title: Preparation and characterization of group A meningococcal capsular polysaccharide conjugates and evaluation of their immunogenicity in mice.
abstract: Epidemic and endemic meningitis caused by group A Neisseria meningitidis remains a problem in sub-Saharan Africa. Although group A meningococcal capsular polysaccharide (GAMP) vaccine confers immunity at all ages, the improved immunogenicity of a conjugate and its compatibility with the World Health Organization's Extended Program on Immunization offers advantages over GAMP alone. Conjugates of GAMP bound to bovine serum albumin (BSA) were synthesized, characterized, and evaluated for their immunogenicities in mice. Two methods, involving adipic acid dihydrazide (ADH) as a linker, were used. First, ADH was bound to GAMP activated with cyanogen bromide (CNBr) or with 1-cyano-4(dimethylamino)-pyridinium tetrafluoroborate (CDAP) to form GAMP(CNBr)AH and GAMP(CDAP)AH. These derivatives were bound to BSA by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) to form GAMP(CNBr)AH-BSA and GAMP(CDAP)AH-BSA. Second, ADH was bound to BSA with EDC to form AHBSA. AHBSA was bound to activated GAMP to form GAMP(CNBr)-AHBSA and GAMP(CDAP)-AHBSA. The yield of GAMP(CDAP)-AHBSA (35 to 40%) was higher than those of the other conjugates (5 to 20%). GAMP conjugates elicited immunoglobulin G (IgG) anti-GAMP in all mice after three injections of 2.5 or 5.0 microg of GAMP: the geometric mean (GM) was highest in recipients of GAMP(CDAP)-AHBSA (11.40 enzyme-linked immunosorbent assay units). Although the difference was not statistically significant, the 5.0- microg dose elicited a higher GM IgG anti-GAMP than the 2.5- microg dose. Low levels of anti-GAMP were elicited by GAMP alone. GAMP(CDAP)-AHBSA elicited bactericidal activity roughly proportional to the level of IgG anti-GAMP.
authors.affiliation: Laboratory of Developmental and Molecular Immunity, National Institute of Child Health and Development, National Institutes of Health, Bethesda, Maryland 20892, USA. junz@mail.nih.gov
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Jin
authors.forename: Chiayung
authors.initials: C
authors.lastname: Chu
authors.forename: John B
authors.initials: JB
authors.lastname: Robbins
authors.forename: Rachel
authors.initials: R
authors.lastname: Schneerson
mesh_terms: D000272:Adipates; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001770:Blood Bactericidal Activity; D002417:Cattle; D003429:Cross Reactions; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007202:Indicators and Reagents; D022401:Meningococcal Vaccines / Q000008:administration & dosage / Q000302:isolation & purification; D051379:Mice; D009345:Neisseria meningitidis / Q000145:classification / Q000276:immunology*; D009570:Nitriles; D011135:Polysaccharides, Bacterial / Q000276:immunology* / Q000302:isolation & purification; D011726:Pyridinium Compounds; D012710:Serum Albumin, Bovine / Q000008:administration & dosage; D018074:Vaccines, Conjugate / Q000008:administration & dosage / Q000302:isolation & purification
chemical_list: D000272:Adipates; D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D007202:Indicators and Reagents; D022401:Meningococcal Vaccines; D009570:Nitriles; D011135:Polysaccharides, Bacterial; D011726:Pyridinium Compounds; D018074:Vaccines, Conjugate; C043226:meningococcal group A polysaccharide; D012710:Serum Albumin, Bovine; C067292:1-cyano-4-dimethylaminopyridinium; C010011:adipic dihydrazide