Given that microbiota-depleted and LOS sensitized IL-10−/− mice did not develop campylobacteriosis upon infection with non-motile, flagella-deficient C. jejuni mutants [19], these mice were further used as a convenient model for studying C. jejuni virulence factors triggering acute campylobacteriosis [7], including proteases such as PepP [20] and HtrA [21,22]. Here, HTRA1 is linked to campylobacteriosis.