Comparative Expression Profiling of the Chlamydia trachomatis pmp Gene Family for Clinical and Reference Strains

Abstract

Background Chlamydia trachomatis, an obligate intracellular pathogen, is a leading worldwide cause of ocular and urogenital diseases. Advances have been made in our understanding of the nine-member polymorphic membrane protein (Pmp) gene (pmp) family of C. trachomatis. However, there is only limited information on their biologic role, especially for biological variants (biovar) and clinical strains.Methodology/Principal FindingsWe evaluated expression for pmps throughout development for reference strains E/Bour and L2/434, representing different biovars, and for clinical E and L2 strains. Immunoreactivity of patient sera to recombinant (r)Pmps was also determined. All pmps were expressed at two hours. pmpA had the lowest expression but was up-regulated at 12 h for all strains, indicating involvement in reticulate body development. For pmpD, expression peaked at 36 h. Additionally, 57.7% of sera from infected and 0% from uninfected adolescents were reactive to rPmpD (p = 0.001), suggesting a role in immunogenicity. pmpF had the highest expression levels for all clinical strains and L2/434 with differential expression of the pmpFE operon for the same strains. Sera were nonreactive to rPmpF despite immunoreactivity to rMOMP and rPmpD, suggesting that PmpF is not associated with humoral immune responses. pmpFE sequences for clinical strains were identical to those of the respective reference strains. We identified the putative pmpFE promoter, which was, surprisingly, 100% conserved for all strains. Analyses of ribosomal binding sites, RNase E, and hairpin structures suggested complex regulatory mechanism(s) for this >6 Kb operon.Conclusions/SignificanceThe dissimilar expression of the same pmp for different C. trachomatis strains may explain different strain-specific needs and phenotypic distinctions. This is further supported by the differential immunoreactivity to rPmpD and rPmpF of sera from patients infected with different strains. Furthermore, clinical E strains did not correlate with the E reference strain at the gene expression level, reinforcing the need for expansive studies of clinical strains.

Immunoproteomic Discovery of Novel T Cell Antigens from the Obligate Intracellular PathogenChlamydia

“…This speculation is further supported by the finding that PmpF is the most polymorphic protein among all C. trachomatis Pmps (39). The identification of PmpE/ F-2-derived peptide in this study could be explained by its possible unique role in MHC peptide binding and/or by its abundance because pmpF also has the highest mRNA expression level among tested C. trachomatis strains (40). PmpG has also been identified as recognized by CD4 T cells during C. pneumoniae infection in mice (41).…”

Polymorphisms in Inc Proteins and Differential Expression ofincGenes among Chlamydia trachomatis Strains Correlate with Invasiveness and Tropism of Lymphogranuloma Venereum Isolates

“…The expression of inc genes during the developmental cycle of C. trachomatis B/Har36, C/TW3, E/Bour, F/CS465-95, L2/434, L2b/CS19-08, and L3/404 was estimated by determining inc mRNA levels at different times postinfection by real-time quantitative PCR (RT-qPCR). These experiments were essentially done as previously described (7,42). Briefly, for each strain, six tissue culture flasks with a surface area of 25 cm 2 containing monolayers of HeLa 229 cells were inoculated at a multiplicity of infection of 1; cells were harvested at 2,6,12,20,30, and 42 h postinfection by scraping in ice-cold phosphate-buffered saline.…”

A characteristic of polymorphic membrane protein F of Chlamydia trachomatis isolated from male urogenital tracts in Japan

“…As a homosexual male reference group, seven of the male strains obtained from rectums in the current study (Strain numbers: 70, 150, 2923, 6276, 9301, 9768, 11023, 11074, and 11222) that has been reported previously [18], were also used for the study. Furthermore, as female strain groups, eleven of the female strains used in the present study were previously isolated from Sapporo, Japan (Strain designations: nv266, nv283, nv287, nv307, nv381, nv399, nv441, nv417, nv437, nv443, and nv448), as previously reported [19] S-91, 537C-05, S-141, and CS-500-96) had also been previously reported [11,16] (Category: Ref-females). The origins and accession numbers of all of the strains are summarized in Table 1.…”

“…In contrast to the β-barrel domain, the PmpF passenger domains have been shown to undergone amino acid changes throughout evolution because of surface localization [13][14][15]. Thus, polymorphism of the PmpF passage domain, which is exposed to strong host-selective pressures, has been thought to be a candidate high-definition phylogenetic marker [8][9][10][11][12][13]. The Japan-female strains isolated from cervical ducts with microbial flora were very diverse in agreement with the Ref-females as well as previous findings [12,13].…”

“…To date, most studies of C. trachomatis bacterial traits have focused on strains isolated from women, whereas the study of bacteria from the male urogenital tract has been hindered by difficulties in the isolation of organisms. Meanwhile, accumulating evidences have revealed a high-definition phylogenetic marker, polymorphic membrane protein (Pmp), which diversifies into nine Pmp families (A-I) in C. trachomatis [8][9][10][11][12][13].…”