Enzyme-linked immunosorbent assay for detecting antibodies in cattle in a herd in which anaplasmosis was diagnosed

Abstract

An enzyme-linked immunosorbent assay (ELISA) was developed for detecting antibodies in anaplasmosis with an antigen prepared from infected bovine erythrocytes. Protein A labeled with horseradish peroxidase was used as conjugate. A comparison was made of results of ELISA, complement fixation test (CFT), and card test (CT) on sera from 97 cows in a herd in which anaplasmosis had been diagnosed. Positive ELISA reactions were observed in serum dilutions of 1:20 or greater in each of 26 cows positive by CFT and in 18 of 2 cows suspected by CFT. Of 49 cows negative by CFT, 31 were negative by ELISA. Positive ELISA reactions were observed in 45 cows positive by CT; 27 of 44 cows negative by CT were negative by ELISA. No ELISA reactions were detected in the sera of 23 cows found negative in the CFT and CT or in 8 cows negative in CFT and positive in CT. No positive CFT, CT, or ELISA reactions were observed in sera of cattle in a noninfected herd.