The Experts below are selected from a list of 50961 Experts worldwide ranked by ideXlab platform
Dipshikha Chakravortty - One of the best experts on this subject based on the ideXlab platform.
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host specificity of Salmonella enterica serovar gallinarum insights from comparative genomics
Infection Genetics and Evolution, 2009Co-Authors: Sandeepa M Eswarappa, Jessin Janice, Sudhagar V Balasundaram, Narendra M Dixit, Dipshikha ChakravorttyAbstract:In this study, we have identified the possible genetic factors responsible for fowl-adaptation of Salmonella enterica serovar Gallinarum (S. Gallinarum). By comparing the genes related to Salmonella pathogenicity islands (SPI) of S. Gallinarum with those of Salmonella enterica serovar Enteritidis (S. Enteritidis) we have identified twenty-four positively selected genes. Our results suggest that the genes encoding the structural components of SPI-2 encoded type three secretion apparatus (TTSS) and the effector proteins that are secreted via SPI-1 encoded TTSS have evolved under positive selection pressure in these serovars. We propose that these positively selected genes play important roles in conferring different host-specificities to S. Gallinarum and S. Enteritidis.
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lac repressor is an antivirulence factor of Salmonella enterica its role in the evolution of virulence in Salmonella
PLOS ONE, 2009Co-Authors: Sandeepa M Eswarappa, Guruswamy Karnam, Arvindhan G Nagarajan, Sangeeta Chakraborty, Dipshikha ChakravorttyAbstract:The genus Salmonella includes many pathogens of great medical and veterinary importance. Bacteria belonging to this genus are very closely related to those belonging to the genus Escherichia. lacZYA operon and lacI are present in Escherichia coli, but not in Salmonella enterica. It has been proposed that Salmonella has lost lacZYA operon and lacI during evolution. In this study, we have investigated the physiological and evolutionary significance of the absence of lacI in Salmonella enterica. Using murine model of typhoid fever, we show that the expression of LacI causes a remarkable reduction in the virulence of Salmonella enterica. LacI also suppresses the ability of Salmonella enterica to proliferate inside murine macrophages. Microarray analysis revealed that LacI interferes with the expression of virulence genes of Salmonella pathogenicity island 2. This effect was confirmed by RT-PCR and Western blot analysis. Interestingly, we found that SBG0326 of Salmonella bongori is homologous to lacI of Escherichia coli. Salmonella bongori is the only other species of the genus Salmonella and it lacks the virulence genes of Salmonella pathogenicity island 2. Overall, our results demonstrate that LacI is an antivirulence factor of Salmonella enterica and suggest that absence of lacI has facilitated the acquisition of virulence genes of Salmonella pathogenicity island 2 in Salmonella enterica making it a successful systemic pathogen.
Sangwei Lu - One of the best experts on this subject based on the ideXlab platform.
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identification of genes associated with survival of Salmonella enterica serovar enteritidis in chicken egg albumen
Applied and Environmental Microbiology, 2006Co-Authors: Raul I Clavijo, Cindy Loui, Gary L Andersen, Lee W Riley, Sangwei LuAbstract:Salmonella enterica consists of over 2,000 serovars that are major causes of morbidity and mortality associated with contaminated food. Despite similarities among serovars of Salmonella enterica, many demonstrate unique host specificities, epidemiological characteristics, and clinical manifestations. One of the unique epidemiological characteristics of the serovar Enteritidis is that it is the only bacterium routinely transmitted to humans through intact chicken eggs. Therefore, Salmonella enterica serovar Enteritidis must be able to persist inside chicken eggs to be transmitted to humans, and its survival in egg is important for its transmission to the human population. The ability of Salmonella enterica serovar Enteritidis to survive in and transmit through eggs may have contributed to its drastically increased prevalence in the 1980s and 1990s. In the present study, using transposon-mediated mutagenesis, we have identified genes important for the association of Salmonella enterica serovar Enteritidis with chicken eggs. Our results indicate that genes involved in cell wall structural and functional integrity, and nucleic acid and amino acid metabolism are important for Salmonella enterica serovar Enteritidis to persist in egg albumen. Two regions unique to Salmonella enterica serovar Enteritidis were also identified, one of which enhanced the survival of a Salmonella enterica serovar Typhimurium isolate in egg albumen. The implication of our results to the serovar specificity of Salmonella enterica is also explored in the present study.
