TABLE 4.
Complement-mediated bactericidal activity of two anti-NspA MAbs
| Strain | Bactericidal activity (μg/ml)a
|
|
|---|---|---|
| AL12 (Ig2a)b | 14C7 (IgG3)b | |
| 1000c | 32 | 4 |
| 8047c | 40 | 2 |
| BZ198c | 30 | 2 |
| S3446c | 80 | 7 |
| BZ232 | >600 | 94 |
| CU385 | >600 | 45 |
| M986 | >600 | 50 |
| MC58 | >600 | 204 |
| NG3/88 | >600 | (120) |
| NGP165 | >600 | (70) |
| BZ198ΔNspA | >600 | >60 |
See Table 3, footnote a.
The MAb 14C7 is a subclass IgG3 MAb and was prone to loss of activity both during purification and as a purified antibody. Therefore, for uniformity, both the 14C7 and the AL12 MAbs used in the assay were precipitated from culture supernatant by ammonium sulfate (50%) and resuspended and dialyzed in PBS buffer containing 1% (wt/vol) BSA. Note that the previously reported concentrations of AL12 for bacteriolysis were slightly lower since purified antibody was used in the experiments. Values in parentheses were static.
Strains selected based on previous data that they were susceptible to complement-mediated anti-NspA bactericidal antibody. The remaining strains were selected based on data showing resistance to anti-NspA bactericidal activity.