Evaluation of changes in virulence gene expression in Salmonella enterica serovar Enteritidis resulting from deletion of genes associated to the excision of the pathogenicity island ROD21.
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2023
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Abstract
Pathogenicity islands (PAIs) are mobile genetic elements acquired by horizontal gene transfer in bacteria. Some PAIs have been described as excisable elements, in which the excision process involves several proteins that are encoded within and outside the PAIs, among them, an integrase and a recombination directionality factor (RDF). This process is involved in the regulation of bacterial gene expression and virulence. Salmonella enterica serovar Enteritidis (SEn) is a pathogenic Gram-negative bacteria, which possesses several PAIs. One of them, known as ROD21, is an excisable PAI that has been linked to virulence in mice and poultry. In the case of ROD21, the genes SEN1970 and SEN1998 encode an integrase and an RDF, respectively. We developed a new mutant SEn strain lacking both SEN1970 and SEN1998 which in contrast to previous results showed us that the lack of these genes in SEn has no significant effect on the frequency of ROD21 excision, but it indeed has an impact on the transcriptional pattern of SEn, particularly affecting the transcription of genes located in SPI-2. In vivo experiments in mice also showed a differential capacity of our mutant SEn to reach levels of colonization at later stages of infection, as compared to the wild-type SEn strain. These results have led us to conclude that SEN1970 and SEN1998 are not essential for ROD21 excision but do have a possible role in regulating the transcription of virulence genes located in other pathogenicity islands, affecting the ability of SEn to cause systemic infection in mice.
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Tesis (Doctor in Sciences with mention in Molecular Genetics and Microbiology)--Pontificia Universidad Católica de Chile, 2023.
TESIS EMBARGADA HASTA EL 11 DE DICIEMBRE DE 2024
TESIS EMBARGADA HASTA EL 11 DE DICIEMBRE DE 2024