The Gonococcal Transcriptome during Infection of the Lower Genital Tract in Women

Abstract

Gonorrhea is a highly prevalent disease resulting in significant morbidity worldwide, with an estimated 106 cases reported annually. Neisseria gonorrhoeae, the causative agent of gonorrhea, colonizes and infects the human genital tract and often evades host immune mechanisms until successful antibiotic treatment is used. The alarming increase in antibiotic-resistant strains of N. gonorrhoeae, the often asymptomatic nature of this disease in women and the lack of a vaccine directed at crucial virulence determinants have prompted us to perform transcriptome analysis to understand gonococcal gene expression patterns during natural infection. We sequenced RNA extracted from cervico-vaginal lavage samples collected from women recently exposed to infected male partners and determined the complete N. gonorrhoeae transcriptome during infection of the lower genital tract in women. On average, 3.19% of total RNA isolated from female samples aligned to the N. gonorrhoeae NCCP11945 genome and 1750 gonococcal ORFs (65% of all protein-coding genes) were transcribed. High expression in vivo was observed in genes encoding antimicrobial efflux pumps, iron response, phage production, pilin structure, outer membrane structures and hypothetical proteins. A parallel analysis was performed using the same strains grown in vitro in a chemically defined media (CDM). A total of 140 genes were increased in expression during natural infection compared to growth in CDM, and 165 genes were decreased in expression. Large differences were found in gene expression profiles under each condition, particularly with genes involved in DNA and RNA processing, iron, transposase, pilin and lipoproteins. We specifically interrogated genes encoding DNA binding regulators and iron-scavenging proteins, and identified increased expression of several iron-regulated genes, including tbpAB and fbpAB, during infection in women as compared to growth in vitro, suggesting that during infection of the genital tract in women, the gonococcus is exposed to an iron deplete environment. Collectively, we demonstrate that a large portion of the gonococcal genome is expressed and regulated during mucosal infection including genes involved in regulatory functions and iron scavenging.

Characterization of the Neisseria gonorrhoeae Iron and Fur Regulatory Network

“…The importance of these proteins is shown by the avirulent nature of a tbp-deficient strain of N. gonorrhoeae in experimental infection of the male genital tract in humans (24). In addition, we have reported that fur, tbpB, and fbp are expressed during natural gonococcal infection, supporting a role for Fur-mediated control of gene expression during the pathogenic process (2,3,25).…”

Haemophilus ducreyi Seeks Alternative Carbon Sources and Adapts to Nutrient Stress and Anaerobiosis during Experimental Infection of Human Volunteers

“…None of these comparisons achieved statistical significance by chisquare analysis. The lack of overlap may be because these regulons were determined by comparing differential gene expression in strains where the regulator was either present or induced to that of a strain where the regulator was either absent (54)(55)(56)(57)(58)(59)(60). Several of these studies reported the upregulation of genes involved in the transport of transition metals, peptides, and amino acids during human infection.…”

Against the tide: the role of bacterial adhesion in host colonization

“…Other species known to respond to surface adherence by triggering transcriptional changes include Neisseria meningitidis , Caulobacter crescentus , and Trichomonas vaginalis . Interestingly, not all of these changes are directly implicated in bacterial pathogenicity — often they affect global functions underpinning bacterial physiology, including DNA and RNA processing, genome stability, and bacterial metabolism [27–30]. In conclusion, if a bacterium adheres to a surface, no matter if this is a short-lived or prolonged interaction, this can be termed colonization.…”