title: Efficiency of inactivated vaccines against heartwater in Burkina Faso: impact of Ehrlichia ruminantium genetic diversity.
abstract: In order to identify the appropriate strains to use in vaccination trials against heartwater in Burkina Faso, the protective effect of Gardel and Welgevonden strains was assessed against local strains on sheep vaccinated by infection-and-treatment method: Gardel protected significantly against Burkina Faso strains tested (survival rate 59% for immunised sheep vs 13% for control sheep) while Welgevonden did not (survival rate 45% for immunised sheep vs 25% for control sheep). The efficacy of the ISA50 inactivated vaccine, produced under industrial process, was evaluated in sheep during field challenges in two successive years. During year 1, there was a limited protective effect of the Gardel vaccine with 65% of survival rate for the vaccinated group compared to 49% for the control group (N=153, p=0.053). During year 2, the vaccine containing Gardel and a local strain gave an increased protective effect compared to the first trial: 72% of the vaccinated animals survived compared to 47% of the naïve animals (N=173, p<0.001). There was an important genetic diversity of strains in the field with detection of 11 different map1 genotypes in brains from control and vaccinated sheep post mortem. Map1 genotyping of strains detected in brains from control sheep showed that genotype distribution varied according to time and study areas, which could explain the difference in efficacy of the vaccine.
authors.affiliation: CIRDES (Centre International de Recherche-Développement sur l'Elevage en zone Sub-humide), BP 454, Bobo-Dioulasso 01, Burkina Faso.
authors.forename: Hassane
authors.initials: H
authors.lastname: Adakal
authors.forename: Frédéric
authors.initials: F
authors.lastname: Stachurski
authors.forename: Maurice
authors.initials: M
authors.lastname: Konkobo
authors.forename: Sébastien
authors.initials: S
authors.lastname: Zoungrana
authors.forename: Damien F
authors.initials: DF
authors.lastname: Meyer
authors.forename: Valérie
authors.initials: V
authors.lastname: Pinarello
authors.forename: Rosalie
authors.initials: R
authors.lastname: Aprelon
authors.forename: Isabel
authors.initials: I
authors.lastname: Marcelino
authors.forename: Paula M
authors.initials: PM
authors.lastname: Alves
authors.forename: Dominique
authors.initials: D
authors.lastname: Martinez
authors.forename: Thierry
authors.initials: T
authors.lastname: Lefrancois
authors.forename: Nathalie
authors.initials: N
authors.lastname: Vachiéry
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology; D015373:Bacterial Typing Techniques; D001428:Bacterial Vaccines / Q000276:immunology*; D002050:Burkina Faso; D056738:Cross Protection; D016995:Ehrlichia ruminantium / Q000145:classification / Q000235:genetics* / Q000276:immunology; D014644:Genetic Variation; D005838:Genotype; D006357:Heartwater Disease / Q000276:immunology / Q000517:prevention & control*; D012756:Sheep / Q000276:immunology / Q000382:microbiology; D012757:Sheep Diseases / Q000276:immunology / Q000517:prevention & control*; D013987:Ticks; D015164:Vaccines, Inactivated / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D001428:Bacterial Vaccines; D015164:Vaccines, Inactivated