Vaccine containing a campylobacter bacterium having an enhanced antigenic property

A vaccine comprising a Campylobacter bacterium having an enhanced antigenic property, or an immunogenic fragment of said Campylobacter bacterium, which is harvested from a culture of a Campylobacter species grown in vitro in a culture medium with a combination of conditions comprising:

• (a) about 0.05% to about 3% bile or about 0.025% to about 0.6% of one or more bile acids or salts thereof;
• (b) at a temperature between about 30.degree. C. and about 42.degree. C.;
• (c) in air or a gas mixture, wherein the gas mixture comprises (i) about 5% to about 20% CO.sub.2 with about 80% to about 95% air;
• or (ii) about 5% to about 10% O.sub.2 with about 10% to about 20% CO.sub.2 with about 70% to about 85% N.sub.2 ;
• and
• (d) a divalent cation chelator selected from the group consisting of 0 to about 100 .mu.M of 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid/acetoxymethyl ester, 0 to about 10 mM of ethylene-bis(oxyethylenenitrilo)-tetraacetic acid, and 0 to about 100 .mu.M of ethylene-bis(oxyethylenenitrilo)-tetraacetic acid/acetoxymethyl ester,
• wherein said Campylobacter culture is in a growth phase at about early log phase, between early log phase and stationary phase, or at about stationary phase, and the enhanced antigenic property is a higher level of an immunogenic antigen when compared to the antigenic property of bacteria from a culture of the Campylobacter species grown in brain heart infusion broth.