Detection of antibodies against Fusobacterium necrophorum and Porphyromonas levii-like species in dairy cattle with papillomatous digital dermatitis.

Bovine digital epidermitis involves different pathologies, including PDD, interdigital dermatitis, and foot rot. Bacteriological and molecular biological studies suggest that these are multimicrobial infections. During our study on the isolation of treponemes from biopsies of PDD, colonies producing black pigment were isolated frequently from the primary cultures, suggesting that Porphyromonas species were present. Moreover, 16S rRNA genes of Fusobacterium necrophorum and Porphyromonas levii-like species were detected in the lesions. We therefore determined whether an immunological response could be elicited by a P. levii-like organism isolated from a PDD lesion, as well as two subspecies of F. necrophorum in the sera from cows with and without PDD. A total of 151 serum samples were collected from 85 cows with PDD lesions and 33 cows without lesions on 12 PDD-positive farms and from 33 cows on two PDD-free farms. ELISA data showed that IgG antibody levels against antigens of P. levii-like species and F. necrophorum subsp. necrophorum were significantly higher in cows on PDD-positive farms than in cows on PDD-free farms, regardless of the presence of PDD lesions in the cows on the PDD-positive farms. However, F. necrophorum subsp. funduliforme was present at low levels in both groups. The ELISA results were confirmed by western blot analysis. Furthermore, antigens of these bacteria were detected in PDD-biopsy sections examined by immunohistochemical staining. F. necrophorum subsp. necrophorum and P. levii-like species may be involved in the pathogenesis of PDD.