Diagnosis of footrot in goats: application of ELISA tests for response to antigens of Dichelobacter nodosus.
Goats are an important natural host for footrot and are infected with Dichelobacter nodosus that have virulence characteristics similar to those of sheep strains. However, the humoral response of goats to D. nodosus antigens and the possibility of a serological diagnosis of footrot in goats have not been studied. With the aim of evaluating a diagnostic ELISA test, we investigated the primary immune response of goats to experimental and natural infection, the memory response in recovered animals, and the transfer and persistence of colostral antibodies in kids. Footrot stimulated the goat's immune system and, as in sheep, under-running lesions were the primary stimulus for production of anti-D. nodosus antibodies. The immune response could be detected in ELISA using either fimbrial or outer membrane protein (KSCN) antigens of D. nodosus. Antibody titres resulting from infection declined quickly after recovery and reached pre-infection levels within 3-4 months. Previously affected animals, however, mounted a memory response when injected with purified D. nodosus antigens. Antibody levels attained after anamnestic challenge were correlated with the maximum levels attained during infection, and were therefore indicative of the infection status. Anti-D. nodosus antibodies were also transferred to kids via colostrum, but these antibodies did not persist and therefore were unlikely to interfere with the diagnostic ELISA after 3 months of age. Though these ELISA tests were highly specific, their sensitivity was rather low. Therefore, they are only suitable for a herd diagnosis of footrot in goats and are dependent on the development of advanced under-running infections in a proportion of affected goats.
Ghimire
S C
SC
Faculty of Veterinary Science, University of Sydney, Camden, NSW 2570, Australia. shiva_ghimire@hotmail.com
Whittington
R J
RJ
Dhungyel
O P
OP
Joshi
H D
HD
Egerton
J R
JR
D000818:Animals; D000831:Animals, Newborn; D000907:Antibodies, Bacterial / Q000097:blood; D000942:Antigens, Bacterial / Q000276:immunology*; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology; D020376:Dichelobacter nodosus / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000662:veterinary; D005260:Female; D010861:Fimbriae, Bacterial / Q000276:immunology; D005535:Foot Rot / Q000175:diagnosis / Q000276:immunology* / Q000382:microbiology; D015511:Goat Diseases / Q000175:diagnosis / Q000276:immunology* / Q000382:microbiology; D006041:Goats; D016905:Gram-Negative Bacterial Infections / Q000175:diagnosis / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D007112:Immunity, Maternally-Acquired / Q000276:immunology; D007156:Immunologic Memory / Q000276:immunology*; D011247:Pregnancy; D011897:Random Allocation; D012680:Sensitivity and Specificity
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins