ABSTRACT
Surface exposed fibronectin-binding proteins (FBPs) play an important role in the adherence of Streptococcus pyogenes (group A streptococcus, GAS) to host cells. This pathogen expresses numerous FBPs, of which SfbI, SfbII and PrtF2 are major surface exposed FBPs. However, GAS strains differ in the genetic potential to express these proteins. To test whether this difference reflects in differences in fibronectin (Fn) binding, a set of circulating strains previously examined for adherence to host cells was used. The 68 distinct strains were isolated from throat, skin and blood. They were analyzed for (a) the presence of genes for SfbI, SfbII and PrtF2 and (b) the extent of Fn binding. The results suggest that strains possessing two or more of the genes for these FBPs bound Fn significantly more than strains possessing none or one of the genes. No correlation between the extent of Fn binding and the tissue site of isolation was found. Furthermore, together with our previous studies on adherence capacity of these GAS strains, we found no correlation between Fn binding ability and the avidity of the strains to adhere to epithelial cells. We suggest that while Fn binding is important for adhesion, for many GAS strains the extent of Fn binding is not the critical determinant of adherence.
Subject(s)
Bacterial Adhesion , Fibronectins/metabolism , Streptococcus pyogenes/pathogenicity , Adhesins, Bacterial/genetics , Bacterial Proteins/genetics , Blood/microbiology , Cell Line , Cell Line, Tumor , DNA, Bacterial/analysis , DNA, Bacterial/genetics , DNA, Bacterial/isolation & purification , Genes, Bacterial , Humans , Pharynx/microbiology , Protein Binding , Skin/microbiology , Streptococcal Infections/microbiology , Streptococcus pyogenes/genetics , Streptococcus pyogenes/isolation & purificationABSTRACT
Streptococcus pyogenes (group A streptococcus, GAS) is a human-specific pathogen, which employs a large number of adhesins for colonization. Fibronectin-binding proteins (FBPs) play a major role in GAS adhesion to host cells. SfbI, a major streptococcal FBP, has been well studied. A peptide (peptide-MSG) based on this adhesin inhibits fibronectin (Fn)-binding by the pathogen. To test whether this peptide also inhibits adherence of GAS to host cells, adhesion assays were performed with strains possessing different combinations of genes for three distinct FBPs. Peptide-MSG inhibited GAS adherence to human keratinocytes (HaCaT) in a strain dependent manner. There is no consistent pattern between the effect and the ability to express one or more of the FBPs. A single peptide may be insufficient to prevent GAS adherence to host cells.
Subject(s)
Adhesins, Bacterial/pharmacology , Bacterial Adhesion/drug effects , Streptococcus pyogenes/drug effects , Amino Acid Sequence , Bacterial Adhesion/physiology , Cell Line , Fibronectins/physiology , Humans , Molecular Sequence Data , Peptide Fragments/pharmacology , Streptococcus pyogenes/physiologyABSTRACT
Epidemiologically unrelated Streptococcus pyogenes strains isolated from blood, throat, and skin were assayed for adherence to HEp2 and HaCaT cells. Invasive isolates showed significantly higher avidity for these cell lines than isolates from skin and throat. In general, S. pyogenes showed greater binding to HaCaT cells than to HEp2 cells.
