title: Infectivity of DWV associated to flower pollen: experimental evidence of a horizontal transmission route.
abstract: Deformed wing virus (DWV) is a honeybee pathogen whose presence is generally associated with infestation of the colony by the mite Varroa destructor, leading to the onset of infections responsible for the collapse of the bee colony. DWV contaminates bee products such as royal jelly, bee-bread and honey stored within the infected hive. Outside the hive, DWV has been found in pollen loads collected directly from infected as well as uninfected forager bees. It has been shown that the introduction of virus-contaminated pollen into a DWV-free hive results in the production of virus-contaminated food, whose role in the development of infected bees from virus-free eggs has been experimentally demonstrated. The aim of this study was twofold: (i) to ascertain the presence of DWV on pollen collected directly from flowers visited by honeybees and then quantify the viral load and (ii) determine whether the virus associated with pollen is infective. The results of our investigation provide evidence that DWV is present on pollen sampled directly from visited flowers and that, following injection in individuals belonging to the pollinator species Apis mellifera, it is able to establish an active infection, as indicated by the presence of replicating virus in the head of the injected bees. We also provide the first indication that the pollinator species Osmia cornuta is susceptible to DWV infection.
authors.affiliation: Department of Veterinary Science, Università of Pisa, Pisa, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Mazzei
authors.affiliation: Scuola Normale Superiore, Pisa, Italy.
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Carrozza
authors.affiliation: Department of Veterinary Science, Università of Pisa, Pisa, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Luisi
authors.affiliation: Department of Veterinary Science, Università of Pisa, Pisa, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Forzan
authors.affiliation: Department of Veterinary Science, Università of Pisa, Pisa, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Giusti
authors.affiliation: Department of Veterinary Science, Università of Pisa, Pisa, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Sagona
authors.affiliation: Department of Veterinary Science, Università of Pisa, Pisa, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Tolari
authors.affiliation: Department of Veterinary Science, Università of Pisa, Pisa, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Felicioli
mesh_terms: D000818:Animals; D001516:Bees / Q000235:genetics / Q000502:physiology / Q000821:virology*; D035264:Flowers / Q000235:genetics / Q000469:parasitology / Q000821:virology*; D022761:Gene Transfer, Horizontal; D006790:Host-Parasite Interactions; D054884:Host-Pathogen Interactions; D007304:Insect Viruses / Q000235:genetics / Q000502:physiology*; D011058:Pollen / Q000235:genetics / Q000469:parasitology / Q000821:virology*; D054817:Pollination; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019562:Viral Load / Q000235:genetics; D014779:Virus Replication / Q000235:genetics