The establishment of successful listerial infection requires the presence and expression of virulence genes, demonstrated in various growth media ( 9, 21). monocytogenes enters host cells either by phagocytosis or endocytosis, where it can infect adjacent cells, enter the bloodstream ( 7), and eventually infiltrate body organs such as the liver, spleen, and brain ( 2). monocytogenes to host intestinal cells is considered the first step in pathogenesis. monocytogenes pathogenicity can be attributed to its ability to penetrate, survive, and replicate in professional and nonprofessional phagocytes. Infection may also lead to abortion or stillbirth in pregnant women. Listeria monocytogenes is an invasive food-borne pathogen that affects immunocompromised individuals, the elderly, and children, causing severe diseases ranging from gastroenteritis to meningitis or encephalitis. In summary, nutrient-rich media and high concentrations of glucose suppressed LAP expression, which possibly is due to the changes in the pH of the media during growth from the accumulation of sugar fermentation by-products. Growth in LB with high glucose (3.2 g/liter) showed the presence of only a few molecules in the cells, corroborating the results observed with ELISA or immunoblotting. Transmission electron microscopy revealed that LAP is localized mainly in the cytoplasm, with only a few molecules located on the cell surface. monocytogenes strain (A572) showed low adhesion profiles regardless of the amount of glucose added. monocytogenes cells grown in LB with higher glucose concentrations exhibited lower adhesion (2,126 and 2,221 cpm for 1.6 and 3.2 g of glucose/liter, respectively). monocytogenes cells grown in LB media with lower concentrations of glucose showed higher adhesion to Caco-2 cells (3,716 and 4,186 cpm of attached bacteria for 0 and 0.2 g of glucose/liter, respectively), while L. ELISA and immunoblotting results showed that higher concentrations of glucose (>1.6 g/liter) lowered the culture pH and suppressed LAP expression by more than 75% however, the addition of K 2HPO 4 reduced this effect. Immunoblotting showed that LAP expression was at least twofold higher in LB medium than in TSB or BHI, while PW supported very poor cell growth and LAP expression. Also, the effect of incorporating different concentrations of glucose on LAP expression was studied. Here, the expression of the 104-kDa Listeria adhesion protein (LAP) was studied in nutrient-rich media (Trypticase soy broth and brain heart infusion ), minimal medium (Luria-Bertani ), or nutrient-deficient medium (peptone water ) by immunoblotting, enzyme-linked immunosorbent assay (ELISA), and immunoelectron microscopy. Growth media and environmental conditions influence the expression of adhesion and invasion proteins in Listeria monocytogenes.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |