Biodegradable microspheres containing group B Streptococcus vaccine: Immune response in mice

OBJECTIVE: This study seeks to show the feasibility of producing a group B Streptococcus (GBS) vaccine, which is capable of producing both a local IgA immune response at the mucosal surface where GBS is Colonized and a humora l IgG response, which is capable of transplacental passive immunization. STUDY DESIGN: Inactivated GBS antigen was microencapsulated in poly (D, L-l actic-co-glycolic acid) (PLG) with a water-in-oil-in-water double emulsion technique. Immunostimulatory synthetic oligodeoxynucleotides containing cyt idine-phosphate-guanosine (CpG) motifs were coencapsulated as a potent adju vant. The ICR strain of mouse was used in these studies. Female mice with n ormal immune systems were immunized with the PLG microparticles containing GBS type III polysaccharide (GBS PS) vaccine and CpG adjuvant (PLG/GBS/CpG) via the oral, vaginal, or nasal routes or by the intramuscular or intraper itoneal routes. Booster doses were administered 4 weeks after the initial i mmunization. Vaginal washings and blood samples were obtained 3 weeks after the booster dose and examined for both IgG and secretory IgA (slgA) GBS an tibodies with the use of an enzyme-linked immunoabsorbent assay method. RESULTS: PLG/GBS/CpG microparticles elicited a significantly higher GBS ant ibody response when compared with nonencapsulated GBS antigen or PLG-encaps ulated GBS PS vaccine without the addition of the CpG adjuvant. IgG and sec retory IgA (slgA) antibodies to GBS antigen were documented in both the vag inal washings and blood samples,. CONCLUSION: Preliminary findings indicate that this novel PLG/GBS/CpG vacci ne elicited both IgA and IgG antibody responses to the GBS PS antigen studi ed. This antibody response may provide both protection against maternal GBS colonization and passive transplacental immunization for the fetus and neo nate.