New meningococcal C polysaccharide-tetanus toxoid conjugate Physico-chemical and immunological characterization.

The polysaccharides (Ps) are thymus-independent 2 (TI-2) antigens and poor immunogens in infants and young children; as a result of this delayed response to Ps antigens during ontogeny, infants and young children are highly susceptible to infections caused by encapsulated bacteria. Meningococcal group C polysaccharide (PsC)-proteins conjugate vaccines have been reported to induce significant serum IgG antibodies and immunologic memory in infants resulting in very effective vaccines. We describe here the obtainment, by a new method, of a neoglycoconjugate intended to immunize against Neisseria meningitidis serogroup C, its characterization by physico-chemical methods, including (1)H NMR and fluorescence spectroscopy methods, as well as the characterization of the immune response induced in mice by such conjugate. Amine groups generated by basic hydrolysis in the PsC were successfully conjugated to carboxyl groups of tetanus toxoid (TT), using carbodiimide-mediated coupling. The specific anti-Ps IgG and anti-Ps IgG subclasses (IgG1 and IgG2a) were measured by ELISA methods, the bactericidal activity in sera and the cytokines response (IFNgamma or IL5) in spleen cell of mice immunized with conjugated and native Ps were evaluated. The (1)H NMR spectra and the result obtained by the fluorescence spectroscopy method showed that the PsC and TT maintained structural identity after conjugation process. Conjugated PsC elicited an increase of anti-PsC IgG responses, anti-PsC IgG subclass (IgG1, IgG2a), an eight-fold increase in bactericidal activity in sera of mice immunized with conjugate compared with native PsC, was also observed. Higher titres of IFNgamma were observed in mice immunized with conjugated Ps. These results indicated that, the PsC and TT maintained its chemical and antigenic structure after the conjugation process. A change in the immunological pattern of responses of PsC, from TI-2 to a thymus-dependent (TD) pattern, was also demonstrated.

Mucosal immune responses to meningococcal C polysaccharide-protein conjugate in mice.

Mucosal delivery of vaccines represents an attractive approach because this is a region of first contact point for inhaled antigens. We have obtained a meningococcal group C polysaccharide-tetanus toxoid conjugate (MGCP-TT) and evaluated it for intranasal route in mice. The conjugate was obtained by a developed method in our laboratory. The specific IgA in saliva and specific IgA and IgG in serum were measured by ELISA methods and bactericidal antibodies in sera against a meningococcal group C strain were measured. The conjugated elicited a significant increase in anti-MGCP salivary IgA and serum IgG and bactericidal antibodies concentrations, while specific serum IgA was not observed. These results indicated that after conjugation, there was a change in the responses for MGCP from thymus-independent to thymus-dependent and that it was effective by intranasal route.

Inmunogenicidad inducida por la vacuna antimeningocócica VA-MENGOC-BC® contra la cepa de N. meningitidis ATCC C11 en adolescentes después de 12 años de vacunados / Immunogenecity induced by the VA-MENGOC-BC® antimeningococcal vaccine against the ATCC C11 N. meningitidis strain in adolescents 12 years after being vaccinated

Se estudió la respuesta de anticuerpos inducida por la vacuna antimeningocócica cubana VA-MENGOC-BC® contra la cepa ATCC C11 mediante Ensayo Bactericida del Suero y ELISA, a 184 adolescentes de un Politécnico de Ciego de Ávila, que habían sido inmunizados en campañas masivas 12 años antes. Se realizaron extracciones de sangre antes de aplicar la primera dosis (T0), 4 semanas después de esta (T1) y 4 semanas después de la segunda dosis (T2). Después de 12 años de la vacunación, 25 por ciento de los adolescentes presentó títulos bactericidas ≥ 1:8 frente a la cepa evaluada. Por ELISA, 78 por ciento mostró una concentración de anticuerpos superior al límite de detección contra el polisacárido capsular del meningococo C. Los porcentajes de seroconversión posterior a la primera dosis fueron 59 por Ensayo Bactericida del Suero y 82 por ELISA. No hubo diferencias significativas (p> 0,05) entre los resultados obtenidos después de la primera y segunda dosis por ambos ensayos. La reinmunización con 2 dosis de la vacuna no provocó hiporrespuesta frente a la cepa ATCC C11 en este grupo de edad

[Immunogenecity induced by the VA-MENGOC-BC antimeningococcal vaccine against the ATCC C11. N. meningitidis strain in adolescents 12 years after being vaccinated]. / Inmunogenicidad inducida por la vacuna antimeningocócica VA-MENGOC-BC contra la cepa de N. meningitidis ATCC C11 en adolescentes después de 12 años de vacunados.

The antibodies' response induced by the VA-MENGOC-BC Cuban antimeningococcal vaccine against the ATCC C11 strain was studied by Bactericidal Serum Trial and ELISA among 184 adolescents from a polytechnic, in Ciego de Avila, that had been immnunized in mass campaings 12 years before. Blood samples were taken before administering the first dose (T0), 4 weeks later (T1), and 4 weeks after the second dose (T2). 12 years after vaccination, 25% of the adolescents presented bactericidal titers > or =1:8 against the evaluated strain. 78% showed a concentration of antibodies over the limit of detection against the meningococcus C capsular polyssacharide. The percentages of seroconversion after the first dose were 59 by Bactericidal Serum Trial and 82 by ELISA. There were no significant differences (p > 0.05) between the results obtained after the first and second dose by boths trials. The reimmnunization with 2 doses of the vaccine did not cause hyporesponse against the ATCC C11 strain in this age group.