Table 1.

Reactivity of anti-rNspA polyclonal antiserum with NspA exposed on the surface of live, encapsulated, N. meningitidis serogroup B bacteria in relation to susceptibility to bacteriolysis and capsule production

N. meningitidis serogroup BaNspA cell surface reactivitydAnti-rNspA bactericidal activitye (reciprocal titer)Polysaccharide capsule production (reciprocal/titer)f
StrainCountryYrSerologic classificationcET complex
SWZ107b Switzerland19804:P1.2104Positive≥64 28 ± 4
NG6/88b Norway1988NT: P1.1173Positive4 115 ± 23
CU385Cuba19804: P1.155Positive4 116 ± 1
IH5341Finland198515:P1.7,16NDPositive16 176 ± 61
BZ198The Netherlands1986NT: P−154Positive≥64 362 ± 1
NMBUnited States19682b:P1.2,5NDPositive16 244 ± 20
8047United States19782b: P1.2NDPositive16 1,125 ± 50
H44/76Norway197615: P1.7, 165Positive24 99 ± 16
1000b USSR1989NT:P1.561Positive<4 287 ± 12
S3446United States197214: P1.23, 1411 (A1 cluster)Positive<4 (static=16)585 ± 151
H355Norway197315: P1.1511 clusterPositive<4 (static=4)656 ± 141
BZ232b The Netherlands1964NT:P1.276Negative<4 1,493 ± 18
NG3/88b Norway19888: P1.1A4 clusterNegative<4 498 ± 105
MC58United Kingdom198515:P1.7,16b5Negative<4 627 ± 121
M136United States196811: P1.15D1 clusterNegative<4 1,056 ± 81
M986United States19632a: P1.5, 2B2 clusterNegative<4 1,442 ± 206
NGP165Norway1974NT:P1.237Negative<4 138 ± 6
  • a Strains were obtained from the collection of C. Frasch, Center for Biologics Evaluation and Research, Rockville, Md.; 8047 was obtained from W. Zollinger, Walter Reed Army Institute of Research, Washington, D.C.; MC58 is the strain selected by The Institute of Genomic Research for genomic sequencing; IH5341 was obtained from M. Sarvas, National Public Health Institute, Helsinki, Finland; and the remaining strains are from the collection described by Seiler et al. (57). ET data are from Caugnant et al. (9) and Seiler et al. (57).

  • b Strain has been characterized further by multilocus sequence typing (33).

  • c See reference 19 for a definition of the meningococcal serotype and subtype classification system.

  • d By indirect-fluorescence flow cytometry with anti-rNspA antisera.

  • e Dilution of anti-rNspA antisera that when incubated for 60 min with bacterial cells and 20% human complement yielded a 50% decrease in CFU per milliliter compared to that at time zero. “Static” refers to strains that were inhibited but not killed in the assay (≥50% but <100% survival at 60 min.).

  • f Titer defined as dilution of capsule extract giving 50% inhibition of antibody binding to meningococcal B polysaccharide antigen in an ELISA (see Materials and Methods). Results are means and standard errors.