Plasmid-free Chlamydia trachomatis elicit lowered inflammation, delayed apoptosis, and reduced chemoattractant expression in HeLa cells compared to plasmid-containing wild type

Chlamydia trachomatis serovariants are responsible for either Trachoma, the leading cause of infectious blindness or sexually transmitted disease, wherein the endocervix is the most frequently infected site in women. Disease caused by Chlamydia typically involves chronic inflammation and scarring. Recent work with a live-attenuated A2497 plasmid deficient vaccine strain (A2497-) demonstrated protection in nonhuman primates against trachoma and a lack of measurable ocular pathology in A2497- infected monkeys. We therefore performed host cell transcriptome analysis of Hela cells infected with A2497 plasmid-containing (A2497) and A2497- Chlamydia over time. Our results indicate that relative to wild type A2497, the A2497- variant illicits a transcriptome response indicative of lowered inflammation response a delayed apoptosis response, a reduction in immune cell recruitement cytokine expression and a reduction in genes involved in cell proliferation and or fibrosis-like activities. The data provided here suggests a model that may explain how plasmid deficient chlamydia may provide an immuno-protective response without the pathology normally seen with plasmid-containing bacteria.

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Porcella SF, Carlson JH, Sturdevant DE, Sturdevant GL, Kanakabandi K, Virtaneva K, Wilder H, Whitmire WM, Song L, Caldwell HD