title: A virulence factor encoded by a polydnavirus confers tolerance to transgenic tobacco plants against lepidopteran larvae, by impairing nutrient absorption.
abstract: The biological control of insect pests is based on the use of natural enemies. However, the growing information on the molecular mechanisms underpinning the interactions between insects and their natural antagonists can be exploited to develop "bio-inspired" pest control strategies, mimicking suppression mechanisms shaped by long co-evolutionary processes. Here we focus on a virulence factor encoded by the polydnavirus associated with the braconid wasp Toxoneuron nigriceps (TnBV), an endophagous parasitoid of noctuid moth larvae. This virulence factor (TnBVANK1) is a member of the viral ankyrin (ANK) protein family, and appears to be involved both in immunosuppression and endocrine alterations of the host. Transgenic tobacco plants expressing TnBVANK1 showed insecticide activity and caused developmental delay in Spodoptera littoralis larvae feeding on them. This effect was more evident in a transgenic line showing a higher number of transcripts of the viral gene. However, this effect was not associated with evidence of translocation into the haemocoel of the entire protein, where the receptors of TnBVANK1 are putatively located. Indeed, immunolocalization experiments evidenced the accumulation of this viral protein in the midgut, where it formed a thick layer coating the brush border of epithelial cells. In vitro transport experiments demonstrated that the presence of recombinant TnBVANK1 exerted a dose-dependent negative impact on amino acid transport. These results open new perspectives for insect control and stimulate additional research efforts to pursue the development of novel bioinsecticides, encoded by parasitoid-derived genes. However, future work will have to carefully evaluate any effect that these molecules may have on beneficial insects and on non-target organisms.
authors.affiliation: Dipartimento di Agraria, Università di Napoli "Federico II", Portici, Italy.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Di Lelio
authors.affiliation: Dipartimento di Agraria, Università di Napoli "Federico II", Portici, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Caccia
authors.affiliation: Dipartimento di Agraria, Università di Napoli "Federico II", Portici, Italy.
authors.forename: Mariangela
authors.initials: M
authors.lastname: Coppola
authors.affiliation: Istituto di Biostrutture e Bioimmagini (IBB), CNR, Napoli, Italy; Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Seconda Università di Napoli, Caserta, Italy.
authors.forename: Martina
authors.initials: M
authors.lastname: Buonanno
authors.affiliation: Dipartimento di Agraria, Università di Napoli "Federico II", Portici, Italy.
authors.forename: Gennaro
authors.initials: G
authors.lastname: Di Prisco
authors.affiliation: Dipartimento di Agraria, Università di Napoli "Federico II", Portici, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Varricchio
authors.affiliation: Dipartimento di Agraria, Università di Napoli "Federico II", Portici, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Franzetti
authors.affiliation: Dipartimento di Agraria, Università di Napoli "Federico II", Portici, Italy.
authors.forename: Giandomenico
authors.initials: G
authors.lastname: Corrado
authors.affiliation: Istituto di Biostrutture e Bioimmagini (IBB), CNR, Napoli, Italy.
authors.forename: Simona M
authors.initials: SM
authors.lastname: Monti
authors.affiliation: Dipartimento di Agraria, Università di Napoli "Federico II", Portici, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Rao
authors.affiliation: Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italy.
authors.forename: Morena
authors.initials: M
authors.lastname: Casartelli
authors.affiliation: Dipartimento di Agraria, Università di Napoli "Federico II", Portici, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Pennacchio
mesh_terms: D000818:Animals; D017487:Ankyrins / Q000235:genetics / Q000494:pharmacology*; D001120:Arginine / Q000378:metabolism; D002942:Circular Dichroism; D005822:Genetic Vectors / Q000008:administration & dosage; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva / Q000502:physiology; D007915:Lepidoptera / Q000196:embryology / Q000502:physiology*; D008969:Molecular Sequence Data; D030821:Plants, Genetically Modified / Q000254:growth & development* / Q000469:parasitology; D018071:Polydnaviridae / Q000235:genetics; D014026:Nicotiana / Q000235:genetics* / Q000254:growth & development / Q000469:parasitology; D014764:Viral Proteins / Q000235:genetics / Q000494:pharmacology; D037521:Virulence Factors / Q000235:genetics / Q000494:pharmacology*
chemical_list: D017487:Ankyrins; D007306:Insecticides; D014764:Viral Proteins; D037521:Virulence Factors; D001120:Arginine