Intranasal Vaccine Effective in Murine Model.(group B Streptococcus vaccine)

2001 FEB 8 - (NewsRx.com) -- by Michelle Marble, staff medical writer -- Researchers in Sweden demonstrated the efficacy of a group B Streptococcus type III polysaccharide-cholera toxin B subunit conjugate intranasal vaccine in a preclinical murine model.

"Streptococcus group B (GBS) is usually carried asymptomatically in the vaginal tract of women and can be transferred to the newborn during parturition," wrote X.Z. Shen and colleagues, Gothenburg University. "Serum antibodies to the capsular polysaccharide (CL'S) can prevent invasive diseases, whereas immunity acting at the mucosal surface may be more important to inhibit the mucosal colonization of GBS and thus the risk of infection for the newborn.

"We prepared different GBS type III CPS-protein conjugate vaccines and evaluated their systemic and mucosal immunogenicity in mice," wrote the authors. "GBS type III CPS was conjugated to tetanus toxoid (TT) or recombinant cholera toxin B subunit (rCTB) either directly or to rCTB indirectly via TT."

The researchers conjugated the vaccines by three different methods: (1) they coupled CPS to TT with 1-ethyl-3 (3-dimethylaminopropyl)-carbodiimide (EDAC) were adipic acid dihydrazide (ADH) was used as a spacer; (2) they conjugated CPS with rCTB using reductive amination; or, (3) they used N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP) to bind rCTB to the TT of the CPS-TT conjugate.

They vaccinated mice with one of the three conjugates or with purified CPS by either subcutaneous (s.c.) or intranasal (in.) routes. They then measured antibodies to GBS III in the serum, lungs, and vagina via an enzyme-linked immunosorbent assay.

Results showed that all three CPS-protein conjugates were superior to unconjugated CPS in eliciting CPS-specific immune responses in serum and mucosal tissue extracts.

The results showed that when conjugates were administrated s.c., they only induced immunoglobulin E (IgE) responses in serum, lung, and vagina. Intranasal administration, however, elicited additional immunoglobulin A ...