title: Experimental Infection of Calves by Two Genetically-Distinct Strains of Rift Valley Fever Virus.
abstract: Recent outbreaks of Rift Valley fever in ruminant livestock, characterized by mass abortion and high mortality rates in neonates, have raised international interest in improving vaccine control strategies. Previously, we developed a reliable challenge model for sheep that improves the evaluation of existing and novel vaccines in sheep. This sheep model demonstrated differences in the pathogenesis of Rift Valley fever virus (RVFV) infection between two genetically-distinct wild-type strains of the virus, Saudi Arabia 2001 (SA01) and Kenya 2006 (Ken06). Here, we evaluated the pathogenicity of these two RVFV strains in mixed breed beef calves. There was a transient increase in rectal temperatures with both virus strains, but this clinical sign was less consistent than previously reported with sheep. Three of the five Ken06-infected animals had an early-onset viremia, one day post-infection (dpi), with viremia lasting at least three days. The same number of SA01-infected animals developed viremia at 2 dpi, but it only persisted through 3 dpi in one animal. The average virus titer for the SA01-infected calves was 1.6 logs less than for the Ken06-infected calves. Calves, inoculated with either strain, seroconverted by 5 dpi and showed time-dependent increases in their virus-neutralizing antibody titers. Consistent with the results obtained in the previous sheep study, elevated liver enzyme levels, more severe liver pathology and higher virus titers occurred with the Ken06 strain as compared to the SA01 strain. These results demonstrate the establishment of a virulent challenge model for vaccine evaluation in calves.
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Arthropod Borne Animal Disease Research Unit, 1515 College Ave., Manhattan, KS 66502, USA. William.Wilson@ars.usda.gov.
authors.forename: William C
authors.initials: WC
authors.lastname: Wilson
authors.affiliation: Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66502, USA. asally@vet.k-state.edu.
authors.forename: A Sally
authors.initials: AS
authors.lastname: Davis
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Arthropod Borne Animal Disease Research Unit, 1515 College Ave., Manhattan, KS 66502, USA. nng5757@vet.k-state.edu.|Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66502, USA. nng5757@vet.k-state.edu.
authors.forename: Natasha N
authors.initials: NN
authors.lastname: Gaudreault
authors.affiliation: Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66502, USA. bfaburay@vet.k-state.edu.
authors.forename: Bonto
authors.initials: B
authors.lastname: Faburay
authors.affiliation: Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66502, USA. jdtrujillo@vet.k-state.edu.
authors.forename: Jessie D
authors.initials: JD
authors.lastname: Trujillo
authors.affiliation: Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66502, USA. vinays@vet.k-state.edu.
authors.forename: Vinay
authors.initials: V
authors.lastname: Shivanna
authors.affiliation: Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66502, USA. sunwoo@ksu.edu.
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Sunwoo
authors.affiliation: Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66502, USA. balogh@vet.k-state.edu.
authors.forename: Aaron
authors.initials: A
authors.lastname: Balogh
authors.affiliation: Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66502, USA. adendale@vet.k-state.edu.
authors.forename: Abaineh
authors.initials: A
authors.lastname: Endalew
authors.affiliation: Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66502, USA. wma@vet.k-state.edu.
authors.forename: Wenjun
authors.initials: W
authors.lastname: Ma
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Arthropod Borne Animal Disease Research Unit, 1515 College Ave., Manhattan, KS 66502, USA. Barbara.Drolet@ars.usda.gov.
authors.forename: Barbara S
authors.initials: BS
authors.lastname: Drolet
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Arthropod Borne Animal Disease Research Unit, 1515 College Ave., Manhattan, KS 66502, USA. mgruder@uga.edu.|Southeastern Cooperative Wildlife Disease Study, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA. mgruder@uga.edu.
authors.forename: Mark G
authors.initials: MG
authors.lastname: Ruder
authors.affiliation: Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66502, USA. imorozov@vet.k-state.edu.
authors.forename: Igor
authors.initials: I
authors.lastname: Morozov
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Arthropod Borne Animal Disease Research Unit, 1515 College Ave., Manhattan, KS 66502, USA. Scott.McVey@ars.usda.gov.
authors.forename: D Scott
authors.initials: DS
authors.lastname: McVey
authors.affiliation: Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66502, USA. jricht@ksu.edu.
authors.forename: Juergen A
authors.initials: JA
authors.lastname: Richt
mesh_terms: D032761:Animal Experimentation; D000818:Animals; D000831:Animals, Newborn; D002417:Cattle; D002418:Cattle Diseases / Q000473:pathology* / Q000821:virology*; D004798:Enzymes / Q000097:blood; D005838:Genotype; D008099:Liver / Q000473:pathology; D012295:Rift Valley Fever / Q000473:pathology* / Q000821:virology*; D012296:Rift Valley fever virus / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity*; D013997:Time Factors; D019562:Viral Load; D014766:Viremia / Q000473:pathology / Q000821:virology
chemical_list: D004798:Enzymes
keywords: Cattle; Challenge model; Rift Valley fever; Rift Valley fever virus; pathogenicity