Toll-Like Receptor 2 Activation by Chlamydia trachomatis Is Plasmid Dependent, and Plasmid-Responsive Chromosomal Loci Are Coordinately Regulated in Response to Glucose Limitation by C. trachomatis but Not by C. muridarum

Abstract

We previously demonstrated that plasmid-deficient Chlamydia muridarum retains the ability to infect the murine genital tract but does not elicit oviduct pathology because it fails to activate Toll-like receptor 2 (TLR2). We derived a plasmid-cured derivative of the human genital isolate Chlamydia trachomatis D/UW-3/Cx, strain CTD153, which also fails to activate TLR2, indicating this virulence phenotype is associated with plasmid loss in both C. trachomatis and C. muridarum. As observed with plasmid-deficient C. muridarum, CTD153 displayed impaired accumulation of glycogen within inclusions. Transcriptional profiling of the plasmid-deficient strains by using custom microarrays identified a conserved group of chromosomal loci, the expression of which was similarly controlled in plasmid-deficient C. muridarum strains CM972 and CM3.1 and plasmid-deficient C. trachomatis CTD153. However, although expression of glycogen synthase, encoded by glgA, was greatly reduced in CTD153, it was unaltered in plasmid-deficient C. muridarum strains. Thus, additional plasmid-associated factors are required for glycogen accumulation by this chlamydial species. Furthermore, in C. trachomatis, glgA and other plasmid-responsive chromosomal loci (PRCLs) were transcriptionally responsive to glucose limitation, indicating that additional regulatory elements may be involved in the coordinated expression of these candidate virulence effectors. Glucose-limited C. trachomatis displayed reduced TLR2 stimulation in an in vitro assay. During human chlamydial infection, glucose limitation may decrease chlamydial virulence through its effects on plasmid-responsive chromosomal genes.

Virulence determinants in the obligate intracellular pathogen Chlamydia trachomatis revealed by forward genetic approaches

“…2C). Glycogen is prominent in the lumen of inclusions of plasmid bearing Chlamydia strains (10,11), with extrabacterial glycogen likely arising as a result of spontaneous lysis of bacteria (12). In Grn mutants, extrabacterial glycogen forms large intrainclusion aggregates, as observed by transmission electron microscopy (Fig.…”

Plasmid deficiency in urogenital isolates ofChlamydia trachomatisreduces infectivity and virulence in a mouse model

“…Overall, studies of infection with both wild‐type and plasmid‐free C. trachomatis and C. muridarum strains in mouse urogenital infection indicate that the plasmid modulates infectivity and may be essential for pathogenic immune responses (O'Connell et al ., 2007; Carlson et al ., 2008; Olivares‐Zavaleta et al ., 2010; Russell et al ., 2011). It is all but certain that either C. muridarum plasmid gene products or products of plasmid responsive loci on the bacterial chromosome engage Toll‐like receptor‐2 (TLR‐2) causing deleterious responses in mouse urogenital infections with C. muridarum (O'Connell et al ., 2011). Similarly, in ocular infection of lower primates, plasmid‐free C. trachomatis was found to infect, but was significantly attenuated for inducing inflammatory responses (Kari et al ., 2011).…”

Emancipating Chlamydia: Advances in the Genetic Manipulation of a Recalcitrant Intracellular Pathogen

“…The plasmid carries eight ORFs and is required for the production of glycogen within the inclusion (57,65). In C. trachomatis, C. muridarum, and C. caviae, a plasmid is required for the expression of several virulence-associated chromosomal genes (23,(66)(67)(68). Plasmid loss is associated with reduced activation of Toll-like receptor 2 (TLR2)-dependent inflammatory responses, and plasmid-deficient C. trachomatis and C. muridarum strains have been used as live attenuated vaccine strains against genital and ocular infections (69)(70)(71).…”