Campylobacter jejuni is a major food born pathogen with approx. 214,000 reported cases in the EU in 2012. This microorganism has been the target of a number of biocontrol studies, some involving bacteriophages. Here we focus on the identification of factors that influence bacteriophage infection, and could therefore impact biocontrol. Through the generation of a series of monogenetic mutants based on the universal phage propagation strain C. jejuni NCTC12662 PT14, we have analysed the effects of Campylobacter surface structures and virulence related factors on bacteriophage infection. Phage replication assays indicated a potential role of the flagellin B gene product in the defense against infection by CP81-like bacteriophage CP_F1. Deactivation of the flaB gene increased the susceptibility of PT14 cultures to infection by CP_F1 in liquid media and resulted in clearer lysis in spot test assays. These observations were accompanied by an increase in free phage yields from liquid cultures. Further analyses revealed a two-fold increase in the bacteriophage adsorption constant during infection of the flaB mutant strain. Replication parameters for phage CP_F1 showed no changes in latent period but an almost 3-fold increase in burst-size, relative to the wild-type.
Although sharing an identity of 95% in amino acid composition with FlaA, motility analyses showed no reduction in swarming motility after flaB inactivation, in contrast to ΔflaA and ΔflaAB mutant strains, which showed a loss of motility function. These data suggest a role different than motility for FlaB, which may form the basis for a new mechanism of phage defense.