The mechanism by which group B Streptococcus (GBS) interacts with human cells and disrupts physiological processes is an intriguing area of investigation and continues to unfold. The aim of this study was to investigate the adherence and intracellular viability within endothelial ECV304 cells of GBS serotypes Ia, III and V isolates from patients and asymptomatic carriers. The GBS isolates from patients (GBS-Ia 90222-urine, GBS-III 90356-liquor and GBS-V 90186-blood strains) exhibited a more efficient adherence and survival mechanisms to endothelial cells than those from asymptomatic carriers (GBS-Ia 85147-oropharynx, GBS-III 80340 and GBS-V 88641-vagina strains), independent of bacterial serotypes. Treatment of endothelial ECV304 cells with EDTA demonstrated that Ca2+-dependent molecules modulated the adherence and internalization process of GBS-Ia and III to ECV304 cells. SDS-PAGE analysis of samples of biotinylated ECV304 extracts treated with GBS clinical isolates (urine 90222-Ia, liquor 90356-III and blood 90186-V strains) revealed fragments ranging from ≈61 to ≈179 kDa. Results of immunoassays with ECV304 membrane proteins showed that ICAM-1 molecules interacted only with GBS-III liquor 90356 strain while β1 integrin interacted with GBS-III liquor 90356 and GBS-V blood 90186 invasive strains. Thus, the interaction between ICAM-1 and β1-integrin seems an additional means by which GBS exploits host endothelial cells during infection. These findings add to the current understanding of the roles played by multiple receptor-ligand systems in the uptake and pathogenesis of GBS infection.

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