In vitro inhibition of epithelial cell invasion by Aeromonas hydrophila and Vibrio species by fish Aeromonas hydrophila major adhesin

摘要

A virulent strain of A. hydrophila (PPD 134/91) was obtained from the Primary Production Department, Singapore. Its major adhesin was isolated and purified by potassium thiocyanate extraction and Bio-Gel P-100 gel filtration. The ability of the protein in peak 1, termed major adhesin, to inhibit bacteria from adhering to and invading host cells was studied in vitro using epithelioma papillosum cells of carp (EPC). Results showed that a concentration of 10μg/ml of this major adhesin could competitively inhibit 28% of A. hydrophila PPD 134/91 from invading EPC cells in vitro. When the concentration was increased to 40μg/ml, the major adhesin significantly cross-inhibited 9 other virulent or weakly virulent strains of A. hydrophila. In addition, the major adhesin significantly inhibited not only another bacterial strain from the same family, A. sobria, but also strains of Vibrio spp. It is suggested that the major adhesin of this virulent A. hydrophila strain has the potential to be used as a vaccine against the heterogeneous Aeromonas and Vibrio species.