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dc.contributor.advisorPeter A. Rice, M.D.
dc.contributor.advisorSanjay Ram, M.D.
dc.contributor.authorDutta Ray, Tathagat
dc.date2022-08-11T08:08:43.000
dc.date.accessioned2022-08-23T16:05:10Z
dc.date.available2022-08-23T16:05:10Z
dc.date.issued2010-07-23
dc.date.submitted2011-02-01
dc.identifier.doi10.13028/kwp1-3r83
dc.identifier.urihttp://hdl.handle.net/20.500.14038/31829
dc.description.abstractN. meningitidis is a common commensal of the human upper respiratory tract and a leading cause of bacterial meningitis and septicemia worldwide. The classical pathway of complement (C) is essential for both naturally acquired and vaccine induced immunity against N. meningitidis. Qualitative and/or quantitative differences in anti-meningococcal antibodies (Abs) in serum is one reason for variations in C-dependent bactericidal Ab activity among individuals. I showed that IgG isolated from select individuals could block killing of group B meningococci by Abs that were otherwise bactericidal. Ligand overlay immunoblots revealed that these blocking IgG Abs were directed against a meningococcal antigen called H.8, Killing of meningococci in reactions containing bactericidal mAbs and human blocking Abs was restored when blocking Ab binding to meningococci was inhibited (or competed for) using either synthetic peptides corresponding to H.8 or a non-blocking mAb against H.8. Further, genetic deletion of H.8 from target organisms abrogated blocking. The Fc region of the blocking IgG was required for blocking because F(ab)2 fragments alone generated by pepsin treatment were ineffective. Blocking required IgG glycosylation; deglycosylation of blocking IgG with peptide:N-glycanase (PNGase) eliminated blocking. C4 deposition mediated by a bactericidal mAb directed against a meningococcal vaccine candidate, called factor H-binding protein (fHbp), was reduced by blocking Ab. Anti-fHbp-mediated C4 deposition was unaffected, however, by deglycosylated blocking IgG. Although preliminary, our data suggests blocking of serum bactericidal activity by human anti-H.8 blocking antibody may require mannan-binding lectin (MBL), which itself is a complement activator. Also, whether MBL recruits a complement inhibitor(s) that facilitates blocking remains to be determined. In conclusion, we have identified H.8 as a meningococcal target for novel blocking antibodies that are commonly found in human serum. Blocking Ab may reduce the efficacy of meningococcal vaccines. We propose that outer membrane vesicle-containing meningococcal vaccines may be more efficacious if purged of subversive immunogens such as H.8.
dc.language.isoen_US
dc.rightsCopyright is held by the author, with all rights reserved.
dc.subjectNeisseria meningitidis
dc.subjectSerogroup B
dc.subjectMeningococcal Vaccines
dc.subjectAmino Acids, Peptides, and Proteins
dc.subjectBacteria
dc.subjectBacterial Infections and Mycoses
dc.subjectEnvironmental Public Health
dc.subjectImmunology and Infectious Disease
dc.subjectInvestigative Techniques
dc.subjectNervous System Diseases
dc.subjectPathological Conditions, Signs and Symptoms
dc.subjectTherapeutics
dc.titleNovel Complement Blocking Antibodies Against Serogroup B <em>N. meningitidis</em>: A Dissertation
dc.typeDoctoral Dissertation
dc.identifier.legacyfulltexthttps://escholarship.umassmed.edu/cgi/viewcontent.cgi?article=1495&amp;context=gsbs_diss&amp;unstamped=1
dc.identifier.legacycoverpagehttps://escholarship.umassmed.edu/gsbs_diss/495
dc.legacy.embargo2011-08-31T00:00:00-07:00
dc.identifier.contextkey1757020
refterms.dateFOA2022-08-27T05:48:55Z
html.description.abstract<p><em>N. meningitidis</em> is a common commensal of the human upper respiratory tract and a leading cause of bacterial meningitis and septicemia worldwide. The classical pathway of complement (C) is essential for both naturally acquired and vaccine induced immunity against <em>N. meningitidis</em>. Qualitative and/or quantitative differences in anti-meningococcal antibodies (Abs) in serum is one reason for variations in C-dependent bactericidal Ab activity among individuals. I showed that IgG isolated from select individuals could block killing of group B meningococci by Abs that were otherwise bactericidal. Ligand overlay immunoblots revealed that these blocking IgG Abs were directed against a meningococcal antigen called H.8, Killing of meningococci in reactions containing bactericidal mAbs and human blocking Abs was restored when blocking Ab binding to meningococci was inhibited (or competed for) using either synthetic peptides corresponding to H.8 or a non-blocking mAb against H.8. Further, genetic deletion of H.8 from target organisms abrogated blocking. The Fc region of the blocking IgG was required for blocking because F(ab)<sub>2</sub> fragments alone generated by pepsin treatment were ineffective. Blocking required IgG glycosylation; deglycosylation of blocking IgG with peptide:<em>N</em>-glycanase (PNGase) eliminated blocking. C4 deposition mediated by a bactericidal mAb directed against a meningococcal vaccine candidate, called factor H-binding protein (fHbp), was reduced by blocking Ab. Anti-fHbp-mediated C4 deposition was unaffected, however, by deglycosylated blocking IgG. Although preliminary, our data suggests blocking of serum bactericidal activity by human anti-H.8 blocking antibody may require mannan-binding lectin (MBL), which itself is a complement activator. Also, whether MBL recruits a complement inhibitor(s) that facilitates blocking remains to be determined. In conclusion, we have identified H.8 as a meningococcal target for novel blocking antibodies that are commonly found in human serum. Blocking Ab may reduce the efficacy of meningococcal vaccines. We propose that outer membrane vesicle-containing meningococcal vaccines may be more efficacious if purged of subversive immunogens such as H.8.</p>
dc.identifier.submissionpathgsbs_diss/495
dc.contributor.departmentMedicine
dc.description.thesisprogramImmunology and Microbiology


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