Group B Streptococcus serotypes Ia and V induce differential vaginal immune responses that may contribute to long term colonization of the female reproductive tract.

Group B Streptococcus (GBS) is a common colonizer of the female genital tract at the time of pregnancy and has been associated with severe neonatal infections. Despite trials for GBS vaccines already being underway, the factors influencing vaginal GBS colonization and clearance are currently poorly understood. Within this study, we investigated the host immune responses to GBS infections in mice that affect GBS vaginal colonization and clearance. Cervicovaginal swabs were used to measure vaginal GBS persistence, and vaginal cytokine responses were measured using the BioPlex® system. Lymphocytes isolated from spleens were stimulated with UV-killed GBS to examine systemic cellular responses. Additional in vitro cellular experiments using human vaginal epithelial cells were also performed, examining the effect pregnancy level hormones had on GBS adhesion, invasion, and cytokine responses. We observed significant differences in the ability of GBS serotype V infections to persist, compared with GBS serotype Ia vaginal infections. Vaginal cytokine response examination identified temporal changes in cytokine production (IL10, IFNγ, IL6, IL1β, and TNFα) in relation to GBS serotype and clearance or colonization. Lymphocyte proliferation assays also revealed robust cellular immune responses to GBS vaginal infections irrespective of clearance or colonization. In vitro human cellular analyses also identified that vaginal epithelial cell line cytokine production was suppressed in the presence of hormones despite no alteration in adhesion/invasion. Here, we establish previously unknown, serotype specific, temporal immune responses which may be associated with vaginal GBS colonization or clearance in the female genital tract.

Sweeney EL ，Gardiner S ，Tickner J ，Trim L ，Beagley KW ，Carey AJ ... -  《-》

Infection and cellular defense dynamics in a novel 17β-estradiol murine model of chronic human group B streptococcus genital tract colonization reveal a role for hemolysin in persistence and neutrophil accumulation.

Carey AJ ，Tan CK ，Mirza S ，Irving-Rodgers H ，Webb RI ，Lam A ，Ulett GC ... -  《-》

Serotype-specific acquisition and loss of group B streptococcus recto-vaginal colonization in late pregnancy.

Kwatra G ，Adrian PV ，Shiri T ，Buchmann EJ ，Cutland CL ，Madhi SA ... -  《PLoS One》

Mucosal vaccination promotes clearance of Streptococcus agalactiae vaginal colonization.

Group B Streptococcus (GBS) is a leading cause of morbidity and mortality in infants, and colonization of the maternal genital tract is the primary risk factor for newborn infection. Despite the importance of mucosal colonization in GBS pathogenesis, relevant host and bacterial factors are incompletely understood. We investigated the role of humoral immunity in clearance of vaginal colonization in vivo. B-cell-deficient mice or those lacking neonatal Fc-receptor, a mediator of IgG transport to the vaginal mucosa, exhibit prolonged GBS vaginal colonization compared to wild type animals. Intranasal but not intramuscular immunization induced systemic and mucosal immune responses and decreased GBS colonization duration without altering initial colonization density. Vaccine-induced clearance of GBS was serotype-specific, suggesting a role for anti-capsule antibodies in protection. Our results support a role for humoral immunity in GBS eradication from the female genital tract and suggest that mucosal vaccination may prime colonization clearance.

Baker JA ，Lewis EL ，Byland LM ，Bonakdar M ，Randis TM ，Ratner AJ ... -  《-》

Characterization of host immunity during persistent vaginal colonization by Group B Streptococcus.

Patras KA ，Rösler B ，Thoman ML ，Doran KS ... -  《-》