title: Susceptibility of Ochlerotatus trivittatus (Coq.), Aedes albopictus (Skuse), and Culex pipiens (L.) to West Nile virus infection.
abstract: The susceptibility of Ochlerotatus trivittatus (Coq.) to West Nile virus (WNV) was assessed by comparing it to the susceptibility of Aedes albopictus (Skuse), a likely bridge vector, and Culex pipiens (L.), a primary WNV amplifying species. The three species were infected with WNV (NY crow-1999) by feeding on 2-3-day-old chickens with serum virus titers ranging from 10(2.5) to 10(9.5) cell culture infective dose (CID) 50s/mL. The lowest infective titer for Oc. trivittatus and Cx. pipiens was 10(4.5) CID50s/mL. Thirteen percent (4/32) and 2% (1/45) of each species became infected postprandially. Infection rates of the two species increased to 43% (6/14) and 15% (6/40) after blood meals with a titer of 10(5.5) CID50s/mL. In contrast no infection was observed in nine Ae. albopictus that fed among three chickens with titers of 10(4.5) CID50s/mL nor in 41 Ae. albopictus that fed among three chickens with titers of 10(5.0) CID50s/mL. The infective dose 50s for Oc. trivittatus, Cx. pipiens and Ae. albopictus were 10(6.0), 10(6.2), and 10(6.6) CID50s/mL, respectively. Collectively these observations suggest that Oc. trivittatus and Cx. pipiens are more susceptible than Ae. albopictus to WNV when they feed on hosts with WNV titers of <10(7.5) CID50s/mL, but nearly as susceptible with blood meal titers of > or =10(7.5) CID50s/mL. Unpublished studies in our laboratory showed that cottontail rabbits fed on by WNV-infected Oc. trivittatus developed viremias as high as 10(5.5) CID50s/mL serum which exceeds 10 (4.2 (3.4-4.6)) CID50s/mL, the predicted ID10+/-95% CI of Oc. trivittatus. Consequently this mosquito, which also feeds on humans and birds has the potential to serve as a bridge vector and as a maintenance vector among mammals.
authors.affiliation: Department of Entomology, College of Agriculture, Iowa State University, Ames, Iowa 50014, USA.
authors.forename: Sonthaya
authors.initials: S
authors.lastname: Tiawsirisup
authors.forename: Kenneth B
authors.initials: KB
authors.lastname: Platt
authors.forename: Richard B
authors.initials: RB
authors.lastname: Evans
authors.forename: Wayne A
authors.initials: WA
authors.lastname: Rowley
mesh_terms: D000330:Aedes / Q000145:classification / Q000276:immunology / Q000821:virology*; D000818:Animals; D002645:Chickens; D003465:Culex / Q000145:classification / Q000276:immunology / Q000821:virology*; D004198:Disease Susceptibility / Q000662:veterinary; D044969:Ochlerotatus / Q000276:immunology / Q000821:virology*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D013045:Species Specificity; D019562:Viral Load / Q000662:veterinary; D014901:West Nile Fever / Q000635:transmission*; D014902:West Nile virus / Q000235:genetics / Q000302:isolation & purification*