Table 1.
Serogroup A Neisseria meningitidis capsule locus mutants (n = 13) and reference isolates (n = 3) and properties of their capsular polysaccharide.
| Isolate (ST) | Accession Number | Origin | Mutated gene | Base change | Amino acid change | Affected function | Anti-A capsule mAb staining* | Amount of capsule (µg/mL/OD) | O-acetylation (%) | Bactericidal activity of anti-ACWY serum (Mean titre) | Bactericidal activity of anti-LPS mAb (Mean titre) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1976 (7) | ERS041005 | 2004, KND, pharynx | ctrE non-syn. | 1529T->C | L510P | translocation | negative | <1.5 | na | negative | positive (65,020) |
| 2389 (2859) | ERS041030 | 2006, NHD, pharynx | csaD stop | 758G->A | W253X | transport/cross-linking | negative | <1.5 | na | negative | positive (29,440) |
| 1921 (7) | ERS040999 | 2004, KND, pharynx | csaB stop | 915G->A | W305X | polymerase | negative | <1.5 | na | negative | positive (1.2x10^7) |
| 2206 (2859) | ERS041015 | 2006, NHD, pharynx | csaB non-syn | 1157G->A | G386D | polymerase | negative | <1.5 | na | negative | positive (20,914) |
| 2856 (2859) | ERS041053 | 2008, NHD, pharynx | csaB non-syn | 427C->T | P143S | polymerase | normal | 6.7 | not done | positive (9093) |
positive (541,935) |
| 2857 (2859) | ERS041054 | 2008, NHD, pharynx | csaB non-syn | 427C->T | P143S | polymerase | normal | 6.8 | 40 | positive (19,397) |
positive (1.5x10^6) |
| 2717 (2859) | ERS041044 | 2007, NHD, pharynx | csaA non-syn | 941A->C | E314A | epimerase | reduced | 8.5 | 40 | negative | positive (131,164) |
| 2617 (2859) | ERS041041 | 2006, NHD, pharynx | csaA non-syn | 417C->G | S139R | epimerase | normal | 22.7 | 55 | positive (97,813) |
positive (982,603) |
| 1471 (7) | ERS040970 | 2002, KND, pharynx | csaB non-syn | 176C->A | S59Y | polymerase | normal | 41.7 | 60 | positive (3319) | positive (595,269) |
| 2025 (7) | ERS041008 | 2005, KND, pharynx | csaB non-syn | 244A->G | I82V | polymerase | above normal | 71.2 | not done | reduced (49) |
reduced (25) |
| 2008 (7) | ERS041006 | 2005, KND, CSF | csaB non-syn | 244A->G | I82V | polymerase | above normal | 61.4 | 55 | reduced (80) |
reduced (25) |
| 1666 (7) | ERS040979 | 2003, BA, pharynx | csaC stop | 490C->T | Q164X | O-acetyl transferase | negative | 39.7 | no OAc | negative | positive (4.5x10^6) |
| 1573 (7) | ERS040977 | 2003, KND, CSF | ctrD non-syn | 185T->C | I62T | export | normal | 42.2 | 50 | positive (4064) |
positive (412,851) |
| 1446 (7) | ERS040969 | 2002, KND, pharynx | reference isolate | none | none | none | normal | 34.9 | not done | positive (278,672) |
positive (749,690) |
| 2187 (2859) | ERS041012 | 2006, NHD, CSF | reference isolate | none | none | none | normal | 51.8 | 60 | positive (8281) | positive (511,796) |
| 2602 (2859) | ERS041039 | 2007, NHD, CSF | reference isolate | none | none | none | normal | 58.1 | 50 | positive (15,840) |
positive (65,020) |
The amount of capsular polysaccharide was quantified by HPAEC-PAD. Nuclear Magnetic Resonance (NMR) analysis was used to determine the O-acetylation of the cell bound capsule. Abbreviations: non-syn = non-synonymous; na = not analyzable due to lack of polysaccharide; OD = optical density; mAb = monoclonal antibody; Abs = antibodies; CSF = cerebrospinal fluid; KND = Kassena-Nankana District, Ghana; BA = Bolgatanga district, Ghana; NHD = Nouna Health District, Burkina Faso.
*Flow cytometry was used to determine the capsule expression of the mutant isolates relative to the reference isolates.