Further, ΔfdhA and ΔhydB decreased potential for the CCI-779 invasion of the INT-407 cells was not as severe as that observed in the PIC (Figure 3a and b, Table 1). Collectively, our results suggest that under find more our experimental conditions the RPs contributed differentially to the virulent capabilities of C. jejuni. However, it should be noted that the use of in vitro systems in our experiment was meant only to assess the differential contribution of RPs to disparate niches and breakdown the role of these enzymes in cell adherence and invasion and intracellular survival.

Therefore, extrapolations of the results to the overall outcome of in vivo colonization should be constrained. For example, it was previously shown that ΔfdhA and ΔhydB were mildly impaired in the colonization of chickens, while ΔnapA and ΔnrfA were retrieved in significantly low numbers from this host Erastin ic50 [8, 10]. Further, the ΔmfrA was not deficient in the colonization of chickens [9]. Figure 3 The mutants’ interactions with PIC and INT-407 cells. The wildtype and mutant strains were added to the monolayers to achieve a multiplicity of infection (MOI) of 1:100, respectively. (a) Adherence and invasion of PIC. (b) Adherence, invasion, and intracellular survival in INT-407. Statistically significant (P < 0.05) differences are

highlighted with * and indicate comparisons with the wildtype. The experiment was repeated three times independently and samples were tested in duplicate per experiment. Data are presented as mean ± standard error. We further assessed the interactions Interleukin-3 receptor of the mutants with the eukaryotic monolayers using scanning electron microscopy as described elsewhere [31]. As reported

by Eucker and Konkel [32], our results show that the INT-407 cells exhibited a typical increase in surface ruffling (formation of a meshwork of appendages and filaments) after the addition of the bacteria as compared to the control (data not shown). However, there were no discernable differences in surface ruffling associated with the addition of the various mutants as compared to that of the wildtype. Surface ruffling was not readily apparent in our PIC and could not be clearly described. Further, while the bacterial cell shape of ΔnapA, ΔnrfA, and ΔmfrA did not appear different from that of the wildtype, both ΔfdhA (~ 60-70% of the observed cells) and ΔhydB (100% of cells) exhibited non-typical phenotypes as compared to the spiral shape of the wildtype cells. Specifically, ΔhydB formed elongated filaments that appeared to be made of multiple cells that failed in separation (Figure 4a and b, Table 1), which suggested that the mutant was defective in late cell division. Notably, a similar phenotype was associated with impaired Tat-dependent amidases of E. coli[33], which are essential for hydrolysis of septal peptidoglycan [33]. In C.