title: Genome sequence, prevalence and quantification of the first iflavirus identified in a phytoplasma insect vector.
abstract: The leafhopper Euscelidius variegatus is a natural vector of chrysanthemum yellows phytoplasma (CY) and an efficient vector of flavescence dorée phytoplasma (FD) under laboratory conditions. During a transcriptome sequencing (RNA-seq) project aimed at investigating the interactions between the insect and the two phytoplasmas, a 10,616-nucleotide-long contig with high sequence similarity to known picorna-like viruses was identified among the assembled insect transcripts. The discovery came totally unexpected, because insects from the laboratory colony did not show any evident symptom that could be related to the presence of a virus. The amino acid sequence, the shape and size of viral particles, and the results of phylogenetic analysis suggest that this virus, named Euscelidius variegatus virus 1 (EVV-1), can be considered a new member of a new species in the genus Iflavirus. EVV-1 was detected in all of the tested insects from the laboratory colony used for RNA-seq, both in phytoplasma-exposed and in non-exposed insects, but the viral load measured in FD-exposed samples was significantly lower than that in non-exposed insects. This result suggests the possible existence of an intriguing cross-talk among insects, endogenous bacteria, and viruses. The identification of two other E. variegatus laboratory colonies that were free of EVV-1 could represent the key to addressing some basic virological issues, e.g., viral replication and transmission mechanisms, and offer the opportunity to use infectious clones to express heterologous genes in the leafhopper and manipulate the expression of endogenous genes by promoting virus-induced gene silencing.
authors.affiliation: Institute for Sustainable Plant Protection, National Research Council of Italy, IPSP-CNR, Strada delle Cacce 73, 10135, Turin, Italy. simona.abba@ipsp.cnr.it.
authors.forename: Simona
authors.identifier: http://orcid.org/0000-0001-9345-5407
authors.initials: S
authors.lastname: Abbà
authors.affiliation: Institute for Sustainable Plant Protection, National Research Council of Italy, IPSP-CNR, Strada delle Cacce 73, 10135, Turin, Italy.
authors.forename: Luciana
authors.initials: L
authors.lastname: Galetto
authors.affiliation: Institute for Sustainable Plant Protection, National Research Council of Italy, IPSP-CNR, Strada delle Cacce 73, 10135, Turin, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Vallino
authors.affiliation: Institute for Sustainable Plant Protection, National Research Council of Italy, IPSP-CNR, Strada delle Cacce 73, 10135, Turin, Italy.
authors.forename: Marika
authors.initials: M
authors.lastname: Rossi
authors.affiliation: Institute for Sustainable Plant Protection, National Research Council of Italy, IPSP-CNR, Strada delle Cacce 73, 10135, Turin, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Turina
authors.affiliation: Department of Environmental Science, Policy and Management, University of California, 130 Mulford Hall, Berkeley, CA, 94720, USA.
authors.forename: Anne
authors.initials: A
authors.lastname: Sicard
authors.affiliation: Institute for Sustainable Plant Protection, National Research Council of Italy, IPSP-CNR, Strada delle Cacce 73, 10135, Turin, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Marzachì
mesh_terms: D000818:Animals; D001483:Base Sequence; D031202:Chrysanthemum / Q000382:microbiology / Q000821:virology*; D016679:Genome, Viral; D006430:Hemiptera / Q000382:microbiology / Q000821:virology*; D007303:Insect Vectors / Q000382:microbiology / Q000821:virology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D045582:Phytoplasma / Q000502:physiology*; D010849:Picornaviridae / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D010935:Plant Diseases / Q000821:virology*; D015995:Prevalence