title: In vitro passage selects for Chlamydia muridarum with enhanced infectivity in cultured cells but attenuated pathogenicity in mouse upper genital tract.
abstract: Although modern Chlamydia muridarum has been passaged for decades, there are no reports on the consequences of serial passage with strong selection pressure on its fitness. In order to explore the potential for Pasteurian selection to induce genomic and phenotypic perturbations to C. muridarum, a starter population was passaged in cultured cells for 28 generations without standard infection assistance. The resultant population, designated CMG28, displays markedly reduced in vitro dependence on centrifugation for infection and low incidence and severity of upper genital tract pathology following intravaginal inoculation into mice compared to the parental C. muridarum population, CMG0. Deep sequencing of CMG0 and CMG28 revealed novel protein variants in the hypothetical genes TC0237 (Q117E) and TC0668 (G322R). In vitro attachment assays of isogenic plaque clone pairs with mutations in either TC0237 and TC0668 or only TC0237 reveal that TC0237(Q117E) is solely responsible for enhanced adherence to host cells. Paradoxically, double mutants, but not TC0237(Q117E) single mutants, display severely attenuated in vivo pathogenicity. These findings implicate TC0237 and TC0668 as novel genetic factors involved in chlamydial attachment and pathogenicity, respectively, and show that serial passage under selection pressure remains an effective tool for studying Chlamydia pathogenicity.
authors.affiliation: Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA Departments of Microbiology and Immunology, Institute of Pathobiology, University of South China, Hengyang, Hunan, People's Republic of China.
authors.forename: Chaoqun
authors.initials: C
authors.lastname: Chen
authors.affiliation: Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA Departments of Microbiology and Immunology, Institute of Pathobiology, University of South China, Hengyang, Hunan, People's Republic of China.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.
authors.forename: Turner
authors.initials: T
authors.lastname: Conrad
authors.affiliation: Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.
authors.forename: Zhangsheng
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.
authors.forename: Jin
authors.initials: J
authors.lastname: Dai
authors.affiliation: Departments of Microbiology and Immunology, Institute of Pathobiology, University of South China, Hengyang, Hunan, People's Republic of China.
authors.forename: Zhongyu
authors.initials: Z
authors.lastname: Li
authors.affiliation: Departments of Microbiology and Immunology, Institute of Pathobiology, University of South China, Hengyang, Hunan, People's Republic of China yimouwu@sina.com Zhongg@UTHSCSA.edu.
authors.forename: Yimou
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA yimouwu@sina.com Zhongg@UTHSCSA.edu.
authors.forename: Guangming
authors.initials: G
authors.lastname: Zhong
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D002690:Chlamydia Infections / Q000382:microbiology / Q000473:pathology*; D023502:Chlamydia muridarum / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005260:Female; D006367:HeLa Cells; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008809:Mice, Inbred C3H; D060737:Reproductive Tract Infections / Q000382:microbiology / Q000473:pathology*; D012641:Selection, Genetic; D012692:Serial Passage; D014774:Virulence
chemical_list: D004269:DNA, Bacterial