Summary auto-generated
This study investigated whether Chlamydia trachomatis serovar K can establish persistent infection in human peripheral blood monocytes (PBMo). While C. trachomatis failed to replicate productively in PBMo—contrasting with productive infection in epithelial HEp-2 cells—the bacteria persisted intracellularly in a non-productive state. Using immunofluorescence, enzyme immunoassay, and RNA hybridization techniques, researchers detected three chlamydial components for up to 14 days post-infection: major outer-membrane protein (MOMP), lipopolysaccharide (LPS), and ribosomal RNA (rRNA). At higher multiplicity of infection (MOI 0.5 and 1), approximately 10% of initial MOMP, LPS, and rRNA levels remained detectable at day 14. The persistence of rRNA—which is typically degraded by cellular ribonucleases—suggests intact or partially intact bacterial organisms rather than merely resistant cell wall debris. The authors propose this intracellular persistence in monocytes may facilitate systemic dissemination of chlamydial antigens throughout the body via circulating immune cells, potentially explaining extra-genital manifestations such as reactive arthritis and Reiter's syndrome following urogenital chlamydial infection.
Key findings
- C. trachomatis serovar K established non-productive persistent infection in human monocytes, with no infectious progeny generated but bacterial components persisting for 14 days
- Chlamydial MOMP antigen, LPS, and rRNA remained detectable intracellularly at approximately 10% of initial levels by day 14 post-infection at higher MOI doses
- The persistence of fragile rRNA molecules in monocytes, despite cellular ribonuclease activity, indicates persistence of intact or largely intact bacterial organisms rather than just resistant cell wall remnants
- Monocyte-mediated persistence of chlamydial antigens may facilitate systemic distribution of bacteria through the bloodstream, potentially explaining systemic manifestations of urogenital chlamydial infections such as reactive arthritis
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Abstract
The replication of Chlamydia trachomatis serovar K was studied in human peripheral blood monocytes (PBMo). The intracellular fate of the bacteria was examined by determining the presence of chlamydial major outer-membrane protein (MOMP), lipopolysaccharide (LPS) and ribosomal RNA (rRNA). In-vitro infection of PBMo with C. trachomatis serovar K was not productive. However, chlamydial MOMP antigen, demonstrated by immunofluorescence, was present in PBMo for up to 14 days. Infected monocytes also contained chlamydial rRNA, measured by in-vitro hybridisation, and LPS, measured by enzyme immunoassay, for up to 14 days. These data are compatible with the hypothesis that the infection of PBMo with C. trachomatis may play a role in the systemic distribution of chlamydial antigens, leading to systemic manifestations of urogenital chlamydial infection.