Chlamydial Plasmid-Dependent Pathogenicity

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Abstract

Most . Chlamydia species carry a 7.5. kb plasmid encoding eight open reading frames conventionally called plasmid glycoproteins 1-8 or pGP1-8. Although the plasmid is not critical for chlamydial growth . in vitro, its role in chlamydial pathogenesis is clearly demonstrated in the genital tracts of mice infected with . Chlamydia muridarum, a model for investigating the human pathogen . Chlamydia trachomatis. Plasmid-free . C. trachomatis is also attenuated in both the mouse genital tract and nonhuman primate ocular tissue. Deficiency in pGP3 alone, which is regulated by pGP4, largely reproduced the . in vivo but not . in vitro phenotypes of the plasmid-free organisms, suggesting that pGP3 is a key . in vivo virulence factor. The positive and negative regulations of some chromosomal genes by pGP4 and pGP5, respectively, may allow the plasmid to promote chlamydial adaptation to varied animal tissue environments. The focus of this review is to summarize the progress on the pathogenic functions of the plasmid-encoded open reading frames, which may motivate further investigation of the molecular mechanisms of chlamydial pathogenicity and development of medical utility of the chlamydial plasmid system. The plasmid is less important for chlamydial growth . in vitro than during infection . in vivo, suggesting that . Chlamydia may have acquired the plasmid for promoting its survival in animals, implicating a plasmid-dependent pathogenicity.pGP3-deficiency reproduced the . in vivo but not the . in vitro phenotypes of plasmid deficiency, indicating that pGP3 is a key virulence factor for the plasmid-dependent pathogenicity. pGP3 may exert its pathogenicity by promoting both chlamydial ascending infection and induction of tubal inflammation.pGP4 is a master transcriptional regulator for both plasmid genes, including . pgp3 and chromosomal genes such as . glgA and type III secretion effector genes. pGP4 promotes chlamydial exit from infected cells in cell culture.pGP5 appears to be a negative regulator of the chlamydial chromosomal genes that are upregulated by pGP4.

Original languageEnglish (US)
JournalTrends in Microbiology
DOIs
StateAccepted/In press - 2016

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ASJC Scopus subject areas

  • Microbiology
  • Microbiology (medical)
  • Infectious Diseases
  • Virology

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