title: Experimental infection of fox squirrels (Sciurus niger) with West Nile virus.
abstract: Tree squirrels (Sciurus spp.) have exhibited high seroprevalence rates, suggesting that they are commonly exposed to West Nile virus (WNV). Many characteristics of WNV infections in tree squirrels, such as the durations and levels of viremia, remain unknown. To better understand WNV infections in fox squirrels (S. niger), we subcutaneously inoculated fourteen fox squirrels with WNV. Peak viremias ranged from 10(4.00) plaque-forming units (PFU)/mL of serum on day 2 post-infection (DPI) to 10(4.98) PFU/mL on 3 DPI, although viremias varied between individuals. Oral secretions of some fox squirrels were positive for WNV viral RNA, occasionally to moderate levels (10(3.2) PFU equivalent/swab). WNV PFU equivalents in organs were low or undetectable on 12 DPI; gross and histologic lesions were rare. The viremia profiles of fox squirrels indicate that they could serve as amplifying hosts in nature. In addition, viral RNA in the oral cavity and feces indicate that this species could contribute to alternative WNV transmission in suburban communities.
authors.affiliation: United States Department of Agriculture, Wildlife Services, National Wildlife Research Center, Fort Collins, CO 80521, USA. jeff.root@aphis.usda.gov
authors.forename: J Jeffrey
authors.initials: JJ
authors.lastname: Root
authors.forename: Paul T
authors.initials: PT
authors.lastname: Oesterle
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Nemeth
authors.forename: Kaci
authors.initials: K
authors.lastname: Klenk
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Gould
authors.forename: Robert G
authors.initials: RG
authors.lastname: McLean
authors.forename: Larry
authors.initials: L
authors.lastname: Clark
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Hall
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis / Q000097:blood; D001921:Brain / Q000473:pathology; D005260:Female; D007668:Kidney / Q000473:pathology; D008099:Liver / Q000473:pathology; D008297:Male; D009206:Myocardium / Q000473:pathology; D012367:RNA, Viral / Q000032:analysis; D011897:Random Allocation; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D012376:Rodent Diseases / Q000401:mortality / Q000473:pathology / Q000821:virology*; D012589:Sciuridae / Q000821:virology*; D014766:Viremia / Q000662:veterinary / Q000821:virology; D017201:Virus Shedding; D014901:West Nile Fever / Q000401:mortality / Q000473:pathology / Q000662:veterinary*; D014902:West Nile virus / Q000276:immunology / Q000472:pathogenicity / Q000502:physiology*
chemical_list: D000914:Antibodies, Viral; D012367:RNA, Viral