Identification of a 43-kDa outer-membrane protein as an adhesin in Aeromonas caviae

Aeromonas spp, are associated with intestinal and extra-intestinal infectio ns. However, the virulence factors of A. caviae remain, for the most part, poorly known, This study examined the interactions involved in the adherenc e of A. caviae isolates Ae56, Ae391 and Ae398 to HEp-2 cells. All strains e xpressed high levels of aggregative adherence. Maximum adhesion occurred wi th bacteria grown at 22 degreesC, but transmission electron microscopy did not reveal the presence of fimbrial structures on the bacterial cell surfac e. Outer-membrane proteins (OMPs) extracted from isolate Ae398, grown at 22 degreesC and 37 degreesC, showed similar SDS-PAGE protein profiles. Most p roteins were < 60 kDa, A major 43-kDa protein was seen only in the boiled O MP extract. The biotinylated 43-kDa protein bound specifically to HEp-2 cel ls. Microbeads coated with the 43-kDa protein were also adherent to HEp-2 c ells, and anti-43-kDa protein antibody blocked adherence of 43-kDa protein- coated latex beads. These data suggest that the 43-kDa OMP functions as an adhesin in A. caviae.