Immunogenicity Of Group A Meningococcal Polysaccharide And Recombinant HBsAg Conjugates In Mice

To investigate the possibility of recombinant HBsAg as a carrier protein .A conjugate of group A meningococcal capsular polysaccharide (GAMP) bound to the recombinant HBsAg expressed in CHO cell as a protein carrier were synthesized, characterized, and evaluated for the immunogenicity in mice comparing with the conjugate of GAMP to tetanus toxoid (TT) as the protein carrier.GAMP was activated with cyanogens bromide (CNBr) and GAMP-HBsAg conjugate was prepared using ADH as a linker and EDAC as a coupling agent. Then the conjugate was purified by ion-exchange chromatography. The immunoreactivity of the conjugate was detected by double immunodiffusion assay and ELISA. The ADH% and other biochemical indicators were measured. The antibodies against GAMP and carrier proteins in the serum of the immunized mice were determined. Serum titer was measured by indirect ELISA and the isotype of Ig was measured by double immunodiffusion assay.The results suggested that the ADH% of four lots of the conjugates were 2.04%,2.44%,1.67% and 2.21%. All the KD values of the conjugates were below 0.2. The titer of antibody induced by GAMP-TT specific to GAMP was 57.94EU .The GAMP-HBsAg induced high serum anti-GAMP IgG antibody level (10.76EU&27.43EU) comparing with GAMP alone (1.03EU). The positive conversion rate of GAMP-HBsAg was 100%. The results were statistically significant (t=2.378,t=6.572,P<0.05). The titer of antibody induced by GAMP-HBsAg specific to HBsAg was 58.5EU.From the results of experiment we conclude that by conjugating with HBsAg, the immunogenicity of GAMP could be significant improved. The antibody of HBsAg also induced by the conjugate in the serum. So the HBsAg could be used as a candidate carrier protein.