Abstract: This experimentation was designed to help understand the antigenic and immunogenic rules of Aeromonas hydrophila (Ah). Indirect enzyme-linked immunosorbent assay showed the ratios of the antibody titers of the rabbit anti-ZN1-outer membrane protein (OMP) serum to the expression product, Mah-TrxA, and the recombinant protein of thioredoxin and a major adhesion agent and ZN1-OMP to be 1∶3 200 and 1∶12 800, respectively; and the ratios of the antibody titers of the rabbit anti- Mah-TrxA serum to Mah-TrxA and ZN1-OMP to be 1∶12 800 and 1∶1 600, respectively.Carp epithelial tumor cells (EPC) were used to study the adhesion effect of different sources and serotypes of Ah to EPC, as well as the biological functions played by Mah-TrxA.The adhesion test indicated that Ah were separated from the fish, the serotypes were O∶Ah10501, O∶9, and O∶CQ-1; the adhesion rate of Ah to EPC was greater than 97%; ATCC7966 was separated from milk, the serotype was O∶1; and, the adhesion rate of ATCC7966 to EPC was 78.5%.The results indicated that Mah-TrxA and the rabbit anti-Mah-TrxA serum could significantly inhibit or block the bacterial adhesion to EPC.It suggested that the fusion protein expressed through genetic engineering techniques in Ah had similar antigenicity and immunogenicity as the wild strain, ZN1.