title: A polydnavirus ANK protein acts as virulence factor by disrupting the function of prothoracic gland steroidogenic cells.
abstract: Polydnaviruses are obligate symbionts integrated as proviruses in the genome of some ichneumonoid wasps that parasitize lepidopteran larvae. Polydnavirus free viral particles, which are injected into the host at oviposition, express virulence factors that impair immunity and development. To date, most studies have focused on the molecular mechanisms underpinning immunosuppression, whereas how viral genes disrupt the endocrine balance remains largely uninvestigated. Using Drosophila as a model system, the present report analyzes the function of a member of the ankyrin gene family of the bracovirus associated with Toxoneuron nigriceps, a larval parasitoid of the noctuid moth Heliothis virescens. We found that the TnBVank1 expression in the Drosophila prothoracic gland blocks the larval-pupal molt. This phenotype can be rescued by feeding the larvae with 20-hydroxyecdysone. The localization of the TnBVANK1 is restricted to the cytoplasm where it interacts with Hrs and Alix marked endosomes. Collectively, our data demonstrate that the TnBVANK1 protein acts as a virulence factor that causes the disruption of ecdysone biosynthesis and developmental arrest by impairing the vesicular traffic of ecdysteroid precursors in the prothoracic gland steroidogenic cells.
authors.affiliation: Dipartimento di Farmacia e Biotecnologie, Università di Bologna, Bologna, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Valzania
authors.affiliation: Dipartimento di Farmacia e Biotecnologie, Università di Bologna, Bologna, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Romani
authors.affiliation: Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Tian
authors.affiliation: Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Li
authors.affiliation: Dipartimento di Farmacia e Biotecnologie, Università di Bologna, Bologna, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Cavaliere
authors.affiliation: Dipartimento di Agraria - Laboratorio di Entomologia "E. Tremblay", Università di Napoli 'Federico II', Portici (NA), Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Pennacchio
authors.affiliation: Dipartimento di Farmacia e Biotecnologie, Università di Bologna, Bologna, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Gargiulo
mesh_terms: D000818:Animals; D017487:Ankyrins / Q000235:genetics / Q000378:metabolism; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism / Q000821:virology; D004331:Drosophila melanogaster; D011992:Endosomes / Q000235:genetics / Q000378:metabolism / Q000821:virology; D009036:Moths / Q000235:genetics / Q000378:metabolism / Q000821:virology; D018071:Polydnaviridae / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D017487:Ankyrins; D014764:Viral Proteins; D037521:Virulence Factors
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