Vaccination of ducks with recombinant outer membrane protein (OmpA) and a 41 kDa partial protein (P45N′) of Riemerella anatipestifer

The generation of protective immunity against Riemerella anatipestifer infection in ducks were investigated by immunizations with recombinant glutathione sulfatransferase (GST) fusion's proteins of OmpA, a 42 kDa major outer membrane protein, and P45N', a 41 kDa N-terminal fragment of a newly identified 45 kDa potential surface protein from R. anatipestifer. The DNA encoding OmpA and P45N' were isolated from R. anatipestifer serotype 15 (field strain 110/89) and serotype 19 (reference strain 30/90), respectively. Immunoblotting and ELISA results showed that the purified recombinant proteins induced the production of antibodies in immunized ducks. However, neither was protective against subsequent challenge with the virulent serotype 15 strain, 34/90. All the five ducks immunized with formalinized R. anatipestiferstrain 34/90 survived the challenge with the homologous strain whereas six out of seven ducks in the non-immunized control group died within a week following the challenge. (C) 2002 Elsevier Science B.V. All rights reserved.