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Title:GENETSKA VARIABILNOST TOKSINSKEGA LOKUSA CdtLoc PRI RAZLIČNIH TOKSINOTIPIH BAKTERIJE Clostridium difficile
Authors:ID Rikanović, Tanja (Author)
ID Rupnik, Maja (Mentor) More about this mentor... New window
ID Janežič, Sandra (Comentor)
Files:.pdf MAG_Rikanovic_Tanja_2016.pdf (1,99 MB)
MD5: 4C35E7667638FADF4419E889B61ACA72
 
Language:Slovenian
Work type:Master's thesis/paper
Typology:2.09 - Master's Thesis
Organization:FZV - Faculty of Health Sciences
Abstract:Izhodišča: Clostridium difficile, črevesna patogena bakterija, je ena izmed najpomembnejših povzročiteljev bolnišničnih okužb na svetu. Bolezen povzročajo toksigeni sevi, ki izdelujejo toksin A in/ali toksin B. Oba sta zapisana na toksinskem lokusu PaLoc. PaLoc se nahaja v bakterijskem kromosomu in je zelo dobro raziskan genetski element. Glede na razlike v PaLoc-u lahko seve razdelimo v različne toksinotipe. Nekateri sevi C. difficile izdelujejo še tretji toksin, binarni toksin CDT, katerega vloga pri razvoju bolezni pa še ni povsem pojasnjena, vendar zadnje raziskave potrjujejo, da postaja pomemben člen v patogenezi okužbe s C. difficile. Zapis za binarni toksin se prav tako nahaja v kromosomu, na lokusu imenovanem lokus Cdt (CdtLoc), ki je mnogo slabše raziskan kot PaLoc. Metodologija: V raziskavi smo z bioinformatskimi orodji (Artemis, BioEdit Sequence Alignment Editor in MEGA) analizirali lokus Cdt in gene, ki se nahajajo navzgor in navzdol od CdtLoc-a, ter tako preverili ali se nahaja vedno na istem mestu v genomu. Genetsko variabilnost genov, ki sestavljata CdtLoc (cdtA in cdtB) smo določili na nukleotidnem in aminokislinskem zaporedju. Sorodnosti med sevi smo predstavili s konstrukcijo filogenetskih dreves za kar smo uporabili algoritem združevanja sosedov. Rezultati: Ugotovili smo, da lokus Cdt pri vseh predstavnikih toksinotipov vključenih v analizo leži na istem mestu v kromosomu. Analiza nukleotidnega in aminokislinskega zaporedja nam je pokazala, da se v genih, ki sestavljata CdtLoc, pojavljajo le točkovne mutacije, ki so večinoma enakomerno razporejene po celotni dolžini gena, rahlo je povišano le njihovo število na 5'-koncu cdtB gena. Filogenetska analiza na podlagi vseh treh genov, ki sestavljajo CdtLoc in združenih MLST lokusov, pa je pokazala enake sorodstvene odnose med sevi. Sklep: Naši rezultati kažejo, da se CdtLoc nahaja vedno na istem mestu v genomu in da k variabilnosti obeh toksinskih genov največ prispevajo točkovne mutacije. Glede na ujemanje filogenetskih dreves na podlagi genov CdtLoc-a in MLST lahko sklepamo, da se lokus Cdt verjetno prenaša primarno vertikalno.
Keywords:Clostridium difficile, binarni toksin, toksinski lokus CdtLoc, genetska variabilnost, toksinotip.
Place of publishing:Maribor
Publisher:[T. Rikanović]
Year of publishing:2016
PID:20.500.12556/DKUM-59777 New window
UDC:579.25(043.2)
COBISS.SI-ID:2219684 New window
NUK URN:URN:SI:UM:DK:D91CSVWE
Publication date in DKUM:01.09.2016
Views:2902
Downloads:142
Metadata:XML DC-XML DC-RDF
Categories:FZV
:
RIKANOVIĆ, Tanja, 2016, GENETSKA VARIABILNOST TOKSINSKEGA LOKUSA CdtLoc PRI RAZLIČNIH TOKSINOTIPIH BAKTERIJE Clostridium difficile [online]. Master’s thesis. Maribor : T. Rikanović. [Accessed 29 March 2025]. Retrieved from: https://dk.um.si/IzpisGradiva.php?lang=eng&id=59777
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Secondary language

Language:English
Title:GENETIC VARIABILITY OF BINARY TOXIN CDT CODING LOCUS IN DIFFERENT Clostridium difficile TOXINOTYPES
Abstract:Introduction: Clostridium difficile is a nosocomial pathogen and it is one of the most important causes of health care-associated infections. Disease is caused only by toxigenic strains that produce toxin A and/or toxin B, which are the main virulence factors encoded in the pathogenicity locus PaLoc. PaLoc, a well defined genetic element, is located in the chromosome. Based on the changes in the PaLoc strains can be distributed into different toxinotypes. Some C. difficile strains can produce also a third toxin, binary toxin CDT. Even though its role in disease is still unclear, latest studies suggests that CDT could play an important part in the pathogenesis of C. difficile infection. Binary toxin is encoded in the binary toxin locus, named CdtLoc. Like PaLoc, CdtLoc is also found in the chromosome, but its genetic variability is less studied compared to the PaLoc. Methodology: The aim of this study was to analyze the binary locus Cdt and to check whether CdtLoc is integrated always at the same location in the genome by analysis of genes located upstream and downstream of the CdtLoc, using different bioinformatics tools (Artemis, BioEdit Sequence Alignment Editor and MEGA). Genetic variability of both toxin genes (cdtA and cdtB) was defined on the nucleotide and amino acid sequences. Furthermore, phylogenetic relationships between different strains based on binary toxin genes were explored with the construction of phylogenetic trees using neighbor-joining algorithm. Results: In all 20 analyzed strains was CdtLoc inserted in the same chromosomal site. Analysis of nucleotide and amino acid sequences demonstrated that genetic variability of CdtLoc is due to accumulation of point mutations. Point mutations were more or less equally distributed through the toxin genes, their number is slightly increased only on the 5'-end of the cdtB gene. Also, phylogenies based on all three genes, encoded in the CdtLoc (cdtA, cdtB and cdtR) were congruent with phylogeny demonstrated with concatenated MLST loci. Conclusion: Our results indicate the same chromosomal integration site of CdtLoc and that point mutation are responsible for the genetic variability of both toxin genes. Congruent phylogenetic relationships based on CdtLoc genes and MLST indicate that the transfer of the binary locus Cdt is primarily vertical.
Keywords:Clostridium difficile, binary toxin CDT, CDT coding locus CdtLoc, genetic variability, toxinotypes.


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