14 research outputs found

    Frameshift Mutations in a Single Novel Virulence Factor Alter the In Vivo Pathogenicity of Chlamydia trachomatis for the Female Murine Genital Tract▿ ¶ ‖

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    Chlamydia trachomatis is a human pathogen of global importance. An obstacle to studying the pathophysiology of human chlamydial disease is the lack of a suitable murine model of C. trachomatis infection. Mice are less susceptible to infection with human isolates due in part to innate mouse-specific host defense mechanisms to which human strains are sensitive. Another possible factor that influences the susceptibility of mice to infection is that human isolates are commonly cultivated in vitro prior to infection of mice; therefore, virulence genes could be lost as a consequence of negative selective pressure. We tested this hypothesis by infecting innate immunity-deficient C3H/HeJ female mice intravaginally with a human serovar D urogenital isolate that had undergone multiple in vitro passages. We observed early and late infection clearance phenotypes. Strains of each phenotype were isolated and then used to reinfect naïve mice. Following infection, the late-clearance strain was significantly more virulent. It caused unvarying infections of much longer durations with greater infectious burdens that naturally ascended to the upper genital tract, causing salpingitis. Despite contrasting in vivo virulence characteristics, the strains exhibited no differences in the results of in vitro infectivity assays or sensitivities to gamma interferon. Genome sequencing of the strains revealed mutations that localized to a single gene (CT135), implicating it as a critical virulence factor. Mutations in CT135 were not unique to serovar D but were also found in multiple oculogenital reference strains. Our findings provide new information about the pathogenomics of chlamydial infection and insights for improving murine models of infection using human strains

    The type 2 diabetes and insulin-resistance locus near IRS1 is a determinant of HDL cholesterol and triglycerides levels among diabetic subjects

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    Objective: SNP rs2943641 near the insulin receptor substrate 1 (IRS1) gene has been found to be associated with type 2 diabetes (T2D) and insulin-resistance in genome-wide association studies. We investigated whether this SNP is associated with cardiovascular risk factors and coronary artery disease (CAD) among diabetic individuals. Methods: SNP rs2943641 was typed in 2133 White T2D subjects and tested for association with BMI, serum HDL cholesterol and triglycerides, hypertension history, and CAD risk. Results: HDL cholesterol decreased by 1 mg/dl (p = 0.004) and serum triglycerides increased by 6 mg/dl (p = 0.016) for each copy of the insulin-resistance allele. Despite these effects, no association was found with increased CAD risk (OR = 1.00, 95% CI 0.88-1.13). Conclusions: The insulin-resistance and T2D locus near the IRS1 gene is a determinant of lower HDL cholesterol among T2D subjects. However, this effect is small and does not translate into a detectable increase in CAD risk in this population. (C) 2011 Elsevier Ireland Ltd. All rights reserved
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