title: Epizootiology and transmission of a newly discovered baculovirus from the mosquitoes Culex nigripalpus and C. quinquefasciatus.
abstract: Reports of mosquito baculoviruses are extremely uncommon and epizootics in field populations are rarely observed. We describe a baculovirus that was responsible for repeated and extended epizootics in field populations of Culex nigripalpus and C. quinquefasciatus over a 2 year period. These mosquito species are important vectors of St Louis and Eastern equine encephalitis in the United States. Our initial attempts to transmit this baculovirus to mosquitoes in the laboratory were unsuccessful. A salt mixture similar to that found in water supporting infection in the field was used in laboratory bioassays and indicated that certain salts were crucial to transmission of the virus. Further investigations revealed conclusively that transmission is mediated by divalent cations: magnesium is essential, whereas calcium inhibits virus transmission. These findings represent a major advancement in our understanding of the transmission of baculoviruses in mosquitoes and will allow characterization of the virus in the laboratory. In addition, they can explain, in great part, conditions that support epizootics in natural populations of mosquitoes that vector life-threatening diseases of man and animals.
authors.affiliation: US Department of Agriculture, Agriculture Research Service, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL 32604, USA1.
authors.forename: James J
authors.initials: JJ
authors.lastname: Becnel
authors.affiliation: US Department of Agriculture, Agriculture Research Service, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL 32604, USA1.
authors.forename: Susan E
authors.initials: SE
authors.lastname: White
authors.affiliation: US Department of Agriculture, Agriculture Research Service, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL 32604, USA1.
authors.forename: Bettina A
authors.initials: BA
authors.lastname: Moser
authors.affiliation: US Department of Agriculture, Agriculture Research Service, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL 32604, USA1.
authors.forename: Tokuo
authors.initials: T
authors.lastname: Fukuda
authors.affiliation: US Department of Agriculture, Agriculture Research Service, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL 32604, USA1.
authors.forename: Margaret J
authors.initials: MJ
authors.lastname: Rotstein
authors.affiliation: US Department of Agriculture, Agriculture Research Service, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL 32604, USA1.
authors.forename: Albert H
authors.initials: AH
authors.lastname: Undeen
authors.affiliation: West Virginia University, Morgantown, WV 26506, USA2.
authors.forename: Andrew
authors.initials: A
authors.lastname: Cockburn
mesh_terms: D000818:Animals; D016367:Baculoviridae / Q000187:drug effects / Q000302:isolation & purification* / Q000502:physiology / Q000648:ultrastructure; D002118:Calcium / Q000494:pharmacology; D002413:Cations, Divalent / Q000494:pharmacology; D003465:Culex / Q000187:drug effects / Q000648:ultrastructure / Q000821:virology*; D005618:Fresh Water / Q000821:virology; D007814:Larva / Q000187:drug effects / Q000648:ultrastructure / Q000821:virology; D008274:Magnesium / Q000494:pharmacology; D008854:Microscopy, Electron; D013552:Swine; D014865:Waste Disposal, Fluid
chemical_list: D002413:Cations, Divalent; D008274:Magnesium; D002118:Calcium