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Browsing by Subject "Campylobacter coli"

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  • Evaluating the effect of different growth conditions on glycoconjugate expression in Campylobacter coli : a methodological perspective 
    Galeev, Alibek (2016)
    Campylobacter species, particularly C. jejuni and C. coli, are the most common cause of human gastroenteritis worldwide. Lipooligosaccharides (LOS) are heat-stable amphiphilic glycolipids essential for viability and outer membrane stability of Gram-negative bacteria. LOS trigger the activation of both innate and adaptive immune systems. This project aimed to investigate variability of C. coli LOS expression under different growth conditions and its impact on immunogenicity. Moreover, it aims to highlight possible method-based biases in investigating LOS-host interaction. In this study the LOS of eight C. coli strains were extracted by three different methods. Despite differences in growth conditions, the electrophoretic mobility of analyzed LOS was consistent within strains. SDS-PAGE analysis and TLR4 activation assay revealed a significant overestimation of the LOS concentration in the samples by the commonly used LOS quantitation method – purpald assay. Furthermore, it was shown that standardization of lyophilized LOS samples by weight lead to an incorrect estimation of LOS concentration. In conclusion, growth conditions did not cause a visible change in the electrophoretic mobility, suggesting no significant changes in LOS expression. Crude LPS extraction was suitable for LOS profiling and immune response evaluation in HEK-TLR4 cells. LOS quantitation by weight and/or by the purpald assay may result in incorrect estimation of LOS concentration and it might significantly affect downstream immunological analyses. The results of this thesis suggest that the validity of data produced using LOS quantified with either purpald assay or weight of lyophilized material should be critically reassessed.
  • Molecular typing of Campylobacter coli strains isolated from different sources 
    Culebro, Alejandra (2013)
    Campylobacteriosis, the most common bacterial food-borne disease worldwide, is mainly caused by Campylobacter jejuni and C. coli. Most studies have focused on the genetic diversity of C. jejuni, but little is known about C. coli. The aim of this work was to characterize C. coli from different sources, by evaluating the distribution and/or diversity of certain genetic markers. A total of 145 C. coli isolates from different sources (2 goose, 18 poultry, 35 human and 90 swine) were screened for fucP, ggt, cytC, sialyltransferases genes and CRISPRs. Additionally, the diversity of the LOS loci and of the CRISPRs, were assessed. A frequency of 90.34% was observed for fucP and CRISPRs among C. coli. Conversely, the frequency of GGT phenotype, and cytC, and cst-I genotype was 1.38%, while cst-V genotype was 0.69%. Only one isolate was positive for all markers except fucP; no source association was observed. LOS and CRISPRs exhibited a wide diversity. In conclusion, ggt, fucP, and cytC seem to be lineage related in C. coli, and not host associated. CRISPRs were too discriminatory to be of use in epidemiological investigations. Results suggest a high diversity of the LOS, and there may exist more classes than those previously described.

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