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Title: AN INDIRECT ENZYME-LINKED IMMUNOSORBENT ASSAY FOR THE DETECTION OF BRUCELLA MELITENSIS ANTIBODY IN GOAT MILK

Author
item FUNK, NATHAN - IA STATE UNIV., AMES, IA
item Tabatabai, Louisa
item ELZER, P - LA STATE UNIV., LOUISANA
item MARTIN, B - USDA/APHIS/NVSL, AMES, IA
item HOFFMAN, L - IA STATE UNIV., AMES, IA

Submitted to: Journal of Clinical Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/7/2004
Publication Date: 2/10/2005
Citation: Funk, N.D., Tabatabai, L.B., Elzer, P.H., Martin, B.M., Hoffman, L.J. 2005. An indirect enzyme-linked immunosorbent assay for the detection of Brucella melitensis antibody in goat milk. Journal of Clinical Microbiology. 43:721-725.

Interpretive Summary: Brucella melitensis is the cause of brucellosis in sheep and goats, often resulting in abortion. Although B. melitensis has been eradicated in goats and sheep within the United States since 1972, sporadic outbreaks have occurred primarily from contacts with imported goats that are infected. Continued surveillance of goat herds for brucellosis is imperative. The objective of this study was to develop a sensitive and specific indirect enzyme-linked immunoassay (ELISA) for the detection of B. melitensis antibody in goat milk. A previously described serum ELISA test developed for bovine brucellosis was adapted for bulk goat milk testing. Using artificial milk mixtures, the ELISA test was able to detect one high-titer animal in a herd of greater than 1600 animals and one low-titer animal in a herd of 50 animals. On the basis of this estimation, it was recommended that herds be sampled in groups of 50 animals or less for bulk milk testing. The ELISA test was found to be sensitive and specific and shows potential for use as a bulk milk test for the detection of B. melitensis antibody in goat milk.

Technical Abstract: Brucella melitensis is the cause of brucellosis in sheep and goats, often resulting in abortion. Few cases of B. melitensis infection in goats have occurred in the United States over the last 25 years. However, vigilance for brucellosis in goats must be maintained as it is in the bovine milk industry to ensure that it is not introduced into the U.S. goat population. The objective of this study was to develop a sensitive and specific indirect enzyme-linked immunoassay (iELISA) for the detection of B. melitensis antibody in goat milk. Brucella salt-extractable protein extract (BCSP) was employed as an antigen, and a horse-radish peroxidase labeled polyclonal anti-goat antibody was used as an anti-species conjugate. Thirteen of 13 (100%) individual positive milk samples tested positive, and 134 of 134 (100%) negative bulk milk samples tested negative by the iELISA developed. Three positive milk samples of high, medium, and low absorbance values were used in simulating one positive animal in a negative herd. By this estimation, one high titer animal could be detected in a herd of greater than 1600 animals. Estimations for medium and low titer animals were one positive animal in a herd of less than 200 and 50 animals, respectively. On the basis of this estimation, it is recommended that herds be sampled in groups of 50 animals or less for bulk milk testing. The iELISA developed was found to be sensitive and specific and shows potential for use as a bulk milk test for the detection of B. melitensis antibody in goat milk.