The objective of the present study is to purify oligosaccharides (OSs) from serogroup B meningococci (3407 or 542852) with common lipooligosaccharide (LOS) immunotypes prevalent in China and to successtully conjugate them to their outer membrane protein complexes (OMPCs).Conjugates possessing broad cross-reactivity with different serogroup B meningococci were obtained.Both LOSs from the above two strains were purified on a Sephghex G75 column and hydrolyzed with acetic acid, and then the pare OSs were obtained by using a Sephadex G50 chromatographic column. The pure OSs were conjugated to corresponding OMPCs by carbodiimide mediated condensation. Mice were immunized with the OS-OMPC conjugates to produce antibodies. Immunognicities of the conjugates were tested by EUSA, bactericidal test and Western-blotting. The titers of antibodies against OS and LOS elicited by the two OS-OMPC conjugates increased respectively by 2. 5and 2 to 10 times as compared with those of antibodies against unconjugated OS and LOS. The sera elicited by the conjugates possessed a stronger bactericidal activity to the stndus (3407, 542852,29021) with the same LOS immunotype than to the strain with different LOS immunotype (86155).The results determined by ELISA indicated that the sera against the conjugaes showed strong response to the strains with the same or different LOS immunotypes. It was confirmed by westem-blotting analysis that the sera elicited by the two conjugates reacted with 42, 39 and 26 kDa proteins from the OMPC. Among the reactive bands, the 42kDa proteins were class 1 OMPs. The two serogroup B meningococcal OMPCs were strong immunogens and good carriers coupling with OSs as well. The immunogencity of the conjugaed OS was increased and the OS-OMPC conjugates of the serogroup B meogingococci showed a broad antigenic response to the strains tested.
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