title: The Chlamydia trachomatis plasmid is a transcriptional regulator of chromosomal genes and a virulence factor.
abstract: Chlamydia trachomatis possesses a cryptic 7.5-kb plasmid of unknown function. Here, we describe a comprehensive molecular and biological characterization of the naturally occurring plasmidless human C. trachomatis strain L2(25667R). We found that despite minimal chromosomal polymorphisms, the LGV strain L2(25667R) was indistinguishable from plasmid-positive strain L2(434) with regard to its in vitro infectivity characteristics such as growth kinetics, plaquing efficiency, and plaque size. The only in vitro phenotypic differences between L2(434) and L2(25667R) were the accumulation of glycogen granules in the inclusion matrix and the lack of the typical intrainclusion Brownian-like movement characteristic of C. trachomatis strains. Conversely, we observed a marked difference between the two strains in their abilities to colonize and infect the female mouse genital tract. The 50% infective dose of plasmidless strain L2(25667R) was 400-fold greater (4 x 10(6) inclusion-forming units [IFU]) than that of plasmid-bearing strain L2(434) (1 x 10(4) IFU). Transcriptome analysis of the two strains demonstrated a decrease in the transcript levels of a subset of chromosomal genes for strain L2(25667R). Among those genes was glgA, encoding glycogen synthase, a finding consistent with the failure of L2(25667R) to accumulate glycogen granules. These findings support a primary role for the plasmid in in vivo infectivity and suggest that virulence is controlled, at least in part, by the plasmid's ability to regulate the expression of chromosomal genes. Our findings have important implications in understanding a role for the plasmid in the pathogenesis of human infection and disease.
authors.affiliation: Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South 4th Street, Hamilton, MT 59840, USA.
authors.forename: John H
authors.initials: JH
authors.lastname: Carlson
authors.forename: William M
authors.initials: WM
authors.lastname: Whitmire
authors.forename: Deborah D
authors.initials: DD
authors.lastname: Crane
authors.forename: Luke
authors.initials: L
authors.lastname: Wicke
authors.forename: Kimmo
authors.initials: K
authors.lastname: Virtaneva
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Sturdevant
authors.forename: John J
authors.initials: JJ
authors.lastname: Kupko
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Porcella
authors.forename: Neysha
authors.initials: N
authors.lastname: Martinez-Orengo
authors.forename: Robert A
authors.initials: RA
authors.lastname: Heinzen
authors.forename: Laszlo
authors.initials: L
authors.lastname: Kari
authors.forename: Harlan D
authors.initials: HD
authors.lastname: Caldwell
mesh_terms: D000818:Animals; D001431:Bacteriological Techniques; D002690:Chlamydia Infections / Q000382:microbiology; D002692:Chlamydia trachomatis / Q000145:classification / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D002876:Chromosomes, Bacterial / Q000235:genetics*; D005260:Female; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D051379:Mice; D008809:Mice, Inbred C3H; D010957:Plasmids / Q000235:genetics / Q000502:physiology*; D011110:Polymorphism, Genetic; D040081:Protein Array Analysis; D014158:Transcription, Genetic / Q000502:physiology*; D016585:Vaginosis, Bacterial / Q000382:microbiology; D037521:Virulence Factors / Q000235:genetics / Q000502:physiology*
chemical_list: D037521:Virulence Factors