title: Viral Dose and Immunosuppression Modulate the Progression of Acute BVDV-1 Infection in Calves: Evidence of Long Term Persistence after Intra-Nasal Infection.
abstract: Bovine viral diarrhoea virus (BVDV) infection of cattle causes a diverse range of clinical outcomes from being asymptomatic, or a transient mild disease, to producing severe cases of acute disease leading to death. Four groups of calves were challenged with a type 1 BVDV strain, originating from a severe outbreak of BVDV in England, to study the effect of viral dose and immunosuppression on the viral replication and transmission of BVDV. Three groups received increasing amounts of virus: Group A received 10(2.55)TCID50/ml, group B 10(5.25)TCID50/ml and group C 10(6.7)TCID 50/ml. A fourth group (D) was inoculated with a medium dose (10(5.25)TCID50/ml) and concomitantly treated with dexamethasone (DMS) to assess the effects of chemically induced immunosuppression. Naïve calves were added as sentinel animals to assess virus transmission. The outcome of infection was dose dependent with animals given a higher dose developing severe disease and more pronounced viral replication. Despite virus being shed by the low-dose infection group, BVD was not transmitted to sentinel calves. Administration of dexamethasone (DMS) resulted in more severe clinical signs, prolonged viraemia and virus shedding. Using PCR techniques, viral RNA was detected in blood, several weeks after the limit of infectious virus recovery. Finally, a recently developed strand-specific RT-PCR detected negative strand viral RNA, indicative of actively replicating virus, in blood samples from convalescent animals, as late as 85 days post inoculation. This detection of long term replicating virus may indicate the way in which the virus persists and/or is reintroduced within herds.
authors.affiliation: Virology Department, Animal Health and Veterinary Laboratories Agency (AHVLA), Addlestone, United Kingdom.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Strong
authors.affiliation: Virology Department, Animal Health and Veterinary Laboratories Agency (AHVLA), Addlestone, United Kingdom.
authors.forename: Severina Anna
authors.initials: SA
authors.lastname: La Rocca
authors.affiliation: Virology Department, Animal Health and Veterinary Laboratories Agency (AHVLA), Addlestone, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Paton
authors.affiliation: Virology Department, Animal Health and Veterinary Laboratories Agency (AHVLA), Addlestone, United Kingdom.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Bensaude
authors.affiliation: Virology Department, Animal Health and Veterinary Laboratories Agency (AHVLA), Addlestone, United Kingdom.
authors.forename: Torstein
authors.initials: T
authors.lastname: Sandvik
authors.affiliation: Virology Department, Animal Health and Veterinary Laboratories Agency (AHVLA), Addlestone, United Kingdom.
authors.forename: Leanne
authors.initials: L
authors.lastname: Davis
authors.affiliation: Virology Department, Animal Health and Veterinary Laboratories Agency (AHVLA), Addlestone, United Kingdom.
authors.forename: Jane
authors.initials: J
authors.lastname: Turner
authors.affiliation: Virology Department, Animal Health and Veterinary Laboratories Agency (AHVLA), Addlestone, United Kingdom.
authors.forename: Trevor
authors.initials: T
authors.lastname: Drew
authors.affiliation: Veterinary Medicine Research & Development, Zoetis, Belgium.
authors.forename: Rudiger
authors.initials: R
authors.lastname: Raue
authors.affiliation: Veterinary Medicine Research & Development, Zoetis, Belgium.
authors.forename: Ilse
authors.initials: I
authors.lastname: Vangeel
authors.affiliation: Virology Department, Animal Health and Veterinary Laboratories Agency (AHVLA), Addlestone, United Kingdom.
authors.forename: Falko
authors.initials: F
authors.lastname: Steinbach
mesh_terms: D000281:Administration, Intranasal; D000818:Animals; D001831:Body Temperature; D001912:Bovine Virus Diarrhea-Mucosal Disease / Q000276:immunology* / Q000473:pathology / Q000821:virology*; D002417:Cattle; D003907:Dexamethasone / Q000494:pharmacology; D030241:Diarrhea Virus 1, Bovine Viral / Q000276:immunology*; D018450:Disease Progression; D004306:Dose-Response Relationship, Immunologic; D007165:Immunosuppression Therapy; D007958:Leukocyte Count; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D003907:Dexamethasone