Biological and immunological characteristics of a new lipopolysaccharide-based conjugate vaccine for brucellosis

Abstract number: P2029

Siadat S.D., Aghasadeghi M.R., Mohammadi M., Kheirandish M., Norouzian D., Izadi Mobarakeh J., Razavi M., Zangeneh M., Sadat S.M., Sharifat Salmani A., Moshiri A.

Objective: The development of an efficacious vaccine for brucellosis has been a challenge for scientists for many years. At present, there is no licensed vaccine against human brucellosis. To overcome this problem, currently, antigenic determinants of Brucella cell wall such as Lipopolysaccharide (LPS) are considered as potential candidates to develop subunit vaccines. Since naturally occurring strains lacking LPS show reduced survival, LPS is considered to be a major virulence factor. Also, the LPS of B. abortus is considered one of the most important antigens from the point of view of the primary targets of the innate immunity.

Methods: We have undertaken detoxified of Brucella abortus S99 LPS by basic hydrolysis and resultant amine groups were used for their conjugation to Neisseria meningitidis serogroup B outer membrane vesicle as carrier protein using carbodiimide and adipic acid-mediated coupling and linking respectively. Groups of ten Balb/c mice were injected intramuscularly with 5 mg of dLPS alone, combine or conjugated on 0, 14 and 28 days. Sera were taken before and 14 days after each injection. The anti-LPS IgM and IgG were measured in serum.

Results: The molar ratio (dLPS/OMV) of the resulting conjugate was 45:1. The dLPS-OMV conjugates was the most immunogenic compound that stimulated following the first injection an increase in IgG titre of about 9.50, 5.80 and 4.53 fold higher than that produced against LPS, LPS in non covalent complex to OMV (LPS+OMV) and LPS with complete Freund's adjuvants, respectively. The highest anti-LPS IgG titer was detected two weeks after the third injection (the day 42) of dLPS–MV conjugates.

Conclusion: Our previous studies demonstrated that LPS+OMV was immunogenic in mice and elicited high level of anti-LPS IgG titers. In this study, conjugation of LPS to OMV was designed and the antigenicity of this conjugated was evaluated by ELISA. The conjugated elicited higher titers of IgG than LPS+OMV, that showed a 120- to 165-fold rise of anti-LPS IgG in mice. These results indicate that the conjugated LPS obtained by us, can be used as a brucellosis vaccine after further investigation.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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