title: Human Complement Bactericidal Responses to a Group A Meningococcal Conjugate Vaccine in Africans and Comparison to Responses Measured by 2 Other Group A Immunoassays.
abstract: BACKGROUND
  PsA-TT (MenAfriVac) is a conjugated polysaccharide vaccine developed to eliminate group A meningococcal disease in Africa. Vaccination of African study participants with 1 dose of PsA-TT led to the production of anti-A polysaccharide antibodies and increased serum bactericidal activity measured using rabbit complement (rSBA). Bactericidal responses measured with human complement (hSBA) are presented here.
  
  
  METHODS
  Sera collected before and at 28 days and 1 year after vaccination with either PsA-TT or quadrivalent polysaccharide vaccine (PsACWY) from a random, age-distributed 360-subject subset of the Meningitis Vaccine Project study of PsA-TT in Africans aged 2-29 years were tested for hSBA. Geometric mean titer, fold-rise, and threshold analyses were compared between vaccine groups and age groups. hSBA, rSBA, and immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) results were compared and assay correlation and agreement determined.
  
  
  RESULTS
  hSBA responses to PsA-TT were substantially higher than those to PsACWY at 28 days and 1 year following immunization, similar to previously reported rSBA and IgG results. The hSBA and IgG ELISA results identified differences between age groups that were not evident by rSBA. The rSBA data indicated sustained high titers 1 year after immunization, whereas hSBA GMTs at 1 year approached 4 in young children.
  
  
  CONCLUSIONS
  The high level of protection following PsA-TT immunization campaigns is consistent with the strong hSBA immune responses observed here. Future implementation decisions will likely depend on immunologic data and their long-term correlation with disease and carriage prevention. Expanded immunologic and epidemiologic surveillance may improve the interpretation of differences between these immunoassays.
authors.affiliation: Laboratory of Bacterial Polysaccharides, Division of Bacterial, Parasitic, and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Price
authors.affiliation: Laboratory of Bacterial Polysaccharides, Division of Bacterial, Parasitic, and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland.
authors.forename: Aimee M
authors.initials: AM
authors.lastname: Hollander
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Plikaytis
authors.affiliation: Laboratory of Bacterial Polysaccharides, Division of Bacterial, Parasitic, and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland.
authors.forename: Brian T
authors.initials: BT
authors.lastname: Mocca
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: George
authors.initials: G
authors.lastname: Carlone
authors.affiliation: Vaccine Evaluation Unit, Public Health England, Manchester Royal Infirmary, United Kingdom.
authors.forename: Helen
authors.initials: H
authors.lastname: Findlow
authors.affiliation: Vaccine Evaluation Unit, Public Health England, Manchester Royal Infirmary, United Kingdom.
authors.forename: Ray
authors.initials: R
authors.lastname: Borrow
authors.affiliation: Centre pour le Développement des Vaccins, Ministère de la Santé, Bamako, Mali.
authors.forename: Samba O
authors.initials: SO
authors.lastname: Sow
authors.affiliation: Institut de Recherche pour le Développement, Niakhar, Senegal.
authors.forename: Aldiouma
authors.initials: A
authors.lastname: Diallo
authors.affiliation: Vaccines and Immunity Theme, Medical Research Council Unit, Basse, The Gambia.
authors.forename: Olubukola T
authors.initials: OT
authors.lastname: Idoko
authors.affiliation: Meningitis Vaccine Project, PATH, Ferney-Voltaire, France.
authors.forename: Godwin C
authors.initials: GC
authors.lastname: Enwere
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Cheryl
authors.initials: C
authors.lastname: Elie
authors.affiliation: Meningitis Vaccine Project, PATH, Ferney-Voltaire, France Meningitis Vaccine Project, Department of Immunization, Vaccines and Biologicals, World Health Organization, Geneva, Switzerland.
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Preziosi
authors.affiliation: Serum Institute of India Ltd, Pune.
authors.forename: Prasad S
authors.initials: PS
authors.lastname: Kulkarni
authors.affiliation: Laboratory of Bacterial Polysaccharides, Division of Bacterial, Parasitic, and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland.
authors.forename: Margaret C
authors.initials: MC
authors.lastname: Bash
mesh_terms: D000293:Adolescent; D000328:Adult; D000349:Africa; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D001770:Blood Bactericidal Activity; D002648:Child; D002675:Child, Preschool; D003165:Complement System Proteins; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D007074:Immunoglobulin G / Q000097:blood; D022401:Meningococcal Vaccines / Q000008:administration & dosage / Q000276:immunology*; D038381:Neisseria meningitidis, Serogroup A / Q000276:immunology*; D011817:Rabbits; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; C556088:MenACWY-CRM vaccine; C573970:MenAfriVac; D022401:Meningococcal Vaccines; D003165:Complement System Proteins
keywords: MenAfriVac; Neisseria meningitidis; assay development; bactericidal activity; clinical trials