A, The reactivity of rBdRAP-1 in ELISA with pre-immune (PI) sera and experimentally B. divergens-infected sera from cows (n = 6). All infected bovine sera showed higher OD values than non-infected sera in a dilution-dependant manner at all dilutions. B, The reactivity of rBdRAP-1 in ELISA with pre-immune (PI) sera and experimentally B. divergens-infected sera from gerbils (n = 5). Four of the five gerbil sera showed s higher OD values than non-infected sera in a dilution-dependant manner at dilutions 1∶200 to 1∶6,400. One gerbil serum (G5) showed no reactivity. At dilutions 1∶12,800 and 1∶26,600, there is no difference in the reactivity of the gerbil sera and the pre-immune sera. C, Specificity for the animal serum against recombinant BdRAP-1 was confirmed independently by immunoblotting. Four of the six bovine sera and two of the three gerbil sera reacted strongly against rBdRAP-1. One gerbil sera (G3) reacted weakly. Sera which showed the greatest reactivity in ELISA (C3, G1 and G4) also showed greatest reactivity on the blots. Sera G2 and G3 showed moderate reactivity in ELISA but surprisingly very low reactivity in the Western analysis. Sera which did not show any significant reactivity in the ELISA (C5,C6 and G5) also did not react against rBdRAP-1 by immune-blotting.