Adherence of group B Streptococci to human rectal and vaginal epithelial cell lines in relation to capsular polysaccharides as well as alpha-like protein genes - pilot study

Streptococcus agalactiae (Group B Streptococci, GBS) constitutes a risk factor for infections of the newborns born by colonized mothers. The adherence of GBS to epithelial cells has been proved to be an important factor in the colonization of mucus membranes of both human rectum and vagina. The objective of the study was to assess the adhesion of the selected GBS strains to the human colon adenocarcinoma cell line (HT-29) and human epidermoid vulvo-vaginal cells (A-431) in relation to the capsular polysaccharides and alpha-like protein genes. GBS strains from the human sources belonging to Ia, Ib, II, III and V serotypes possessing different surface alpha-like protein genes such as the alp 2, alp 3, bca, epsilon and rib in the conventional adherence assay were examined. The adherence of GBS strains to the HT-29 cell line was considerably higher than to the A-431 cell line. For GBS serotype Ia and III, a significant difference between the adhesion to the HT-29 and A-431 cell lines was presented. The adhesion of GBS strains to the HT-29 cell line depended on alpha-like protein genes. The most adhesive ones were the GBS strains containing the rib and alp 2 genes. The adherence of GBS strains to the A-431 cell line depended on both their serotype and alpha-like protein genes. Serotype III adhered to the A-431 cells most tightly, particularly the strains containing the rib and alp 2 genes. GBS strains containing the rib gene adhered to the HT-29 and A-431 cell lines more firmly than GBS strains containing other alpha-like protein genes.