirus (NPV) or the F protein from group II NPV and granulovirus, are essential for baculovirus morphogenesis and infectivity. The F protein is considered the ancestral baculovirus envelope fusion protein, while GP64 is a more recent evolutionary introduction into baculoviruses and exhibits higher fusogenic activity than the F protein. Each of the fusion proteins is required by the respective virus to spread infection within larval tissues. A recombinant Helicoverpa armigera NPV (HearNPV) expressing GP64 from Autographa californica multiple nucleopolyhedrovirus, vHaBac-gp64-egfp, was constructed, which still retained the native F protein, and its infectivity was assayed in vivo and in vitro. Analyses by one-step growth curve to determine viral titre and by quantitative PCR to determine viral DNA copy number showed that vHaBac-gp64-egfp was more infectious in vitro than the control, vHaBac-egfp. The polyhedrin gene (polh) was reintroduced into the recombinant viruses and bioassays showed that vHaBac-gp64-polh accelerated the mortality of infected larvae compared with the vHaBac-egfp-polh control, and the LC(50) (median lethal concentration) of vHaBac-gp64-polh was reduced to approximately 20 % of that of vHaBac-egfp-polh. Therefore, incorporation of GP64 into HearNPV budded virions improved virus infectivity both in vivo and in vitro. The construction of this bivalent virus with a more efficient fusion protein could improve the use of baculoviruses in different areas such as gene therapy and biocontrol.
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR 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 430071, PR China.
authors.forename: Yinyin
authors.initials: Y
authors.lastname: Gan
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR 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 430071, PR 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 430071, PR 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 430071, PR China.
authors.forename: Fei
authors.initials: F
authors.lastname: Deng
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005814:Genes, Viral; D007915:Lepidoptera / Q000821:virology*; D008561:Membrane Fusion / Q000235:genetics / Q000502:physiology; D017924:Nucleopolyhedroviruses / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology*; D000077183:Occlusion Body Matrix Proteins; D014760:Viral Fusion Proteins / Q000235:genetics / Q000502:physiology*; D015678:Viral Structural Proteins / Q000235:genetics / Q000502:physiology; D014774:Virulence / Q000235:genetics / Q000502:physiology; D053586:Virus Internalization; D014779:Virus Replication / Q000235:genetics / Q000502:physiology
chemical_list: D000077183:Occlusion Body Matrix Proteins; D014760:Viral Fusion Proteins; D015678:Viral Structural Proteins; C009829:polyhedrin protein, Nucleopolyhedrovirus