Abstract: Indirect ELISA was developed and applied for detection of serum antibodies against serotype 1(Yunnan strain)Riemerella anatipestifer (RA) in ducks, using ultrasonic RA as the coating antigen. Dilution method shew the optimum HRP-Goat Anti-Duck IgG dilution was 1∶3500, chessboard test shew the optimum coating antigen concentration was 2.7 mg/mL,the optimum dilution of serum samples was 1∶300 and the cut-off value of negative serum was 0.381.The interruption test shew the reactions between antiserum of serotype 1 RA and the coating antigen could be interrupted by specific type 1 RA, but could not be interruped by E.coli serotype O78 and serotype O132 strains(no cross-reaction).Repetition test shew the variant coefficients of the D value within assay and between assays less than 0.246 and 0.889 respectively. An interruption test and repetition test showed that the ELISA assay had good specificity and reproducibility to detect serum antibodies against serotype 1 RA in ducks.

Key words: Riemerella anatipestifer; ELISA; serum antibody; ELISA titer