PubMed HealthSearch

PubMed · 2188922

Trachoma.

Abstract

Trachoma causes one-quarter of the world's blindness and, although it has disappeared from many developed areas, it remains a major problem, especially in underprivileged rural areas in developing countries. Recent advances in the understanding of the molecular biology of chlamydia offer encouragement for the eventual development for an effective trachoma vaccine. Advances in the understanding of the epidemiology of trachoma, particularly of the importance of reinfection and the intrafamily transmission of infection, have led to the identification of the key importance of simple hygiene measures such as facial cleanliness in preventing the transmission of trachoma. Community-based health education intervention programs are being developed to assess the efficacy of a public health approach to the control of trachomatous blindness.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

H R Taylor. 1990. Trachoma.. https://doi.org/10.1007/bf00158319

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Genome-wide identification of modulators of Chlamydia trachomatis parasitophorous vacuole stability highlights an important role for sphingolipid supply.

A mechanistic understanding of how intracellular pathogens evade the intrinsic defenses of their host cells could open up intriguing therapeutic opportunities. Here, we applied a genome-wide genetic screening approach to investigate the nature of the defensive host cell death response suppressed by the membrane trafficking modulator CpoS, an effector protein secreted by the obligate intracellular bacterial pathogen Chlamydia trachomatis. Initially, this work revealed a CpoS-deficient mutant to exhibit a markedly increased dependence on host cellular synthesis of ceramides, the precursors of complex sphingolipids. Using novel microscopic reporters, we then established CpoS' role in defense evasion to occur by preserving the integrity of Chlamydia's parasitophorous vacuole (the inclusion) via ensuring an adequate sphingolipid supply. More specifically, we observed CpoS deficiency to destabilize inclusions, initially characterized by a release of individual bacteria into the host cell cytosol, then followed by inclusion rupture concomitant with host cell death. Exogenous addition of sphingosine stabilized CpoS-deficient inclusions, whereas disruption of host cellular ceramide synthesis destabilized wild-type inclusions. In combination, CpoS deficiency and impaired ceramide synthesis - presumably disrupting both Chlamydia's vesicular and non-vesicular sphingolipid supply routes - destabilized inclusions even earlier, resulting in infection clearance and host cell survival rather than host cell death. Overall, this study highlights how the vacuolar pathogen C. trachomatis maintains vacuole integrity by ensuring a steady sphingolipid supply, potentially offering inspiration and directions for future therapeutic strategies targeting parasitophorous vacuoles.

Chlamydia trachomatis

A platform supporting generation and isolation of random transposon mutants in Chlamydia trachomatis.

Chlamydia species represent a paradigm for understanding successful obligate intracellular parasitism. Despite limited genetic malleability, development of genetic tools has facilitated the elucidation of molecular mechanisms governing infectivity. Random mutagenesis approaches provide one of the most powerful strategies available to accomplish untargeted elucidation of gene function. Unfortunately, initial progress in transposon-mediated mutagenesis of Chlamydia has been challenging. To increase efficiency, we developed a plasmid-based system that couples conditional plasmid maintenance with a previously described strategy leveraging inducible expression of the Himar1-derived C9 transposase. Our pOri-Tn(Q) construct was maintained in Chlamydia trachomatis cultivated with antibiotics but was rapidly cured in the absence of antibiotic selection. pOri-Tn(Q) supported transposition events when transposase expression was induced during infection. Induction was accompanied by loss of the plasmid backbone when penicillin G was used to select for only the transposable element. C9 induction during iterative passaging was used to increase the overall insertion frequency and accumulate an expanded pool of transposon mutants. The approach supported isolation of individual mutant strains from the mixed pool, and whole-genome sequencing confirmed that the recovered strains harbored single insertions.IMPORTANCEChlamydia trachomatis is a prevalent human pathogen exerting a tremendous negative impact on human health. A complete understanding of how these bacteria create and maintain an intracellular niche and avoid/subvert host defense mechanisms to cause disease is lacking. The utility of transposon-mediated, random mutagenesis in supporting forward genetic studies is well established in a multitude of genetically tractable systems. This study reports the development of a plasmid-based system capable of generating mutant pools and supporting subsequent isolation of individual transposon mutants. This step is an important advance in providing a mechanism capable of supporting downstream studies interrogating chlamydial biology.

Chlamydia trachomatis

Whole-genome automated assembly pipeline for Chlamydia trachomatis strains from reference, in vitro and clinical samples using the integrated CtGAP pipeline.

Whole genome sequencing (WGS) is pivotal for the molecular characterization of Chlamydia trachomatis (Ct)-the leading bacterial cause of sexually transmitted infections and infectious blindness worldwide. Ct WGS can inform epidemiologic, public health and outbreak investigations of these human-restricted pathogens. However, challenges persist in generating high-quality genomes for downstream analyses given its obligate intracellular nature and difficulty with in vitro propagation. No single tool exists for the entirety of Ct genome assembly, necessitating the adaptation of multiple programs with varying success. Compounding this issue is the absence of reliable Ct reference strain genomes. We, therefore, developed CtGAP-Chlamydia trachomatisGenome Assembly Pipeline-as an integrated 'one-stop-shop' pipeline for assembly and characterization of Ct genome sequencing data from various sources including isolates, in vitro samples, clinical swabs and urine. CtGAP, written in Snakemake, enables read quality statistics output, adapter and quality trimming, host read removal, de novo and reference-guided assembly, contig scaffolding, selective ompA, multi-locus-sequence and plasmid typing, phylogenetic tree construction, and recombinant genome identification. Twenty Ct reference genomes were also generated. Successfully validated on a diverse collection of 363 samples containing Ct, CtGAP represents a novel pipeline requiring minimal bioinformatics expertise with easy adaptation for use with other bacterial species.

Chlamydia trachomatis