Role of cellular lipoteichoic acids in mediating adherence of serotype III strains of group B streptococci to human embryonic, fetal, and adult epithelial cells

Abstract

Lipoteichoic acids (LTA) of serotype III strains of group B streptococci (GBS) were shown to mediate adherence of these organisms to human embryonic (HEC), fetal (HFC), and adult buccal (HBEC) epithelial cells. The binding of GBS was temperature dependent, and maximum attachment occurred at 37°C. HEC, HFC, and HBEC preincubated with purified LTA significantly inhibited attachment of GBS, whereas the group B and type III antigens had no effect. Under phosphate-limiting conditions in which cell-associated LTA could not be detected in these organisms, bacterial adherence did not take place. GBS (virulent) that were isolated from infected infants and previously shown to have significantly higher quantities of cellassociated LTA in comparison to GBS strains from asymptomatically colonized infants adhered with greater binding avidity to HEC and HFC and in greater numbers than to HBEC. It was determined that the mechanism of LTA-mediated adherence of GBS to HBEC differed from adherence to embryonic and fetal cells for both virulent and asymptomatic GBS strains bound to HBEC in a similar manner, enhanced by the lipid portion of the LTA. In contrast, the binding of GBS to HEC and HFC was mediated by hydrophobic as well as specific interactions due to the glycerolphosphate polymer of LTA. These results indicate that possible receptor sites for LTA present on cells in prenatal stages of development may differ from those of adult cells, which may result in increased susceptibility of newborn infants to group B streptococcal disease. The implications of LTA-mediated adherence of GBS and their possible role as virulence factors are discussed.

Comparative analysis of the localization of lipoteichoic acid in Streptococcus agalactiae and Streptococcus pyogenes

“…Age-related susceptibility to diseases caused by GAS has been suggested by the findings of Ofek et al (12), which demonstrated that LTA-mediated attachment of GAS to adult epithelial cells was 10-fold higher than that in neonatal cells. Conversely, Nealon and Mattingly (10) showed that GBS isolated from infected infants bound more avidly to human embryonic and fetal epithelial cells than to adult cells, and the specificity was attributable to long-chain molecules of LTA (11). The model for the participation of LTA in mediating attachment of GAS to epithelial cells requires the release of LTA from the cytoplasmic membrane and subsequent orientation at the cell surface with the fatty acid moieties available for interaction with hydrophobic domains on the surface of the epithelial cell (13).…”

“…Previous studies have indicated that lipoteichoic acids (LTA) play a major role in the adherence of serotype III strains of group B streptococci (GBS) to human embryonic and fetal epithelial cells (10). An initial binding phase occurred within the first 10 min after the addition of bacteria and appeared to be hydrophobic in nature (11).…”

Attachment of group B streptococci to macrophages is mediated by a 21-kDa protein

“…However, 100% inhibition with the antiserum was not achieved, suggesting that there are additional interactions between GBS and U937 cells. This is supported by work of Nealson and Mattingly [7] who showed that puri¢ed LTA was able to signi¢cantly inhibit adherence of GBS to embryonic cells. Because 100% inhibition could not be achieved, they suggested that attachment is most likely a multi-step process and that other receptors are involved.…”

The Group B Streptococcal C5a Peptidase Is Both a Specific Protease and an Invasin

“…Investigations of lipoteichoic acid (LTA) and adherence are contradictory. Several reports implicated LTA in adherence by showing that preincubation of epithelial cells with soluble LTA at high concentrations inhibited attachment of GBS (20). Others, however, who employed similar concentrations of LTA, did not observe an inhibitory effect (1).…”