Variation of chemosensory receptor content of <it>Campylobacter jejuni</it> strains and modulation of receptor gene expression under different <it>in vivo</it> and <it>in vitro</it> growth conditions

<p>Abstract</p> <p>Background</p> <p>Chemotaxis is crucial for the colonisation/infection of hosts with <it>Campylobacter jejuni.</it> Central to chemotaxis are the group A chemotaxis genes that are responsible for sensing the external environment. The distribution of group A chemoreceptor genes, as found in the <it>C. jejuni</it> sequenced strains, <it>tlp1-4, 7, 10</it> and <it>11</it> were determined in 33 clinical human and avian isolates.</p> <p>Results</p> <p>Group A <it>tlp</it> gene content varied among the strains with genes encoding <it>tlp1</it> (aspartate receptor, <it>ccaA</it>) and <it>tlp7</it> present in all strains tested, where as <it>tlp11</it> was present in only one of our international collection clinical isolates, <it>C. jejuni</it> 520, but was more prevalent (9/13) in the freshly isolated clinical stains from patients who required hospitalisation due to <it>C. jejuni</it> infection (GCH1-17). Relative expression levels of the group A <it>tlp</it> genes were also determined in <it>C. jejuni</it> reference strains NCTC 11168-GS, 11168-O and 81116 using cells grown <it>in vitro</it> at 37°C, 42°C and maintained at room temperature and with cells isolated directly from murine and avian hosts by immune magnetic separation without subsequent culture. Gene expression of <it>tlp</it> genes was varied based on strain, growth conditions and <it>in vivo</it> isolation source. <it>Tlp1,</it> although the most conserved, showed the lowest and most varied mRNA expression and protein production under laboratory conditions. <it>Tlp7</it> was highly expressed at most conditions tested, and gene expression was not influenced by the <it>tlp7</it> gene encoding a full length protein or one expressed as separate periplasmic and cytoplasmic domains.</p> <p>Conclusion</p> <p>We have shown that chemosensory receptor set variation exists among <it>C. jejuni</it> strains, but is not dependent on the isolation source.</p>