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Clinical and Vaccine Immunology, July 2009, p. 969-977, Vol. 16, No. 7
1071-412X/09/$08.00+0 doi:10.1128/CVI.00068-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Investigation of Different Group A Immunoassays following One Dose of Meningococcal Group A Conjugate Vaccine or A/C Polysaccharide Vaccine in Adults
H. Findlow,1*
B. D. Plikaytis,2
A. Aase,3
M. C. Bash,4
H. Chadha,1
C. Elie,2
G. Laher,1
J. Martinez,2
T. Herstad,3
E. Newton,1
S. Viviani,5
C. Papaspyridis,1
P. Kulkarni,6
M. Wilding,1
M. P. Preziosi,7
E. Marchetti,5
M. Hassan-King,5
F. M. La Force,5
G. Carlone,2 and
R. Borrow1
Vaccine Evaluation Unit, Health Protection Agency North West, Manchester Laboratory, Manchester, United Kingdom,1 Centers for Disease Control and Prevention, Atlanta, Georgia,2 Division of Infectious Disease Control, Norwegian Institute of Public Health, NO-0403 Oslo, Norway,3 Center for Biologics Evaluation and Research, FDA, Bethesda, Maryland,4 Meningitis Vaccine Project, PATH, Batiment Avant Centre, 13 Chemin du Levant, 01210 Ferney-Voltaire, France,5 Serum Institute of India Limited, Pune, India,6 Meningitis Vaccine Project, Initiative for Vaccine Research, World Health Organization, Geneva, Switzerland7
Received 13 February 2009/ Returned for modification 31 March 2009/ Accepted 19 May 2009
A double-blind, randomized, controlled phase I study to assess the safety, immunogenicity, and antibody persistence of a new group A conjugate vaccine (PsA-TT) in volunteers aged 18 to 35 years was previously performed. Subjects received one dose of either the PsA-TT conjugate vaccine, meningococcal A/C polysaccharide vaccine (PsA/C), or tetanus toxoid vaccine. The conjugate vaccine was shown to be safe and immunogenic as demonstrated by a standardized group A-specific immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) and by a serum bactericidal antibody (SBA) assay using rabbit complement (rSBA). This report details further analysis of the sera using four additional immunologic assays to investigate the relationship between the different immunoassays. The immunoassays used were an SBA assay that used human complement (hSBA), a group A-specific IgG multiplexed bead assay, and two opsonophagocytic antibody (OPA) assays which used two different methodologies. For each vaccine group, geometric mean concentrations or geometric mean titers were determined for all assays before and 4, 24, and 48 weeks after vaccination. Pearson's correlation coefficients were used to assess the relationship between the six assays using data from all available visits. An excellent correlation was observed between the group A-specific IgG concentrations obtained by ELISA and those obtained by the multiplexed bead assay. hSBA and rSBA titers correlated moderately, although proportions of subjects with putatively protective titers and those demonstrating a 
4-fold rise were similar. The two OPA methods correlated weakly and achieved only a low correlation with the other immunoassays. The correlation between hSBA and group A-specific IgG was higher for the PsA-TT group than for the PsA/C group.
* Corresponding author. Mailing address: Vaccine Evaluation Unit, Health Protection Agency North West, P.O. Box 209, Clinical Sciences Building, Manchester Royal Infirmary, Manchester, United Kingdom. Phone: 44 161 276 6791. Fax: 44 161 276 6792. E-mail: Helen.findlow{at}hpa.org.uk
Published ahead of print on 27 May 2009.
Clinical and Vaccine Immunology, July 2009, p. 969-977, Vol. 16, No. 7
1071-412X/09/$08.00+0 doi:10.1128/CVI.00068-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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