Serological evidence of spirochaetal infections associated with digital dermatitis in dairy cattle

A potentially infectious aetiology for digital dermatitis in dairy cattle w as investigated and centred on the possible involvement of spirochaetes. Al enzyme-linked immunosorbent assay (ELISA) was developed to detect bovine a nti-Borrelia burgdorferi (B31) and anti-Treponeme (USA bovine isolates) ant ibodies in the sera of cows; sera were further tested for antigen specifici ty by Western blotting. Compared to normal cows, those with digital dermati tis had a much higher seropositivity rate to B. burgdorferi and the trepone mes. Significant correlations were shown between antibodies to B. burgdorfe ri and to Treponemes (P<0.001), suggesting strong cross-reacting epitopes s hared by these spirochaetes. In Western blotting of B. burgordferi antigens , the main band detected by ELISA positive sera was the 41kDa flagellar pro tein; lesser frequency of staining was seen with 34 (OspB), 39 and 55kDa ba nds. For the USA treponeme antigens, ELISA positive sera gave reactions to the 34-kDa band and also bands at 41 and 55kDa. Polyclonal antibodies to Tr eponema denticola and T. vincentii showed reactions with the bovine trepone mes which were predominantly to the 34-kDa antigen. Monoclonal antibodies t o B. burgdorferi flagella (41kDa) antigen and OspA (31kDa) did not detect a ny treponeme bands in Western blotting. The study has provided serological evidence that spirochaetes (which are related to human treponemes) may be i nvolved in the pathogenesis of digital dermatitis.