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Evaluation of serum bactericidal activity specific for Neisseria meningitidis serogroup A and B: effect of immunisation with N. meningitidis serogroup A polysaccharide and serogroup B outer membrane vesicle conjugate as a bivalent vaccine candidate

Abstract number: 1733_585

Adibi Motlagh B., Siadat S.D., Behzadiyannejad Q., Tabaraiee B., Ahmadi H., Najar Peerayeh S., Nourouzian Shamasbi D., Nejati M., Hedayati M.H., Moshiri A.

Objective: Bacterial meningitis caused by different groups of Neisseria meningitidis is still one of the Serious health problems world wide. The serum bactericidal assay (SBA) to meningococci is the most important test in immunological evaluation of meningococcal infection after vaccination. The SBA has been adapted as the gold standard for immunity against different serogroups of Neisseria meningitides after immunisation.

Methods:Neisseria meningitidis serogroup A capsular polysaccharide (CPSA) was conjugated to serogroup B OMV-PorA in order to test the possibility of obtaining a bivalent serogroup A and B meningococcus immunogen. The conjugate was prepared with adipic acid hydrazid (ADH) and 1-ethyl-3-(3-dimethylamino-propyl)carbodiimide (EDAC). The conjugate and control were injected intramuscularlly into groups of five rabbit with boosters on days 14, 28 and 42 after the primary immunisation. The following groups were used as control: (1) CPSA plus OMV-PorA; (2) CPSA; (3) OMV-PorA; and (4) normal saline. The serum collected on days 0, 14, 28, 42 and 56 were tested by complement mediated bactericidal assay according to the World Health Organization protocol.

Results: The results of SBA in the glycoprotein conjugate group revealed a significant increase in serum bactericidal titer against serogroup A meningococci after 56 day in comparison with the CPSA and OMV-PorA control group. Bactericidal titer against serogroup B meningococci of the conjugate showed no significant difference in comparison with the OMV-PorA containing control.

Conclusion: The results indicate that when polysaccharide A and OMV are in a covalent conjugate form, the complex is able to induce a high level of bactericidal antibody response. Therefore, this paper shows that the CPSA–OMV-PorA conjugate could be a candidate for bivalent Vaccine toward serogroup A and B meningococci.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Subject:
Location: ICC, Munich, Germany
Presentation type:
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