TY - JOUR T1 - Synovial <em>Chlamydia trachomatis</em> up regulates expression of a panel of genes similar to that transcribed by <em>Mycobacterium tuberculosis</em> during persistent infection JF - Annals of the Rheumatic Diseases JO - Ann Rheum Dis SP - 321 LP - 327 DO - 10.1136/ard.2005.042226 VL - 65 IS - 3 AU - H C GĂ©rard AU - J A Whittum-Hudson AU - H R Schumacher AU - A P Hudson Y1 - 2006/03/01 UR - http://ard.bmj.com/content/65/3/321.abstract N2 - Background: Synovial tissues in patients with Chlamydia associated arthritis are persistently infected by C trachomatis, an organism for which genetic manipulation is not possible. M tuberculosis also engages in persistent infection, and because this bacterium is genetically tractable many groups have been able to define transcriptional characteristics of mycobacterial growth and persistence. Objective: To investigate whether the pattern of gene expression underlying chlamydial persistence is similar to that underlying mycobacterial persistence. Methods: 194 genes in M tuberculosis that are transcriptionally up regulated to support in vivo growth and persistence of that organism have previously been identified. Each of those genes was compared with the C trachomatis genome to identify orthologues. Expression of selected chlamydial orthologues so identified was assessed by real time RT-PCR in an in vitro model of chlamydial persistence and synovial tissues from patients who were PCR positive for C trachomatis at that site. Results: 67 C trachomatis genes were identified as being orthologous to mycobacterial persistence related genes, representing 35% of the genes tested. The chlamydial orthologues fell into similar metabolic and other categories as those in M tuberculosis. Expression of a majority of selected chlamydial orthologues was strongly up regulated in an in vitro model of chlamydial persistence and in synovial tissues of relevant patients, compared with their expression during active infection. Conclusions: These observations provide new insight into the molecular genetic basis underlying chlamydial persistence, and indicate that this information can be obtained, in some instances, by extrapolating observations made in other biological systems and/or organisms. ER -