ANTIBODY-RESPONSES IN SERUM AND LUNG TO INTRANASAL IMMUNIZATION WITH HAEMOPHILUS-INFLUENZAE TYPE-B POLYSACCHARIDE CONJUGATED TO CHOLERA-TOXIN-B SUBUNIT AND TETANUS TOXOID

Aim: Cholera toxin B subunit (CTB) has previously been used as a mucos al carrier for various vaccine candidate antigens. The objective of th is study was to see if coupling a bacterial polysaccharide, prior coup ling to tetanus toroid (TT), would improve the immunogenicity of HibCP S after nasal immunization. Methods: HibCPS was conjugated to CTB, TT or via TT to CTB, using glutaraldehyde or 1-ethyl-3(3-dimethylaminopro pyl)-carbodiimide (EDAC) and N-succinimidyl 3-(2-pyridyldithio) propio nate (SPDP). The conjugates were characterized and used for intranasal (IN) and subcutaneous (SC) immunizations of mice. The anti-Hib, -TT a nd -CTB antibody titers in serum and lungs after the immunizations wer e measured with ELISA. Results: The HibCTB was poorly immunogenic both given IN and SC compared with HibTT and HibTTCTB, probably because of inefficient coupling. In contrast, the conjugation of CTB to the HibT T conjugate resulted in a preparation which was superior both to the H ibTT and the HibCTB conjugates in inducing local IgA and IgG anti-HibC PS antibodies in the lungs. The anti-HibCPS serum IgG titers after IN immunization with the HibTTCTB conjugate were similar to the titers af ter IN immunization with HibTT, or SC immunization with a commercial H ibCRIM conjugate vaccine. In contrast to the other conjugates, the Hib TTCTB conjugate also gave rise to anti-Hib serum IgA titers. Conclusio n: We conclude that appropriate conjugation to CTB increases the mucos al immunogenicity of HibCPS, and that intranasal immunization with suc h a conjugate can give rise to both local and systemic anti-HibCPS ant ibody responses.