Characteristics of an avirulent Campylobacter jejuni strain and its virulence-enhanced variants.

The virulence of Campylobacter jejuni for 11-day-old chick embryos is associated with the ability to invade the chorio-allantoic membrane, to resist phagocytosis and to survive and proliferate in vivo. The pathogenicity of a well characterised avirulent C. jejuni strain was enhanced by passaging it intravenously and chorio-allantoically through chick embryos. The resulting isogenic variants had greatly increased ability to survive in vivo. In this study, the morphological and cell-surface characteristics of the avirulent parental strain were compared with those of the more virulent variants to determine whether pathogenicity was associated with one or more cell-surface constituents. Changes associated with the increased virulence of the two variants included alterations in cultural and cellular morphology, loss of flagella, expression of a new outer-membrane protein, alterations in cell-surface carbohydrates and decreases in cell-surface hydrophobicity.