title: Partial functional rescue of Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus infectivity by replacement of F protein with GP64 from Autographa californica multicapsid nucleopolyhedrovirus.
abstract: Two distinct envelope fusion proteins (EFPs) (GP64 and F) have been identified in members of the Baculoviridae family of viruses. F proteins are found in group II nucleopolyhedroviruses (NPVs) of alphabaculoviruses and in beta- and deltabaculoviruses, while GP64 occurs only in group I NPVs of alphabaculoviruses. It was proposed that an ancestral baculovirus acquired the gp64 gene that conferred a selective advantage and allowed it to evolve into group I NPVs. The F protein is a functional analogue of GP64, as evidenced from the rescue of gp64-null Autographa californica multicapsid nucleopolyhedrovirus (MNPV) (AcMNPV) by F proteins from group II NPVs or from betabaculoviruses. However, GP64 failed to rescue an F-null Spodoptera exigua MNPV (SeMNPV) (group II NPV). Here, we report the successful generation of an infectious gp64-rescued group II NPV of Helicoverpa armigera (vHaBacΔF-gp64). Viral growth curve assays and quantitative real-time PCR (Q-PCR), however, showed substantially decreased infectivity of vHaBacΔF-gp64 compared to the HaF rescue control virus vHaBacΔF-HaF. Electron microscopy further showed that most vHaBacΔF-gp64 budded viruses (BV) in the cell culture supernatant lacked envelope components and contained morphologically aberrant nucleocapsids, suggesting the improper BV envelopment or budding of vHaBacΔF-gp64. Bioassays using pseudotyped viruses with a reintroduced polyhedrin gene showed that GP64-pseudotyped Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus (HearNPV) significantly delayed the mortality of infected H. armigera larvae.
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China.
authors.forename: Manli
authors.initials: M
authors.lastname: Wang
authors.forename: Feifei
authors.initials: F
authors.lastname: Yin
authors.forename: Shu
authors.initials: S
authors.lastname: Shen
authors.forename: Ying
authors.initials: Y
authors.lastname: Tan
authors.forename: Fei
authors.initials: F
authors.lastname: Deng
authors.forename: Just M
authors.initials: JM
authors.lastname: Vlak
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Hu
authors.forename: Hualin
authors.initials: H
authors.lastname: Wang
mesh_terms: D016367:Baculoviridae / Q000235:genetics; D005075:Biological Evolution; D019251:Nucleocapsid / Q000502:physiology*; D017924:Nucleopolyhedroviruses / Q000235:genetics / Q000472:pathogenicity*; D014760:Viral Fusion Proteins / Q000502:physiology*
chemical_list: D014760:Viral Fusion Proteins