title: Serum antibody responses in Ethiopian meningitis patients infected with Neisseria meningitidis serogroup A sequence type 7.
abstract: To elucidate critical components of protective immune responses induced during the natural course of serogroup A meningococcal disease, we studied acute-, early-convalescent-, and late-convalescent-phase sera from Ethiopian patients during outbreaks in 2002 to 2003. Sera were obtained from laboratory-confirmed patients positive for serogroup A sequence type 7 (ST-7) meningococci (A:4/21:P1.20,9) (n = 71) and from Ethiopian controls (n = 113). The sera were analyzed using an enzyme-linked immunosorbent assay to measure levels of immunoglobulin G (IgG) against serogroup A polysaccharide (APS) and outer membrane vesicles (OMVs) and for serum bactericidal activity (SBA) using both rabbit and human complement sources. Despite relatively high SBA titers and high levels of IgG against APS and OMVs in acute-phase patient sera, significant increases were seen in the early convalescent phase. Antibody concentrations returned to acute-phase levels in the late convalescent phase. Considering all patients' sera, a significant but low correlation (r = 0.46) was observed between SBA with rabbit complement (rSBA) using an ST-5 reference strain and SBA with human complement (hSBA) using an ST-7 strain from Ethiopia. While rSBA demonstrated a significant linear relation with IgG against APS, hSBA demonstrated significant linear relationships with IgG against both APS and OMV. This study indicates that antibodies against both outer membrane proteins and APS may be important in providing the protection induced during disease, as measured by hSBA. Therefore, outer membrane proteins could also have a role as components of future meningococcal vaccines for the African meningitis belt.
authors.affiliation: Division of Infectious Disease Control, Norwegian Institute of Public Health (NIPH), Oslo, Norway.
authors.forename: Gunnstein
authors.initials: G
authors.lastname: Norheim
authors.forename: Abraham
authors.initials: A
authors.lastname: Aseffa
authors.forename: Mohammed Ahmed
authors.initials: MA
authors.lastname: Yassin
authors.forename: Getahun
authors.initials: G
authors.lastname: Mengistu
authors.forename: Afework
authors.initials: A
authors.lastname: Kassu
authors.forename: Dereje
authors.initials: D
authors.lastname: Fikremariam
authors.forename: Wegene
authors.initials: W
authors.lastname: Tamire
authors.forename: Yared
authors.initials: Y
authors.lastname: Merid
authors.forename: E Arne
authors.initials: EA
authors.lastname: Høiby
authors.forename: Dominique A
authors.initials: DA
authors.lastname: Caugant
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Fritzsønn
authors.forename: Torill
authors.initials: T
authors.lastname: Tangen
authors.forename: Tsegaye
authors.initials: T
authors.lastname: Alebel
authors.forename: Degu
authors.initials: D
authors.lastname: Berhanu
authors.forename: Morten
authors.initials: M
authors.lastname: Harboe
authors.forename: Einar
authors.initials: E
authors.lastname: Rosenqvist
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000907:Antibodies, Bacterial / Q000096:biosynthesis / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005002:Ethiopia / Q000453:epidemiology; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008585:Meningitis, Meningococcal / Q000453:epidemiology / Q000276:immunology*; D008875:Middle Aged; D038381:Neisseria meningitidis, Serogroup A / Q000235:genetics / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial