CHARACTERIZATION OF A TYPE-IV PILUS PRODUCED BY AEROMONAS-CAVIAE

A pilus produced by a clinical isolate of Aeromanas caviae (strain CA1 95) was purified and partially characterised. The Mr of the pilin was estimated to be 23 kDa by SDS-PAGE. Its N-terminal amino-acid sequence showed that it was closely related to `bundle-forming' type IV pili p urified from other Aeromonas spp. associated with gastro-enteritis and considered to be important intestinal colonisation factors. Bundle-fo rming pili, often with a polar location, were seen on the surface of s train CA195 which was highly adherent to HEp-2 cells. Removal of surfa ce structures by mechanical means decreased adhesion (by greater than or equal to 50%) suggesting that these pili played some role in HEp-2 cell binding. This pilus type could prove an important marker for ente ropathogenic A. caviae which appear to lack other putative virulence f actors.