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Mostrando 13-24 de 34 artigos, teses e dissertações.
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13. Antibody response of monkeys to invasion plasmid antigen D after infection with Shigella spp.
The antigen preparation most often used for determining the levels of antibodies to virulence-associated proteins of Shigella spp. consists of a mixture of proteins (including IpaB, IpaC, IpaD, and VirG*) extracted from virulent shigellae with water (water extract). To overcome the lack of specificity for individual antigens in the water-extract enzyme-linke
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14. Nonpolar mutagenesis of the ipa genes defines IpaB, IpaC, and IpaD as effectors of Shigella flexneri entry into epithelial cells.
A 31-kb fragment of the large virulence plasmid of Shigella flexneri is necessary for bacterial entry into epithelial cells in vitro. One locus of this fragment encodes the IpaA, -B, -C, and -D proteins, which are the dominant antigens of the humoral immune response during shigellosis. To address the role of the ipa genes, which are clustered in an operon, w
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15. The secretion of the Shigella flexneri Ipa invasins is activated by epithelial cells and controlled by IpaB and IpaD.
Shigella species are enteropathogens that invade epithelial cells of the human colon. Entry into epithelial cells is triggered by the IpaB, IpaC and IpaD proteins which are translocated into the medium through the specific Mxi-Spa machinery. In vitro, Shigella cells secrete only a small fraction of the Ipa proteins, the majority of which remains in the cytop
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16. Nucleotide sequence and transcriptional regulation of a positive regulatory gene of Shigella dysenteriae.
A 1,937 bp PstI-HindIII fragment containing the ipaR locus was cloned from the large invasion plasmid of Shigella dysenteriae CG097, and its nucleotide sequence was completely determined. The IpaR protein (35 kDa, calculated from the DNA sequence) was synthesized in Escherichia coli chi 1411 minicells containing the 1,937-bp PstI-HindIII fragment. To determi
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17. Identification of two targets of the type III protein secretion system encoded by the inv and spa loci of Salmonella typhimurium that have homology to the Shigella IpaD and IpaA proteins.
An important virulence factor of Salmonella spp. is their ability to gain access to host cells. A type III secretion system encoded in the inv and spa loci of these organisms is essential for this phenotype. We have identified two proteins, SipA and SipD, whose secretion from the bacterial cells is dependent on this system. The genes encoding these proteins
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18. Disulfide oxidoreductase activity of Shigella flexneri is required for release of Ipa proteins and invasion of epithelial cells.
Secretion of IpaB, IpaC, and IpaD proteins of Shigella flexneri, essential for the invasion of epithelial cells, requires a number of proteins encoded by the spa and mxi loci on the large plasmid. Introduction of dsbA::Tn5 into S.flexneri from Escherichia coli K-12 reduced invasiveness, which resulted from a decrease in the capacity to release IpaB, IpaC, an
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19. Soluble invasion plasmid antigen C (IpaC) from Shigella flexneri elicits epithelial cell responses related to pathogen invasion.
Shigella flexneri invades colonic epithelial cells by pathogen-induced phagocytosis. The three proposed effectors of S. flexneri internalization are invasion plasmid antigens B (IpaB), IpaC, and IpaD, which are encoded on the pathogen's 230-kb virulence plasmid and translocated to the extracellular milieu via the Mxi-Spa translocon. To date, there are no def
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20. SYNTHETIC SPECTROSCOPIC MODELS RELATED TO COENZYMES AND BASE PAIRS, IV. STACKING INTERACTIONS IN TRNA; THE ANTICODON-ADJACENT BASE*
In order to test the Fuller and Hodgson hypothesis that modification of the anticodon-adjacent base in certain tRNA's not only prevents mRNA base-pairing at that site but also increases the stabilization of a stacked conformation in the anticodon loop, we have examined the interaction between adenosine and its N6-isopentenyl derivative by means of model comp
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21. Isolation and Characterization of a Shigella flexneri Invasin Complex Subunit Vaccine
The invasiveness and virulence of Shigella spp. are largely due to the expression of plasmid-encoded virulence factors, among which are the invasion plasmid antigens (Ipa proteins). After infection, the host immune response is directed primarily against lipopolysaccharide (LPS) and the virulence proteins (IpaB, IpaC, and IpaD). Recent observations have indic
American Society for Microbiology.
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22. Molecular cloning of invasion plasmid antigen (ipa) genes from Shigella flexneri: analysis of ipa gene products and genetic mapping.
Tn5-tagged invasion plasmid DNA (pWR110) from Shigella flexneri serotype 5 (strain M90T) was cloned into the expression vector lambda gt11. Recombinant phage (lambda gt11Sfl) expressing pWR110-encoded polypeptide antigens were identified by using rabbit antisera directed against S. flexneri M90T invasion plasmid antigens. Antigens encoded by lambda gt11Sfl r
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23. Contact of Shigella with host cells triggers release of Ipa invasins and is an essential function of invasiveness.
The invasion of colonic epithelial cells by Shigella, an early essential step for causing bacillary dysentery, is mediated by the IpaB, IpaC and IpaD proteins. Secretion of the Ipa proteins from Shigella requires functions encoded by the mxi and spa loci. In this study, we show that contact between the bacteria and epithelial cell triggers release of the Ipa
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24. Use of Shigella flexneri ipaC and ipaH gene sequences for the general identification of Shigella spp. and enteroinvasive Escherichia coli.
The products of the ipaB, ipaC, and ipaD genes are involved in the expression of the invasive phenotype in all species of Shigella and enteroinvasive Escherichia coli (EIEC). DNA probes derived from these genes are accurate indicators of the invasive phenotype (M. Venkatesan, J. M. Buysse, E. V. Vandendries, and D. J. Kopecko, J. Clin. Microbiol. 26:261-266,