Detection of brucella specific protein-A reactive antibodies in buffaloes by dot-enzyme-linked immunosorbent assay

Chand, P.; Batra, H.V.; Sadana, J.R.

Veterinary Record 122(7): 162-163

1988


ISSN/ISBN: 0042-4900
PMID: 3131948
Document Number: 317349
A dot-enzyme-linked immunosorbent assay (dot-ELISA) was performed using antigen-coated pre-blocked dipsticks prepared with 300 ng sonicated antigen (Brucella abortus S99). They were incubated in serum at 37 degrees C and then in protein-A-horse radish peroxidase conjugate before immersion in substrate solution. A positive reaction was indicated by the development of a brown dot within one minute. When serum samples from 16 aborted buffaloes were tested by a serum-agglutination test (SAT), a complement fixation test (CFT) and the dot-ELISA, 5 buffaloes were positive by SAT and CFT and had high dot-ELISA titres. B. abortus biotype 3 was isolated from the fetus of 2 of these buffaloes. When 68 serum samples from apparently normal in-contact buffaloes were tested 10 had SAT titres ( 1:10), 8 had positive CFT titres (1:8 to 1:256) but only 5 samples with positive SAT and CFT titres had positive dot-ELISA titres. It appeared that IgG1 and IgM were detected by SAT and CFT but that in dot-ELISA only protein-A reactive brucella specific antibodies were detected. This was confirmed when absorption of the protein-A antibodies was carried out with Staphylococcus aureus Cowan-I cells on pooled buffalo sera. The SAT, CFT and dot-ELISA titres were 1:320, 1:256 and 1:3200, respectively before absorption. The dot-ELISA titre fell to 1:25 after absorption but the SAT and CFT titres were unaltered.

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