Typhi in a humanized non-obese diabetic (NOD) severe combined immune deficient (SCID) mouse model ().
In the small intestine, bacteria move across the intestinal epithelial cell (CEI) and reach the M cells, thus penetrating in the Peyer's patches ().
The M cells are specialized epithelial cells overlying Peyer's patches that have probably originated from CEI and small pockets in the mucosal surface.
After contact with M cells, the infectious bacteria are rapidly internalized and they reach a group of antigen-presenting cells (APCs), being partially phagocytized and neutralized.
are distinguished from their non-pathogenic relatives by the presence of specific pathogenicity genes, often organized in so-called pathogenicity islands (PIs).
The type III secretion system (T3SS) proteins encoded by two PIs (SPIs) are associated with the pathogenicity at molecular level.
The identification of T3SS has provided new insight into the molecular factors and mechanisms underlying bacterial pathogenesis.The T3SS encoded by SPI-1 contains invasion genes; while SPI-2 is responsible for intracellular pathogenesis and has a crucial role for systemic ).Typhoid remains a major health problem, especially in developing world where there is substandard water supply and lack of sanitation ( Crum Cianflone, 2008, Bhunia et al., 2009, Crump and Mintz, 2010 and Dougan et al., 2011).Typhi is transmitted through contaminated food and water, following ingestion, the bacteria spread from the intestine via blood to the intestinal lymph nodes, liver, and spleen where they multiply.Significant morbidity and mortality is associated with this disease possibly affecting over 90 million people globally each year ( Typhi serotypes with resistance to multiple antibiotics and changing modes of bacterial presentation, typhoid fever is becoming increasingly difficult to diagnose and treat ( Feng, 2000, Akinyemi et al., 2005 and Yang et al., 2010). Typhoid is a systemic disease that varies in severity.Recently a novel model has been reported that allows analyses of the pathogenesis of S.