Epidemiological studies into the role of serogroup-specific vaccines to control footrot in sheep

目前的建议，控制羊的蹄病包括接种疫苗。蹄病是由革兰氏阴性厌氧菌Dichelobacternodosus引起的，根据提供运动和粘附的菌毛基因的遗传变异，将其分为10个血清群; A-I和M。在英国，有一种市售和许可的口蹄疫疫苗，Footvax，含有9个血清群。抗原竞争意味着随着疫苗血清群数量的增加，疫苗的效力降低。已发表的同行评议的科学文献提供的证据表明，使用较少的D。在澳大利亚，最近采用的策略是希望接种疫苗的农场提交足部拭子样品以确定其群中存在的蹄病血清群。一旦建立，提供含有在该群中发现的单一血清群的疫苗。最多同时使用两种血清群疫苗。该项目的目的是确定是否有针对性的血清群疫苗接种是更有效的比市售疫苗在减少英国鸡群的蹄流行。更有效的疫苗接种策略将减少对抗生素治疗蹄病的依赖，并为羊的福利和农场盈利带来积极的结果。将设计并进行群内试验，以研究血清群特异性疫苗接种在具有两个或更多血清群的群中的有效性。拭子样本将用于分析接种血清群特异性和市售腐蹄病疫苗后结节杜氏杆菌载量和血清群的变化。将分析疫苗接种对鸡群跛行流行率、生产力、抗生素使用和随后盈利能力的影响。将估计国家一级抗生素使用的潜在减少。

Current recommendations for the control of footrot in sheep include vaccination.Footrot is caused by the Gram-negative anaerobe Dichelobacter nodosus which is classified into ten serogroups; A-I and M based on genetic variation in the fimbriae gene which provides motility and adhesion. There is one commercially available and licensed vaccine for footrot in the UK, Footvax, containing nine serogroups. Antigenic competition means that as the number of vaccine serogroups increases, the efficacy of the vaccine reduces. Published peer-reviewed scientific literature has provided evidence that using fewer serogroups of D. nodosus results in longer lasting protection and less clinical disease in comparison to the commercial vaccine.In Australia, a recently adopted strategy is for farms wishing to vaccinate to submit foot swab samples for determination of the footrot serogroups present in their flock. Once established, vaccine is provided containing a single serogroup found in that flock. Up to two serogroup vaccines are used concurrently. The aim of the project is to establish if targeted serogroup vaccination is more efficacious than the commercially available vaccine in reducing footrot prevalence in English flocks. A more effective vaccination strategy would lead to reduced reliance on antibiotics for the treatment of footrot, and a positive outcome for sheep welfare and farm profitability. Within flock trials will be designed and conducted to investigate the efficacy of serogroup specific vaccination in flocks with two or more serogroups. Swab samples will be used to analyse changes in D.nodosus load and serogroup following vaccination with serogroup specific and commercial footrot vaccine. The impact of vaccination on flock lameness prevalence, productivity, antibiotic use and subsequent profitability will be analysed. The potential reduction in antibiotic use at a national level will be estimated.