title: Immunisation of sheep against heartwater in The Gambia using inactivated and attenuated Ehrlichia ruminantium vaccines.
abstract: Heartwater (cowdriosis) is a disease of ruminants caused by a rickettsial pathogen Ehrlichia ruminantium and transmitted by ticks of the genus Amblyomma. The purpose of this work was to evaluate the protective efficacies of inactivated and attenuated vaccines to protect sheep against heartwater in The Gambia. An inactivated vaccine, prepared from E. ruminantium (Gardel stock), and a live attenuated vaccine from E. ruminantium (Senegal stock), were evaluated in two independent on-station trials. A local stock of E. ruminantium (Kerr Seringe) was used as challenge material. Inactivated and live attenuated vaccines provided 43% and 100% protection, respectively, against virulent needle challenge. In a subsequent field trial, the attenuated vaccine protected 75% of sheep against virulent tick challenge, which was fatal for all control sheep. Quantification by real-time PCR showed that an immunising dose of approximately 23,000 attenuated E. ruminantium organisms was sufficient. Moreover, restriction fragment length polymorphism (RFLP) analysis indicated that the local Kerr Seringe genotype caused mortality amongst control sheep, whereas fatalities in the vaccinated group could be attributed to a different genotype.
authors.affiliation: International Trypanotolerance Centre, PMB 14, Banjul, The Gambia. b.fabureh1@vet.uu.nl <b.fabureh1@vet.uu.nl>
authors.forename: Bonto
authors.initials: B
authors.lastname: Faburay
authors.forename: Dirk
authors.initials: D
authors.lastname: Geysen
authors.forename: Ansumana
authors.initials: A
authors.lastname: Ceesay
authors.forename: Isabel
authors.initials: I
authors.lastname: Marcelino
authors.forename: Paula M
authors.initials: PM
authors.lastname: Alves
authors.forename: Amar
authors.initials: A
authors.lastname: Taoufik
authors.forename: Milagros
authors.initials: M
authors.lastname: Postigo
authors.forename: Lesley
authors.initials: L
authors.lastname: Bell-Sakyi
authors.forename: Frans
authors.initials: F
authors.lastname: Jongejan
mesh_terms: D000818:Animals; D001428:Bacterial Vaccines / Q000235:genetics / Q000276:immunology*; D004269:DNA, Bacterial / Q000097:blood / Q000276:immunology; D016995:Ehrlichia ruminantium / Q000235:genetics / Q000276:immunology*; D005714:Gambia; D005838:Genotype; D006357:Heartwater Disease / Q000097:blood / Q000235:genetics / Q000276:immunology / Q000517:prevention & control*; D007114:Immunization; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012756:Sheep / Q000276:immunology* / Q000382:microbiology; D012757:Sheep Diseases / Q000097:blood / Q000235:genetics / Q000276:immunology / Q000517:prevention & control*; D014613:Vaccines, Attenuated / Q000235:genetics / Q000276:immunology
chemical_list: D001428:Bacterial Vaccines; D004269:DNA, Bacterial; D014613:Vaccines, Attenuated