Browsing by Author "Santiviago, Carlos A."

Now showing 1 - 4 of 4
  • No Thumbnail Available
    Item
    Deletion of a prophage-like element causes attenuation of Salmonella enterica serovar Enteritidis and promotes protective immunity
    (2010) Araya, Daniela V.; Quiroz, Tania S.; Tobar, Hugo E.; Lizana, Rodrigo J.; Quezada, Carolina P.; Santiviago, Carlos A.; Riedel, Claudia A.; Kalergis, Alexis M.; Bueno, Susan M.
    Salmonella enterica serovar Enteritidis (S Enteritidis) is a wide host range serovar belonging to the S. enterica genus. Worldwide, it is one of the most frequent causes of food borne disease Similar to S. Typhimurium, some virulence genes of S. Enteritidis are located in pathogenicity islands and prophages. In this study we have generated a mutant strain of S. Enteritidis lacking a prophage-like element, denominated phi SE12. The resulting mutant strain was attenuated and promoted protective immunity in infected mice Although S Enteritidis strains lacking the complete prophage phi SE12 remained capable of surviving inside phagocytic cells, they showed a significantly reduced capacity to colonize internal organs and failed to cause lethal disease in mice. Consistent with these data, infection with S Enteritidis strains lacking prophage phi SE12 promoted the production of anti-Salmonella IgG antibodies and led to protection against a challenge with virulent strains of S Enteritidis. These results suggest that strains lacking this prophage can induce a protective immunity in mice and be considered as potential attenuated vaccines against S Enteritidis. (C) 2010 Elsevier Ltd All rights reserved
  • Thumbnail Image
    Item
    Excision of an Unstable Pathogenicity Island in Salmonella enterica Serovar Enteritidis Is Induced during Infection of Phagocytic Cells
    (PUBLIC LIBRARY SCIENCE, 2011) Quiroz, Tania S.; Nieto, Pamela A.; Tobar, Hugo E.; Salazar Echegarai, Francisco J.; Lizana, Rodrigo J.; Quezada, Carolina P.; Santiviago, Carlos A.; Araya, Daniela V.; Riedel, Claudia A.; Kalergis, Alexis M.; Bueno, Susan M.
    The availability of the complete genome sequence of several Salmonella enterica serovars has revealed the presence of unstable genetic elements in these bacteria, such as pathogenicity islands and prophages. This is the case of Salmonella enterica serovar Enteritidis (S. Enteritidis), a bacterium that causes gastroenteritis in humans and systemic infection in mice. The whole genome sequence analysis for S. Enteritidis unveiled the presence of several genetic regions that are absent in other Salmonella serovars. These regions have been denominated "regions of difference'' (ROD). In this study we show that ROD21, one of such regions, behaves as an unstable pathogenicity island. We observed that ROD21 undergoes spontaneous excision by two independent recombination events, either under laboratory growth conditions or during infection of murine cells. Importantly, we also found that one type of excision occurred at higher rates when S. Enteritidis was residing inside murine phagocytic cells. These data suggest that ROD21 is an unstable pathogenicity island, whose frequency of excision depends on the environmental conditions found inside phagocytic cells.
