Interlaboratory Standardization of the Measurement of Serum Bactericidal Activity by Using Human Complement against Meningococcal Serogroup B, Strain 44/76-SL, before and after Vaccination with the Norwegian MenBvac Outer Membrane Vesicle Vaccine

Abstract

There is currently no standardized serum bactericidal antibody (SBA) assay for evaluating immune responses to meningococcal outer membrane vesicle or protein vaccines. Four laboratories, Manchester Health Protection Agency (MC HPA), New Zealand Institute of Environmental Science and Research Limited (NZ ESR), Norwegian Institute of Public Health (NIPH), and Chiron Vaccines (Chiron), measured SBA titers in the same panel of human sera (n ‫؍‬ 76) from laboratory staff (n ‫؍‬ 21) vaccinated with MenBvac. Blood samples were collected prevaccination, prior to each of the three doses of MenBvac given at 6-week intervals, and 6 weeks following the third dose. Initial results showed a number of discrepancies in results between the four participating laboratories. The greatest effect on titers appeared to be due to differences among laboratories in the maintenance of the meningococcal serogroup B test strain, 44/76-SL. A repeat study was conducted using the same frozen isolate (meningococcal serogroup B test strain 44/76-SL), freshly distributed to all four laboratories. Using SBA titers from the tilt method for all samples, and using MC HPA as the comparator, the results were as follows for NZ ESR, NIPH, and Chiron, respectively, using log 10 titers: correlation coefficients (r) were 0.966, 0.967, and 0.936; intercepts were 0.08, 0.15, and 0.17; and slopes were 0.930, 0.851, and 0.891. In both prevaccination and postvaccination samples from 15 subjects assayed by all four laboratories, similar increases in SBA (fourfold or greater) were observed (for 11, 11, 9, and 9 subjects for MC HPA, NZ ESR, NIPH, and Chiron, respectively), and similar percentages of subjects with SBA titers of >4 prevaccination and 6 weeks following each dose were found. The SBA assay has been harmonized between the four different laboratories with good agreement on seroconversion rates, n-fold changes in titers, and percentages of subjects with SBA titers of >4.

Neisseria meningitidis Native Outer Membrane Vesicles Containing Different Lipopolysaccharide Glycoforms as Adjuvants for Meningococcal and Nonmeningococcal Antigens

“…These data demonstrate that nOMVs, containing genetically detoxified LpxL1 LPS, are able to stimulate a functional response against a meningococcal protein antigen, similar to that produced by MPL (26,46). Of greater importance is our demonstration that both nOMVs were superior to aluminum hydroxide.…”

“…H44/76-lgtB was constructed by transforming H44/76 with chromosomal DNA from MC58-lgtB using the spot transformation technique as previously described (26)(27)(28). The transformants were identified on media as described above, supplemented with the appropriate antibiotics, and characterized using PCR and tricine-SDS-PAGE (TSDS-PAGE).…”

Comparison and Correlation of Neisseria meningitidis Serogroup B Immunologic Assay Results and Human Antibody Responses following Three Doses of the Norwegian Meningococcal Outer Membrane Vesicle Vaccine MenBvac

“…Correlations using WBA results were not completed due to sensitivity issues. These results emphasize the need for standardized methodologies such as that recently published for the MenB SBA assay (6). Such standardization would allow more robust comparisons of results between laboratories and promote their further evaluation as correlates of protection against MenB disease.…”

Immunogenicity, Reactogenicity, and Safety of a P1.7b,4 Strain-Specific Serogroup B Meningococcal Vaccine Given to Preteens

“…An interlaboratory study involving laboratories from four countries testing the same sera by serum bactericidal assays showed consistency in the percentages attaining fourfold rises in antibody titer, despite variation in the absolute titers achieved (4,20). Previous studies have correlated the presence of serum bactericidal antibody activity with protection from meningococcal disease (15,16) and have correlated a fourfold rise in serum bactericidal antibody titer postvaccination with vaccine efficacy for serogroup B meningococcal disease in particular (7,21).…”