Systemic and mucosal immune responses in mice after mucosal immunization with group B streptococcus type III capsular polysaccharide-cholera term B subunit conjugate vaccine

Group B streptococci (GBS) colonize the female genital and rectal tracts an d can cause invasive infection in susceptible newborns.;in optimally effect ive GBS vaccine should induce mucosal and systemic immunity. In this study, we investigate the local and systemic immune responses to GBS type III cap sular polysaccharide (CPS) after mucosal vaccination of mice via intranasal , peroral, rectal, and vaginal routes, with GBS type III CPS conjugated wit h recombinant cholera toxin B subunit (GBS III CPS-rCTB), Cholera toxin (CT ) was added as an adjuvant, Immunoglobulin G (IgG) and IgA antibodies to th e CPS were tested in serum, lungs, and intestinal, rectal, and vaginal extr acts by enzyme-linked immunosorbent assay. The conjugated CPS administered by intranasal, peroral, rectal, and vaginal routes was much more effective at inducing both mucosal and systemic antibody responses to GBS III CPS tha n was unconjugated CPS. The CPS-specific immune responses in various organs were dependent on the route of immunization, Generally, the highest levels of IgA and IgG were generated in the regions or sites of the conjugate exp osure. Thus, intranasal vaccination elicited the highest anti-CPS IgA and I gG antibody levels in the lungs, whereas peroral administration in the inte stinal site and vaginal vaccination elicited the highest antibody levels in the vagina. Rectal vaccination was superior to the other routes in inducin g high antibody levels in the rectum, The four routes of mucosal vaccinatio n also induced distant antibody responses to CPS, Rectal vaccination induce d high specific IgA levels in the vagina and intestine, and oral administra tion induced high specific IgA levels in the lungs and rectum. All four rou tes of vaccination with the conjugate elicited similarly high levels of ant i-CPS IgG in serum, Intranasal vaccination with different doses of the conj ugate (10, 30, and 80 mu g of CPS) did not have a significant influence on the anti-CPS specific antibody responses. Intranasal immunization induced b etter antibody responses when one dose of the conjugate was divided and giv en on three consecutive days compared to administration of the full dose on one occasion. In conclusion, rectal and vaginal vaccination may be the bes t way of stimulating anti-CPS immune responses in the rectal and vaginal tr acts, while high levels of anti-CPS antibodies in the lungs can be achieved after intranasal administration. The vaccination regimen thus might influe nce the mucosal immune response to CPS, This conjugate may serve as an effe ctive mucosal vaccine for preventing mucosal colonization and invasive infe ction caused by GBS.