Sandeepa M Eswarappa - One of the best experts on this subject based on the ideXlab platform.
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host specificity of Salmonella enterica serovar gallinarum insights from comparative genomics
Infection Genetics and Evolution, 2009Co-Authors: Sandeepa M Eswarappa, Jessin Janice, Sudhagar V Balasundaram, Narendra M Dixit, Dipshikha ChakravorttyAbstract:In this study, we have identified the possible genetic factors responsible for fowl-adaptation of Salmonella enterica serovar Gallinarum (S. Gallinarum). By comparing the genes related to Salmonella pathogenicity islands (SPI) of S. Gallinarum with those of Salmonella enterica serovar Enteritidis (S. Enteritidis) we have identified twenty-four positively selected genes. Our results suggest that the genes encoding the structural components of SPI-2 encoded type three secretion apparatus (TTSS) and the effector proteins that are secreted via SPI-1 encoded TTSS have evolved under positive selection pressure in these serovars. We propose that these positively selected genes play important roles in conferring different host-specificities to S. Gallinarum and S. Enteritidis.
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lac repressor is an antivirulence factor of Salmonella enterica its role in the evolution of virulence in Salmonella
PLOS ONE, 2009Co-Authors: Sandeepa M Eswarappa, Guruswamy Karnam, Arvindhan G Nagarajan, Sangeeta Chakraborty, Dipshikha ChakravorttyAbstract:The genus Salmonella includes many pathogens of great medical and veterinary importance. Bacteria belonging to this genus are very closely related to those belonging to the genus Escherichia. lacZYA operon and lacI are present in Escherichia coli, but not in Salmonella enterica. It has been proposed that Salmonella has lost lacZYA operon and lacI during evolution. In this study, we have investigated the physiological and evolutionary significance of the absence of lacI in Salmonella enterica. Using murine model of typhoid fever, we show that the expression of LacI causes a remarkable reduction in the virulence of Salmonella enterica. LacI also suppresses the ability of Salmonella enterica to proliferate inside murine macrophages. Microarray analysis revealed that LacI interferes with the expression of virulence genes of Salmonella pathogenicity island 2. This effect was confirmed by RT-PCR and Western blot analysis. Interestingly, we found that SBG0326 of Salmonella bongori is homologous to lacI of Escherichia coli. Salmonella bongori is the only other species of the genus Salmonella and it lacks the virulence genes of Salmonella pathogenicity island 2. Overall, our results demonstrate that LacI is an antivirulence factor of Salmonella enterica and suggest that absence of lacI has facilitated the acquisition of virulence genes of Salmonella pathogenicity island 2 in Salmonella enterica making it a successful systemic pathogen.
Elena Bolchacova - One of the best experts on this subject based on the ideXlab platform.
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genome sequencing reveals diversification of virulence factor content and possible host adaptation in distinct subpopulations of Salmonella enterica
BMC Genomics, 2011Co-Authors: Henk Den C Bakker, Andrea Moreno I Switt, Gregory Govoni, Craig Cummings, M L Ranieri, Lovorka Degoricija, Karin Hoelzer, Lorraine D Rodriguezrivera, Stephanie Brown, Elena BolchacovaAbstract:Background Divergence of bacterial populations into distinct subpopulations is often the result of ecological isolation. While some studies have suggested the existence of Salmonella enterica subsp. enterica subclades, evidence for these subdivisions has been ambiguous. Here we used a comparative genomics approach to define the population structure of Salmonella enterica subsp. enterica, and identify clade-specific genes that may be the result of ecological specialization.
Henrik Caspar Wegener - One of the best experts on this subject based on the ideXlab platform.
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increasing quinolone resistance in Salmonella enterica serotype enteritidis
Emerging Infectious Diseases, 2002Co-Authors: Kare Molbak, Peter Gernersmidt, Henrik Caspar WegenerAbstract:Until recently, Salmonella enterica serotype Enteritidis has remained sensitive to most antibiotics. However, national surveillance data from Denmark show that quinolone resistance in S. Enteritidis has increased from 0.8% in 1995 to 8.5% in 2000. These data support concerns that the current use of quinolone in food animals leads to increasing resistance in S. Enteritidis and that action should be taken to limit such use.
