Capsule-Mediated Immune Evasion: a New Hypothesis Explaining Aspects of Typhoid Fever Pathogenesis

The Salmonella enterica serotype Typhi regulator TviA reduces interleukin-8 production in intestinal epithelial cells by repressing flagellin secretion

“…The in vivo relevance of these observations is demonstrated by the finding that the presence of the viaB locus significantly reduces cytokine expression, neutrophil recruitment and fluid accumulation elicited by S. Typhi or S. Typhimurium in bovine-ligated ileal loops (Raffatellu et al, 2007). These data suggest that the viaB locus represents one of the genetic differences between S. Typhi and non-typhoidal Salmonella serotypes that account for the scarcity of neutrophils in intestinal infiltrates of typhoid fever patients (Raffatellu et al, 2006). The goal of this study was to determine by which mechanism the viaB locus reduces IL-8 production in human intestinal epithelial cells.…”

“…Infection of human colonic tissue explants with a nontyphoidal Salmonella serotype, S. Typhimurium, results in expression of the neutrophil chemoattractant interleukin (IL)-8, but this response is not observed during infection with S. Typhi (Raffatellu et al, 2005). These data illustrate that S. Typhi possesses virulence mechanisms that prevent the induction of host responses leading to neutrophil recruitment in the intestinal mucosa (Raffatellu et al, 2006).…”

“…A precise deletion of the viaB locus significantly increases IL-8 expression elicited by S. Typhi in polarized T84 monolayers and in human colonic biopsy samples (Raffatellu et al, 2005). These data identify the viaB locus as a S. Typhi-specific DNA region involved in reducing expression of neutrophil chemoattractants in human colonic tissue explants and in colonic epithelial cancer cells (Raffatellu et al, 2006).…”

Molecular Mechanisms of Salmonella Pathogenicity: Review

“…Özel lik le epi tel hüc re le ri ta ra fın dan üre ti len ke mokin in ter lö ki n-8 ara cı lı ğı ile mu ko zal boş luk ta nöt-ro fil bi ri ki mi nin teş vik edil di ği tes pit edil miş-tir. 12,21,22 Sal mo nel la ba ğır sak epi tel hüc re le ri ni geç-tik ten son ra, bir di ğer ba ğı şık lık sis te mi ele ma nı olan ve mu ko zal boş luk ta yer alan mak ro faj lar içi -ne gir mek te dir. Sis te mik en fek si yo na yol açan Salmo nel la se ro tip le ri mak ro pi no si toz yo lu ile mak ro faj içi ne gir mek te ve fa go si tin an ti bak te ri yel fonk si yon la rın dan kur tul ma sı nı sağ la yan vi rü lans me ka niz ma la rı ak ti ve et mek te dir.…”

SPI-7: Salmonella’s Vi-Encoding Pathogenicity Island

“…Much effort has gone into the elucidation of the function of the Vi antigen, although the picture remains unclear. Its roles in pathogenesis and immune response are discussed in two reviews [30,31].…”