  • Thumbnail Image
    Item
    Identification of Type VI Secretion Systems Effector Proteins That Contribute to Interbacterial Competition in Salmonella Dublin
    (FRONTIERS MEDIA SA, 2022) Amaya, Fernando A.; Blondel, Carlos J.; Barros Infante, Maria F.; Rivera, Dacil; Moreno Switt, Andrea I.; Santiviago, Carlos A.; Pezoa, David
    The Type VI Secretion System (T6SS) is a multiprotein device that has emerged as an important fitness and virulence factor for many Gram-negative bacteria through the injection of effector proteins into prokaryotic or eukaryotic cells via a contractile mechanism. While some effector proteins specifically target bacterial or eukaryotic cells, others can target both types of cells (trans-kingdom effectors). In Salmonella, five T6SS gene clusters have been identified within pathogenicity islands SPI-6, SPI-19, SPI-20, SPI-21, and SPI-22, which are differentially distributed among serotypes. Salmonella enterica serotype Dublin (S. Dublin) is a cattle-adapted pathogen that harbors both T6SS(SPI-6) and T6SS(SPI-19). Interestingly, while both systems have been linked to virulence and host colonization in S. Dublin, an antibacterial activity has not been detected for T6SS(SPI-6) in this serotype. In addition, there is limited information regarding the repertoire of effector proteins encoded within T6SS(SPI-6) and T6SS(SPI-19) gene clusters in S. Dublin. In the present study, we demonstrate that T6SS(SPI-6) and T6SS(SPI-19) of S. Dublin CT_02021853 contribute to interbacterial competition. Bioinformatic and comparative genomic analyses allowed us to identify genes encoding three candidate antibacterial effectors located within SPI-6 and two candidate effectors located within SPI-19. Each antibacterial effector gene is located upstream of a gene encoding a hypothetic immunity protein, thus conforming an effector/immunity (E/I) module. Of note, the genes encoding these effectors and immunity proteins are widely distributed in Salmonella genomes, suggesting a relevant role in interbacterial competition and virulence. Finally, we demonstrate that E/I modules SED_RS01930/SED_RS01935 (encoded in SPI-6), SED_RS06235/SED_RS06230, and SED_RS06335/SED_RS06340 (both encoded in SPI-19) contribute to interbacterial competition in S. Dublin CT_02021853.
  • No Thumbnail Available
    Item
    SEN1990 is a predicted winged helix-turn-helix protein involved in the pathogenicity of Salmonella enterica serovar Enteritidis and the expression of the gene oafB in the SPI-17
    (2023) Hoppe-Elsholz, Guillermo; Pina-Iturbe, Alejandro; Vallejos, Omar P.; Suazo, Isidora D.; Sepulveda-Alfaro, Javiera; Pereira-Sanchez, Patricia; Martinez-Balboa, Yohana; Catalan, Eduardo A.; Reyes, Pablo; Scaff, Valentina; Bassi, Franco; Campos-Gajardo, Sofia; Aviles, Andrea; Santiviago, Carlos A.; Kalergis, Alexis M.; Bueno, Susan M.
    Excisable genomic islands (EGIs) are horizontally acquired genetic elements that harbor an array of genes with diverse functions. ROD21 is an EGI found integrated in the chromosome of Salmonella enterica serovar Enteritidis (Salmonella ser. Enteritidis). While this island is known to be involved in the capacity of Salmonella ser. Enteritidis to cross the epithelial barrier and colonize sterile organs, the role of most ROD21 genes remains unknown, and thus, the identification of their function is fundamental to understanding the impact of this EGI on bacterium pathogenicity. Therefore, in this study, we used a bioinformatical approach to evaluate the function of ROD21-encoded genes and delve into the characterization of SEN1990, a gene encoding a putative DNA-binding protein. We characterized the predicted structure of SEN1990, finding that this protein contains a three-stranded winged helix-turn-helix (wHTH) DNA-binding domain. Additionally, we identified homologs of SEN1990 among other members of the EARL EGIs. Furthermore, we deleted SEN1990 in Salmonella ser. Enteritidis, finding no differences in the replication or maintenance of the excised ROD21, contrary to what the previous Refseq annotation of the protein suggests. High-throughput RNA sequencing was carried out to evaluate the effect of the absence of SEN1990 on the bacterium's global transcription. We found a downregulated expression of oafB, an SPI-17-encoded acetyltransferase involved in O-antigen modification, which was restored when the deletion mutant was complemented ectopically. Additionally, we found that strains lacking SEN1990 had a reduced capacity to colonize sterile organs in mice. Our findings suggest that SEN1990 encodes a wHTH domain-containing protein that modulates the transcription of oafB from the SPI-17, implying a crosstalk between these pathogenicity islands and a possible new role of ROD21 in the pathogenesis of Salmonella ser. Enteritidis.