Synthesis, Characterization and Immunological Properties of LPS-Based Conjugate Vaccine Composed of O-Polysaccharide from Pseudomonas aeruginosa IATS 10 Bound to Recombinant Exoprotein A.

Nareman F. Abu-baker, Hussein A. Masoud, Basem M. Jaber


©  2008 DAR Publishers/University of Jordan. All Rights Reserved.

Pseudomonas aeruginosa is an important opportunistic pathogen that can cause infection in immunocompromised patient. Lipopolysaccharide (LPS), the major surface antigen of P. aeruginosa, is immunogenic and elicits protective antibodies in animals. The O-polysaccharide (O-PS) from International Antigenic Typing Scheme (IATS) 10, the antigenic determinant of LPS, was coupled to recombinant exoprotein A (rEPA) through adipic acid dihydrazide (ADH) mediated by carbodiimide condensation reaction. Mice were immunized with the conjugate emulsified with monophosphoryl lipid A-trehalose dicorynomycolate (MPL-T) and Freund’s adjuvants. The conjugate emulsified with MPL-T adjuvant elicited the highest level of IgG and IgM followed by Freund’s adjuvant. IgG titers using both MPL-T and Freund’s adjuvants were recorded to be higher than IgM titers after the second post of the immunization. Immunization of mice with the prepared conjugates emulsified with MPL-T and Freund’s adjuvants provided high level of protection (100%) against ten times the LD50 of homologous strain of P. aeruginsoa. The elicited high IgG level and the in vivo protection test results provided good evidences for the possible protection of the conjugate against subsequent infection with the pathogen. These findings will enable us to use it as protective vaccine candidate.


Adjuvant, Conjugate Vaccine, Lipopolysaccharide, Pseudomonas aeruginosa

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