title: Serological response of foals to polyvalent and monovalent live-attenuated African horse sickness virus vaccines.
abstract: African horse sickness (AHS) is typically a highly fatal disease in susceptible horses and vaccination is currently used to prevent the occurrence of disease in endemic areas. Similarly, vaccination has been central to the control of incursions of African horse sickness virus (AHSV) into previously unaffected areas and will likely play a significant role in any future incursions. Horses in the AHSV-infected area in South Africa are vaccinated annually with a live-attenuated (modified-live virus [MLV]) vaccine, which includes a cocktail of serotypes 1, 3, 4 (bottle 1) and 2, 6-8 (bottle 2) delivered in two separate doses at least 21 days apart. In this study, the neutralising antibody response of foals immunized with this polyvalent MLV AHSV vaccine was evaluated and compared to the response elicited to monovalent MLV AHSV serotypes. Naïve foals were immunized with either the polyvalent MLV AHSV vaccine, or a combination of monovalent MLV vaccines containing individual AHSV serotypes 1, 4, 7 or 8. There was a marked and consistent difference in the immunogenicity of individual virus serotypes contained in the MLV vaccines. Specifically, foals most consistently seroconverted to AHSV-1 and responses to other serotypes were highly variable, and often weak or not detected. The serotype-specific responses of foals given the monovalent MLV vaccines were similar to those of foals given the polyvalent MLV preparation suggesting that there is no obvious enhanced immune response through the administration of a monovalent vaccine as opposed to the polyvalent vaccine.
authors.affiliation: Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, Gauteng, South Africa. Electronic address: jannie.crafford@up.ac.za.
authors.forename: J E
authors.initials: JE
authors.lastname: Crafford
authors.affiliation: Equine Research Centre, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, Gauteng, South Africa.
authors.forename: C W
authors.initials: CW
authors.lastname: Lourens
authors.affiliation: Onderstepoort Biological Products SOC Ltd., Private Bag X07, Onderstepoort 0110, Gauteng, South Africa. Electronic address: theresa@obpvaccines.co.za.
authors.forename: T K
authors.initials: TK
authors.lastname: Smit
authors.affiliation: Department of Health Management, University of Prince Edward Island Atlantic Veterinary College, Charlottetown, PE, Canada C1A 4P3. Electronic address: iagardner@upei.ca.
authors.forename: I A
authors.initials: IA
authors.lastname: Gardner
authors.affiliation: Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, Gauteng, South Africa; Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, 5325 VetMed 3A, Davis, CA 95616, USA. Electronic address: njmaclachlan@ucdavis.edu.
authors.forename: N J
authors.initials: NJ
authors.lastname: MacLachlan
authors.affiliation: Equine Research Centre, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, Gauteng, South Africa. Electronic address: alan.guthrie@up.ac.za.
authors.forename: A J
authors.initials: AJ
authors.lastname: Guthrie
mesh_terms: D000355:African Horse Sickness / Q000517:prevention & control*; D000356:African Horse Sickness Virus / Q000145:classification; D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood*; D006736:Horses / Q000276:immunology*; D056724:Immunity, Humoral; D009500:Neutralization Tests; D011897:Random Allocation; D012703:Serotyping; D013019:South Africa; D014613:Vaccines, Attenuated / Q000276:immunology / Q000627:therapeutic use; D014765:Viral Vaccines / Q000276:immunology / Q000627:therapeutic use*
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D014613:Vaccines, Attenuated; D014765:Viral Vaccines
keywords: African horse sickness virus; Modified-live virus vaccine; Neutralizing antibody; Vaccination