TABLE 1.
Strains used in the PMN phagocytosis assay and a summary of results
| Strain | Description of strain | In vitro sensitivitya
|
PMN sensitivityc | |
|---|---|---|---|---|
| Sensitivity (substance) | Reference | |||
| N. gonorrhoeae 1291 | Wild type | − | ||
| sodB | Sod deficient | X (PQ, X/XO) | 49 | − |
| mntC | Lacks periplasmic Mn-binding protein of MntABC transporter (decreased [Mn] in cells) | S (PQ) | 49 | − |
| katA | Catalase deficient | S (H2O2) | 42 | − |
| ccp | Cytochrome c peroxidase deficient | S (H2O2 [slight]) | 42 | − |
| ccp katA | Ccp and catalase double mutant | S (H2O2) | 42 | − |
| sco | Sco deficient (potential thiol-disulfide oxidoreductase) | S (PQ) | 41 | − |
| sco katA | Sco and catalase double mutant | S (PQ, H2O2) | 41 | − |
| oxyR | Overexpresses KatA | R (X/XO, H2O2) | 48 | − |
| perR | Overexpresses MntC (increased [Mn] in cells) | R (H2O2) | —b | − |
| E. coli DH5α | Wild type | + | ||
The strains used in the PMN phagocytosis assay are shown along with a summary of the results from this assay and results from in vitro assays from previous publications. Sensitivities of mutant strains to in vitro oxidative stress killing assays are shown relative to N. gonorrhoeae strain 1291 (wild type): X, same phenotype as wild type; S, sensitive to killing; R, resistant to killing (increased survival relative to wild type). These assays involved exposure of a suspension of 104 to 106 cells to either paraquat (PQ; 10 mM), xanthine (4.3 mM)/xanthine oxidase (300 mU/ml) (X/XO), or hydrogen peroxide (H2O2; 10 or 40 mM). For further details, see the references cited in the table.
—, H.-J. Wu, K. L Seib, Y. N. Srikhanta, J. L. Edwards, S. P. Kidd, M. A. Apicella, A. G. McEwan, and M. P. Jennings, submitted for publication.
PMN sensitivity (+) is defined as a statistically significant difference in the mean percent survival of the strain relative to N. gonorrhoeae strain 1291 (wild type) in the PMN phagocytosis assay. P values that are <0.05 are considered statistically significant. Differences between N. gonorrhoeae 1291 and its mutant derivatives were not statistically significant (−) (Fig. 1) (P values ≥ 0.14).