Seminal Plasma Promotes Neisseria gonorrhoeae Aggregation and Biofilm Formation

Abstract

Neisseria gonorrhoeae causes the human-specific disease gonorrhea and is transmitted from person to person primarily via sexual contact. During transmission, N. gonorrhoeae is often exposed to seminal fluid and must adapt to this change in environment. Previous work demonstrated that seminal fluid facilitates N. gonorrhoeae motility and alters epithelial cell interactions. In this study, exposure to seminal fluid was found to decrease surface adherence of gonococci in a manner that was independent of Opa adhesin proteins or type IV pilus retraction. Semen was also shown to cause dispersal of bacteria that had previously established surface adherence. Although surface adherence decreased, interbacterial interactions were increased by seminal plasma both in long-term static culture and on a cell-to-cell basis over shorter time periods. The result of increased bacterium-bacterium interactions resulted in the formation of microcolonies, an important step in the N. gonorrhoeae infectious process. Seminal fluid also facilitated increased bacterial aggregation in the form of shear-resistant three-dimensional biofilms. These results emphasize the importance of the gonococcal response to the influx of seminal fluid within the genital niche. Further characterization of the N. gonorrhoeae response to semen will advance our understanding of the mechanisms behind the establishment of infection in naive hosts and the process of transmission. IMPORTANCE N. gonorrhoeae is the causative agent of the globally prevalent sexually transmitted infection gonorrhea. An understudied aspect of this human-adapted pathogen is the change in bacterial physiology that occurs during sexual transmission. N. gonorrhoeae encounters semen when transmitted from host to host, and it is known that, when N. gonorrhoeae is exposed to seminal fluid, alterations in bacterial motility and type IV pilus arrangement occur. This work extends our previous observations on this modulation of gonococcal physiology by seminal fluid and demonstrates that seminal plasma decreases surface adherence, promotes interbacterial interactions, and enhances biofilm formation.

Lipid-Modified Azurin of Neisseria gonorrhoeae Is Not Surface Exposed and Does Not Interact With the Nitrite Reductase AniA

“…This assay did not reveal any difference in biofilm mass produced by the Δ laz mutant compared to WT bacteria (Figure 5K ). Our findings are consistent with the involvement of AniA and Ccp in early stages of biofilm formation reported by others ( Falsetta et al, 2009 ), and suggest that Laz and the two other electron transport proteins are dispensable during early stages of gonococcal biofilm formation ( Anderson et al, 2016 ).…”

“…The ability of WT and Δ laz bacteria to form biofilms was examined as described ( Anderson et al, 2016 ), with the exception that bacterial suspensions were prepared in GCBL. A BioTek Synergy HT plate reader (BioTek) was used to measure biofilm mass at 550 nm.…”

Discovery of a newNeisseria gonorrhoeaeType IV pilus assembly factor, TfpC

“…Positive pools were repeated by PCR using individual clones as templates and then the promoter was amplified and sequenced with USS2 (43) and pilAREV, the pilE locus was amplified and sequenced with PilRBS and SP3A (39). This strain was the recipient in a transformation reaction with an approximately 950 bp gBlock (synthesized by Integrated DNA Technologies) carrying a DUS12 sequence and pilC1 PL allele (44,45) that maintains the pilC1 gene in a phase "on" conformation, which was flanked by 471 bp and 463 bp of homology on the 5' and 3' of DUS12-pilC1 PL , respectively, to the pilC1 locus. Dilutions of the transformation was grown on GCB plates and grown for 63.5 hours at 37 C in the presence of 5% CO 2 .…”

“…The pilus is an essential factor for colonization, enhancing the ability of the bacterium to adhere to and interact with host cells and tissues at infection sites (10). The pilus is also required to promote bacteria-bacteria interactions, the formation, and dissolution, of microcolonies and biofilms (11). The T4p is required for twitching motility, a specialized form of locomotion that requires T4p retraction (9), to enhance bacterial interactions with the epithelium (12).…”

Discovery of a New Neisseria gonorrhoeae Type IV Pilus Assembly Factor, TfpC

“…The pilus is an essential factor for colonization, enhancing the ability of the bacterium to adhere to and interact with host cells and tissues at infection sites ( 10 ). The pilus is also required to promote bacterium-bacterium interactions and the formation and dissolution of microcolonies and biofilms ( 11 ). T4p are required for twitching motility, a specialized form of locomotion that requires T4p retraction ( 9 ), to enhance bacterial interactions with the epithelium ( 12 ).…”