Browsing by Author "Rivera, Dacil"

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    Comparative Analysis of Felixounavirus Genomes Including Two New Members of the Genus That Infect Salmonella Infantis
    (MDPI, 2021) Barron Montenegro, Rocio; Garcia, Rodrigo; Duenas, Fernando; Rivera, Dacil; Opazo Capurro, Andres; Erickson, Stephen; Moreno Switt, Andrea, I
    Salmonella spp. is one of the most common foodborne pathogens worldwide; therefore, its control is highly relevant for the food industry. Phages of the Felixounavirus genus have the characteristic that one phage can infect a large number of different Salmonella serovars and, thus, are proposed as an alternative to antimicrobials in food production. Here, we describe two new members of the Felixounavirus genus named vB_Si_35FD and vB_Si_DR94, which can infect Salmonella Infantis. These new members were isolated and sequenced, and a subsequent comparative genomic analysis was conducted including 23 publicly available genomes of Felixounaviruses that infect Salmonella. The genomes of vB_Si_35FD and vB_Si_DR94 are 85,818 and 85,730 bp large and contain 129 and 125 coding sequences, respectively. The genomes did not show genes associated with virulence or antimicrobial resistance, which could be useful for candidates to use as biocontrol agents. Comparative genomics revealed that closely related Felixounavirus are found in distinct geographical locations and that this genus has a conserved genomic structure despite its worldwide distribution. Our study revealed a highly conserved structure of the phage genomes, and the two newly described phages could represent promising biocontrol candidates against Salmonella spp. from a genomic viewpoint.
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    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.