Detection of Dichelobacter nodosus using species-specific oligonucleotides as PCR primers.

Dichelobacter nodosus is an essential causative agent of ovine footrot, a disease of major economic significance. Four oligonucleotides complementary to variable regions of the 16S rRNA of D. nodosus were identified, synthesized and tested for their specificity and sensitivity as probes for the detection of D. nodosus. In hybridization reactions using total RNA as the target nucleic acid, three probes were found to be both sensitive and species-specific. When these probes were used as primers in PCR reactions, on both purified D. nodosus DNA and whole cells, the sensitivity of detection was increased by several orders of magnitude. Using PCR, it was possible to detect the presence of D. nodosus by direct examination of lesion material from footrot infected sheep.