Characterization of core-oligosaccharide- and O-polysaccharide-specific monoclonal antibodies against Aeromonas salmonicida LPS binding to typical and atypical Aeromonas salmonicida isolates

Abstract

Monoclonal antibodies (mAbs) directed against Aeromonas salmonicida ssp. salmonicida (A +/F 216.1/83) lipopolysaccharide (LPS) were produced and characterized. The mAbs 4E8 and 10F4 recognized periodate-resistant epitope(s) on the O-polysaccharide ( O-PS) chains, while mAbs 3G3, 2G11, and 7C4 reacted with periodate-sensitive epitopes(s) on the core-oligosacchride (core-OS) region of LPS detected by ELISA and immunoblotting. The mAb 7F5 bound to O-PS epitope(s), too, but the recognized epitope(s) are partly periodate-resistant and partly periodate-sensitive. The three core-OS- and the three O-PS-specific mAbs recognized epitopes of LPS from all tested ten typical and five atypical A. salmonicida isolates when assayed by ELISA or immunoblotting, whereas only the three O-PS-specific mAbs reacted in a dot blot assay. All the O-PS- and the core-OS-specific mAbs bound to the high-molecular sugar component H 2 detected in the LPS fractions of all the A. salmonicida isolates used (SDS-PAGE and immunoblotting). Consequently, these H 2-components contain core-OS- and O-PS-epitopes. Using the O-PS-specific mAbs, no reaction was obtained with LPS from bacterial culture supernatants or whole cell lysates of two A. hydrophila isolates (ELISA, immunoblotting, dot blotting). However, the core-OS-specific mAbs reacted with A. hydrophila LPS (ELISA, immunoblotting), while dot blot studies did not result in binding of those mAbs to the bacterial cells. The described A. salmonicida LPS-specific mAbs with O-PS- and core-OS-specificity represent valuable tools for using in serodiagnosis or research.