Constraction of polyvalent anti-streptococcal vaccines and analysis of their polyvalent features
Abstract number: P1329
Meringova L.F., Ditina M.A., Wang A., Leontieva G.F., Grabovskaya K.B., Shen X.Z., Yang Y.H., Totolian A.A., Suvorov A.N.
Objectives: In many occasions when antibiotic prophylactics fails vaccination becomes the matter of choice. More studies have been made for streptococcal vaccine development. The most common approach for streptococcal vaccine generation is based on the obtaining the conjugates between the polyvalent protein antigens and polysaccharide capsule. This strategy provides both an immunogenicity, with significant protection and broad level of type specificity. The present work presents data on comparison of two variants of vaccines: one based on mixture of recombinant proteins and another on the conjugation of type III GBS (PS) capsular polysaccharide with GBS recombinant cell surface polypeptides.
Methods: Conjugation of polypeptides with PS was obtained by reductive amination. Immune response had been studied in mice (double immunisation with aluminum hydroxide as adjuvant). Antibody titer was tested by ELISA. Biological activity of antibodies was tested by opsonophagocytosis employing mice peritoneal macrophages.
Results: After optimisation of PS-peptides conjugation conditions (optimal concentration of the components, oxidation time, the temperature of reaction etc.) the best chemical reaction conditions for two of the recombinant polypeptides under study (P6 and ScaAB) were found. Vaccine preparations containing P6-PS or ScaAB-PS reacted with antibodies against each of the vaccine components which proved that the antigenic structure had been preserved. Covalent binding of the PS to P6 or ScaAB lead to the four fold increase of the immune response relatively mono peptides usage with maximum titers against P6 and ScaAB 1/13000 or 1/104000 concordantly. PS after the binding also was immunogenic which was proved by appearance of specific IgG which were detected up till 70 days after the immunisation. In case of the mixture of the peptides P6 and ScaAB the titer of specific antibodies against ScaAB-components was also increased as well as length of the antibody circulation 150 days. Mice antibodies obtained after immunisation with both type of vaccines were active against GBS belonging to different serotypes.
P6- and ScaAB-specific immune response (mixt vaccine and free form immunisation).
Conclusion: Usage of polyvalent vaccine preparations based on cell surface expressed recombinant polypeptides of GBS can dramatically increase their immunological features relatively to monovaccines.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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