FIG 5.

Neutrophil challenge selects for phase-OFF expression of Opa proteins that drive association of N. gonorrhoeae with neutrophils, increasing overall survival of the population of N. gonorrhoeae. N. gonorrhoeae bacteria that were constitutively expressing (nv) or phase-ON (⁺) for OpaI (A) or OpaD (D) were exposed to adherent, IL-8-treated primary human neutrophils, and CFU were enumerated from bacterial lysates over time as for Fig. 3. Bacterial survival is expressed relative to the CFU enumerated at time zero. At each time point from panels A and D, opacity phenotype of the enumerated CFU was visually inspected and recorded. Results are reported as the percentage of colonies at the indicated time point that retained Opa expression (dark bars) or were Opa negative (light bars). No other opacity phenotypes other than the indicated OpaI⁺ (B) and OpaD⁺ (E) were observed. The same starting cultures of OpaI⁺ (B) and OpaD⁺ (E) as above were inoculated into media without neutrophils, and CFU of Opa⁻ and Opa⁺ phenotypes were enumerated and plotted. No change was seen for with OpaI⁺ (C) or OpaD⁺ (F). ΔopaBEGK (G), OpaA⁺ (H), and OpaF⁺ (I) N. gonorrhoeae strains were exposed to neutrophils, and the opacity phenotypes of the CFU recovered at each time point were plotted as in panels B and E. Statistical comparisons were by two-way ANOVA with post hoc Tukey multiple-comparison test, with the following pairwise significances: *, P < 0.05, **, P < 0.01, ****, P < 0.0001.