HAEMOPHILUS-DUCREYI ATTACHES TO AND INVADES HUMAN EPITHELIAL-CELLS IN-VITRO

Haemophilus ducreyi is a sexually transmitted pathogen that causes gen ital ulcers and inguinal adenopathy. Because chancroidal ulcers are mo st commonly located on the foreskins of uncircumcised males,,ve utiliz ed human foreskin epithelial cells (HFECs) to investigate the initial interaction of H. ducreyi with its host. The eight different strains o f H. ducreyi that were studied varied in their abilities to attach to these epithelial cells, with six strains consistently attaching to gre ater than or equal to 90% of HFECs and two strains attaching to < 25% of HFECs. The strains with low levels of adherence also failed to exhi bit chaining in broth culture and were avirulent in the rabbit model, suggesting that virulence in this model and attachment may be linked. The most adherent strain, LA228R, was further evaluated for its abilit y to invade HFECs and HEp-2 cells. Scanning electron microscopy and tr ansmission electron microscopy of HFECs after interaction with LA228R produced images consistent with attachment, ingestion into vesicles, a nd escape from the vesicles into the cytoplasm. In addition, the genta micin protection assay and inhibition of invasion by cytochalasin B an d D indicated that LA228R was able to invade both HFECs and HEp-2 cell s. Further examination of the mechanisms involved in the adherence and invasion of H. ducreyi into epithelial cells and their correlation wi th virulence will provide a better understanding of the pathogenesis o f the disease caused by this important pathogen.