| Purified polysaccharide and recombinant proteins were used to construct several glycoconjugate vaccines against B. mallei, a biowarfare agent. Intranasal immunization of horses with the capsular polysaccharide (CPS) and O-polysaccharide (OPS) glycoconjugates, CPS-ADH-SctF and OPS-ADH-SctF, did not increase anti-O-polysaccharide or anti-capsular polysaccharide serum or nasal wash titres above pre-immunization levels. Due to the low efficiency of the SctF carrier protein, other candidate proteins shared by B. pseudomallei and B. mallei were selected for comparison. Immunization of rats with OPS and CPS glycoconjugates made with SctF, ExoA, BPSL2062 and BPSS0357 demonstrated that SctF did not induce significant amounts of IgG antibodies to CPS and OPS in contrast to the ExoA, BPSL2062 and BPSS0357 carrier proteins. BPSS0357 was able to induce significant IgG antibody titres to CPS, OPS and the carrier protein. Several other candidate carrier proteins were found to be insoluble; however, they induced high titre responses in rats and may be suitable as future carrier proteins for new glycoconjugate vaccines. |
