Oral Presentation The Prato Conference on the Pathogenesis of Bacterial Infections of Animals 2016

Molecular mechanisms of pathogenesis in digital dermatitis in cattle and sheep - the role of treponemes (#35)

Stuart Carter 1 , Nicholas Evans
  1. School of Veterinary Science, University of Liverpool, Liverpool, UK., Liverpool, MERSEYSIDE, United Kingdom


Digital dermatitis (DD) is a serious lameness of bacterial aetiology which is endemic in dairy cattle in many countries and hence is a major welfare and economic issue on farms. Studies have clearly demonstrated a link with Treponema in DD lesions with 120 relevant isolates generated at Liverpool. Phylogeny indicates multiple Treponema species with a likely synergistic pathogenesis. We have recently demonstrated the disease is rapidly spreading and emerging in other farm animals, including beef cattle, sheep and goats and the causative treponemes are now identified in other disease manifestations in cattle, pigs and wild deer (elk). Transmission studies clearly indicate foot-to-foot as a main infection route although there is also possible transmission via the GI tract. We have recently identified specific dietary components capable of maintaining treponeme survival in vitro. The most effective antibiotics to control the treponemes are penicillin derivatives and macrolides; neither can be used in dairy cows. Also, the main treatments used to reduce DD incidence (toxic footbaths of formalin or copper sulphate or topical antibiotic treatment) are relatively ineffective and the majority soon to be banned. Consequently, there is a need to develop a vaccine. So, we have generated and mapped the genomes of the 3 main DD treponeme phylogroups and used reverse vaccinology to generate a panel (75) of recombinant treponeme surface proteins as potential vaccine candidates. Bioassay development has enabled the virulence of these proteins to be assessed and immunogenicity studies are underway. An MLST scheme for the 120 isolates has been developed (Clegg SR et al 2016) and shown that the organisms spreading through animal populations are largely the same. Hence, common DD treponeme vaccine targets should be achievable to control this disease.

Reference. Clegg SR et al (2016). doi:10.1128/AEM.00025-16

Review of DD (Carter/Evans). Vet J doi.org/10.1016/j.tvjl.2015.10.028