AN ENVIRONMENTALLY REGULATED PILUS-LIKE APPENDAGE INVOLVED IN CAMPYLOBACTER PATHOGENESIS

Examination of strains of Campylobacter jejuni, Campylobacter coli, an d Campylobacter fetus by electron microscopy revealed that they produc ed peritrichous pilus-like appendages when the bacteria were grown in the presence of bile salts. Various bile-salt supplements were used an d it was found that deoxycholate and chenodeoxycholic acid caused a si gnificant enhancement of pilus production and resulted in a highly agg regative phenotype. Morphologically, the pili were between 4 and 7 nm in width and were greater than 1 mu m in length. A gene, termed pspA, which encodes a predicted protein resembling protease IV of Escherichi a coil, was identified in C. jejuni strain 81-176. A site-specific ins ertional mutation within this gene resulted in the loss of pilus synth esis as determined by electron microscopy. Insertions upstream and dow nstream of the gene had no effect on pilus production. The non-piliate d mutant of strain 81-176 showed no reduction in adherence to or invas ion of INT 407 cells in vitro. However, this mutant, while still posse ssing the ability to colonize ferrets, caused significantly reduced di sease symptoms in this animal model.