TABLE 5.
Human serum bactericidal activity of murine antisera to full-length and mature rNg-ACP protein delivered with different adjuvantsa
| Antigen | Adjuvant | hSBA titer against strain: |
|||
|---|---|---|---|---|---|
| P9-17 WT | P9-17 Δng-acp | FA1090 WT | FA1090 Δng-acp | ||
| Full-length rNg-ACP | Saline | 256 (256, 1024) | 16 | 128 (64, 128) | 4 |
| No antigen | Saline | 64 | 8 (4, 8) | 64 (16, 64) | 4 |
| Mature rNg-ACP | Saline | 256 | 4 (4, 128) | 256 | 64 |
| No antigen | Saline | 4 | <4 | <4 | <4 |
| Full-length rNg-ACP | Al(OH)3 | 512 (256, 512) | 64 | 256 (256, 512) | 64 |
| No antigen | Al(OH)3 | 16 | <4 | <8 | 8 |
| Mature rNg-ACP | Al(OH)3 | 16–64 | 16 (4, 64) | 16 | <4 |
| No antigen | Al(OH)3 | <4 | 8 | 4 | <4 |
| Full-length rNg-ACP | Liposomes | 64 | 16 (16, 64) | 64 | 4 |
| No antigen | Liposomes | 4 (4, 16) | 8 | ≤4 | 4 (4, 8) |
| Mature rNg-ACP | Liposomes | 128–256 | 4 (4, 64) | 64 | <4 (<4, 128) |
| No antigen | Liposomes | 4–8 | 16 | 4 | 4 |
| Full-length rNg-ACP | Liposomes + MPLA | 128 (16, 256) | 32 | 64 (16, 128) | 4 |
| No antigen | Liposomes + MPLA | 16 | 4 | <4 | 4 |
| Mature rNg-ACP | Liposomes + MPLA | 64 | 16 | 64 | <4 |
| No antigen | Liposomes + MPLA | 4 | 4 | <4 | <4 |
| Full-length rNg-ACP | ZW3-14 | 64 | <4 | 64 | ≤4 |
| No antigen | ZW3-14 | <4 | <4 | <4 | 4 |
| Mature rNg-ACP | ZW3-14 | 64 | 4 | 64 | <4 |
| No antigen | ZW3-14 | 4 | <4 | 4 | <4 |
| Full-length rNg-ACP | ZW3-14 + MPLA | 256 (256, 512) | ≤4 | 256 (256, 1024) | 16 |
| No antigen | ZW3-14 + MPLA | <4 | 16 | <8 | 4 |
| Mature rNg-ACP | ZW3-14 + MPLA | 256 (256, 512) | 4 | 256 (256, 512) | <4 |
| No antigen | ZW3-14 + MPLA | 16 | 4 | 16 | 4 |
All mice were administered three 20-µg doses. Pooled antisera raised to full-length and mature rNg-ACP using different adjuvants and the corresponding sham-immunized control sera were tested for their ability to induce complement-mediated killing of N. gonorrhoeae strain P9-17 (homologous allele 10-encoded Ng-ACP) and FA1090 (heterologous allele 6-encoded Ng-ACP) and their corresponding Δng-acp variants. The data presented represent the reciprocals of the highest serum dilution at which ≥50% killing was observed. The titers are expressed as the median values from three or more independent experiments and the range of values in parentheses represent the reciprocal hSBA titers for the number of experiments done. No killing was observed with any of the antisera when tested with normal human serum that had been decomplemented by heat inactivation (titers of <4).