IMMUNOGENICITY OF ACTINOBACILLUS-ACTINOMYCETEMCOMITANS SEROTYPE B-SPECIFIC POLYSACCHARIDE-PROTEIN CONJUGATE

To enhance the immunogenicity of capsular-like serotype b-specific pol ysaccharide antigen (SPA) of Actinobacillus actinomycetemcomitans, the purified antigen was coupled with bovine serum albumin via an adipic acid hydrazide functional group. The conjugate (SPA-bovine serum album in) or the native SPA was administered subcutaneously or intranasally to BALB/c mice. Neither subcutaneous immunization with SPA emulsified in Freund adjuvant nor intranasal immunization with SPA and cholera to xin B subunit elicited any antibody responses to the polysaccharide an tigen. High serum immunoglobulin M (IgM) and IgG responses to SPA were induced by subcutaneous immunization with SPA-bovine serum albumin in Freund adjuvant. Serum and salivary IgA responses to SPA in addition to IgM and IgG responses were induced by intranasal immunization with the conjugate and cholera toxin B subunit. To investigate the function al activity of SPA-specific antibodies, the opsonic activity of sera f rom BALB/c mice immunized with the conjugate was assessed by chemilumi nescence assay using human polymorphonuclear leukocytes. Murine antise ra efficiently opsonized A. actinomycetemcomitans serotype b in the as say, suggesting that antibodies to SPA of the organism might serve as a protective role.