An indirect ELISA for serodiagnosis of cattle footrot caused by Fusobacterium necrophorum

A serodiagnostic ELISA (rL-ELISA) using recombinant truncated leukotoxin protein PL2 (aa 311–644) of Fusobacterium necrophorum as antigen was developed for detection of antibodies against F. necrophorum from cattle footrot. In rL-ELISA, the recombinant diagnostic antigen showed no cross-reaction with antisera against bovine foot and mouth disease virus, bovine rhinotracheitis virus, bovine viral diarrhea virus, bovine rotavirus type A, bovine Escherichia coli, and bovine Salmonella. The rL-ELISA could confirm the existence of antibodies against F. necrophorum at day 7 after infection. Detection of the field samples indicated relative sensitivity of rL-ELISA to nL-ELISA using the purified native leukotoxin A as antigen was 96.43%, and relative specificity of rL-ELISA to nL-ELISA was 94.26%. These data demonstrated the rL-ELISA would have a potential use for early diagnosis of cattle footrot caused by F. necrophorum.