FIG. 6.

Activation of human TLR9 and chicken TLR21 by Campylobacter. HEK293 cells expressing human TLR9 (A) or HeLa 57A cells expressing chicken TLR21 (B) were stimulated with 30 μg of purified chromosomal DNA ml⁻¹ from C. jejuni strain 81116, GB18, or RM1221 or C. coli strain H1 for 5 h. Cells transfected with control vector were stimulated simultaneously to ensure TLR-specific NF-κB activation. ODN 2006 (0.5 μM) was used as positive control. None of the chromosomal Campylobacter DNA significantly activated TLR9. In contrast, DNA from all Campylobacter strains induced significant NF-κB activation in TLR21-transfected HEK 293 cells (P < 0.05). Values are the percent induction of NF-κB activation after stimulation with the positive control and are means ± the SEM of three independent experiments.