Figure 1.

GBS interaction with fibrinogen and contribution of Srr to reproductive tract adherence. A, GBS clinical isolates (n = 40) from vaginal tract of pregnant women and invasive isolates A909, 515, H36B, COH1, and NCTC 10/84 (n = 5) were incubated on 96-well microtiter plates coated with immobilized fibrinogen (0.4 µM). Srr allele status was determined by PCR as described in Materials and Methods. B, Representative GBS serotypes Ia, Ib, III, and V and isogenic Δsrr mutants were incubated with immobilized fibrinogen as in (A). Statistical comparisons were made between mutant and parental strains. C, Adherence of WT GBS and isogenic Δsrr mutants to hVECs at an MOI of 1. Total adherence values, percentage, of parental strains compared to original inoculum are indicated in parentheses. Statistical comparisons were made between mutant and parental strains. D–F, Adherence of WT NCTC 10/84 or isogenic Δsrr1 to hVEC, ecto-, or endocervical cells (MOI of 1) with or without blocking by antifibrinogen antibody (10 µg/mL). Values are expressed as the relative total of cell-associated CFUs recovered compared to original inoculum. Experiments were repeated at least twice with 4 replicates, and data from a representative experiment are shown. Data were analyzed by Student t test. *P < .05; **P < .005; ***P < .001. Abbreviations: CFUs, colony-forming units; CSF, cerebral spinal fluid; GBS, group B streptococcus; hVECs, human vaginal epithelial cells, MOI, multiplicity of infection; PCR, polymerase chain reaction; srr, serine-rich repeat gene; WT, wild type.