title: Is nonviremic transmission of West Nile virus by Culex mosquitoes (Diptera: Culicidae) nonviremic?
abstract: Inter- and intraspecific transfer of West Nile virus (family Flaviviridae, genus Flavivirus, WNV) occurred infrequently when donor Culex tarsalis Coquillett fed concurrently on house finches with recipient Culex quinquefasciatus Say and Cx. tarsalis. Five of six of these house finches had WNV in blood samples collected by jugular venipuncture 30-45 min postfeeding, with titers ranging from 2.3 to 4.2 log10 plaque-forming units (PFU)/ml. After 2-wk incubation at 26 degrees C, three Cx. quinquefasciatus and one Cx. tarsalis of 230 blood-fed recipients were infected, of which one Cx. quinquefasciatus was capable of transmission. Our data indicated that infectious female mosquitoes feeding on small vertebrates create a nonpropagative viremia capable of infecting concurrently cofeeding females. The proportion of recipients infected is likely related to the amount of virus expectorated by donor females, the blood volume of the vertebrate host, and the susceptibility of the cofeeding mosquitoes.
authors.affiliation: Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA. arbo123@pacbell.net
authors.forename: William K
authors.initials: WK
authors.lastname: Reisen
authors.forename: Ying
authors.initials: Y
authors.lastname: Fang
authors.forename: Vincent
authors.initials: V
authors.lastname: Martinez
mesh_terms: D000818:Animals; D001715:Bird Diseases / Q000635:transmission* / Q000821:virology; D003465:Culex / Q000821:virology*; D005260:Female; D046369:Finches / Q000821:virology*; D007303:Insect Vectors / Q000821:virology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014766:Viremia / Q000635:transmission / Q000662:veterinary; D014901:West Nile Fever / Q000635:transmission* / Q000821:virology; D014902:West Nile virus / Q000302:isolation & purification / Q000472:pathogenicity*