Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/12/2006
Publication Date: 12/5/2006
Citation: Elliott, M.K. 2006. Bovine Papillomatous Digital Dermatitis-associated Spirochetes vary in Pathogenicity and Antigenic Cross-reactivity [abstract]. Proceedings of the 87th Annual Conference of Research Workers in Animal Diseases. p. 154.
Technical Abstract: Papillomatous digital dermatitis (PDD), also known as hairy heel wart, is a growing cause of lameness of cows in the U.S. dairy industry resulting in economic loss due to treatment costs, decreased milk production, lower reproductive efficiency and premature culling. Previous work using lesion material from a dairy farm in Iowa resulted in the isolation of four different Treponema phagedenis-like spirochetes (1A, 3A, 4A and 5B). Due to the lack of a good bovine model for PDD, in vivo virulence of, and antibody response to these PDD isolates was evaluated using a mouse abscess model. T. denticola and T. phagedenis were utilized as virulent and non-virulent controls respectively. Formalin-killed spirochetes served as a negative control for each isolate. Lesion development and antibody response were measured. Lesion size and total IgG produced were dose dependent for all groups. Isolate 1A produced significantly larger abscesses than other isolates. Isolate 3A induced skin necrosis by d2 resulting in open lesions by d7. Mixed infections (containing all 4 isolates together) produced a smaller mean lesion than infections containing a single isolate, with skin necrosis and open lesions similar to 3A. Antibody cross-reactivity between isolates varied while the antibody response produced to the mixed infection was skewed toward 5B and 1A. Antibodies to 5B and 3A cross-reacted with T. phagedenis. No isolates induced production of antibodies that cross-reacted with T. denticola. These data show that spirochetes isolated from PDD lesions have differential virulence and antigenic traits in vivo that may contribute to lesion development in PDD and evasion of the bovine immune response. Further investigation of these properties is important for the elucidation of virulence mechanisms and antigenic targets for vaccine development.