Isolation and purification of an outer membrane protein of Edwardsiella ictaluri and its antigenicity to channel catfish ( Ictalurus punctatus)

• Published in: Fish & shellfish immunology Vol. 3; no. 6; pp. 401 - 409
• Main Authors: Vinitnantharat, S., Plumb, J.A., Brown, A.E.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.1993
• Subjects: Edwardsiella ictaluri; fish immunology, bacteria, catfish; Freshwater; Ictalurus punctatus; fish immunology, bacteria, catfish
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1006/fsim.1993.1040

An outer membrane protein of Edwardsiella ictaluri was isolated, purified, partially characterised, and its antigenicity compared to that of crude preparations. Two major proteins, with apparent molecular mass of 36 and 18·5 kDa were detected in the cell extract preparations. After 30 passages of the bacterium on laboratory media, only the 36-kDa protein was still detectable on sodium dodecyl sulphate-polyacrylamide gels. Thirty-six, 42·5 and 18·5-kDa proteins were present in the purified outer membrane preparation of E. ictaluri, but only the 36-kDa was obtained in sufficient quantity to study further because the other two were lost after repetitive subcultivation of E. ictaluri. The immune response of channel catfish ( Ictalurus punctatus) to the purified outer membrane protein was significantly ( P>0·05) less than that produced by five-fold greater quantities of cell extract and crude membrane protein.