title: Interactions Within Susceptible Hosts Drive Establishment of Genetically Distinct Variants of an Insect-Borne Pathogen.
abstract: Coinfections are common, leading to pathogen interactions during transmission and establishment in a host. However, few studies have tested the relative strengths of pathogen interactions in vectors and hosts that determine the outcome of infection. We tested interactions between two genetically distinct variants of the mealybug-transmitted Grapevine leafroll-associated virus 3. The transmission efficiency of each variant in single variant inoculations by two vector species was determined. The effects of vector species, a coinfected source, and simultaneous inoculation from multiple hosts to one host on variant establishment were examined. Within-vector interactions could have a role in transmission from hosts containing mixed infections, but not when vectors were moved from separate singly infected source plants to a single recipient plant. The invasive Planococcus ficus (Signoret) was a more efficient vector than Pseudococcus viburni (Signoret). Transmission efficiency of the two variants did not differ in single variant inoculations. Overall infections were the same whether from singly or coinfected source plants. In mixed inoculations, establishment of one variant was reduced. Mixed inoculations from two singly infected source plants resulted in fewer mixed infections than expected by chance. Therefore, the observed outcome was determined subsequent to host inoculation rather than in the vector. The outcome may be due to resource competition between pathogens. Alternatively apparent competition may be responsible; the pathogens' differential ability to overcome host defenses and colonize the host may determine the final outcome of new infections. Detailed knowledge of interactions between pathogens during transmission and establishment could improve understanding and management of disease spread.
authors.affiliation: Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720.
authors.forename: G K
authors.initials: GK
authors.lastname: Blaisdell
authors.affiliation: Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720.
authors.forename: S
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720.
authors.forename: J R
authors.initials: JR
authors.lastname: Bratburd
authors.affiliation: Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720.
authors.forename: K M
authors.initials: KM
authors.lastname: Daane
authors.affiliation: Division of Agriculture and Natural Resources, University of California, UC Cooperative Extension, 1710 Soscol Ave., Suite 4, Napa, CA 94559.
authors.forename: M L
authors.initials: ML
authors.lastname: Cooper
authors.affiliation: Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720. rodrigoalmeida@berkeley.edu.
authors.forename: R P P
authors.initials: RP
authors.lastname: Almeida
mesh_terms: D000818:Animals; D002140:California; D029381:Closteroviridae / Q000235:genetics / Q000502:physiology*; D006430:Hemiptera / Q000821:virology*; D007303:Insect Vectors / Q000821:virology*; D058865:Introduced Species; D010935:Plant Diseases / Q000821:virology*; D013045:Species Specificity; D027843:Vitis / Q000821:virology*
keywords: Grapevine leafroll-associated virus 3; Planococcus ficus; Pseudococcus viburni; apparent competition; resource competition