Characterisation and manufacture of a Neisseria gonorrhoeae challenge agent for use in an oropharyngeal controlled human infection model

Oropharyngeal gonorrhoea is a key driver of transmission and antimicrobial resistance (AMR) but remains understudied. To enable translational research, the authors developed a controlled human infection model (CHIM) using Neisseria gonorrhoeae. They characterized five contemporary isolates for antimicrobial susceptibility, in vitro infectivity, cytotoxicity, and serum sensitivity. All isolates infected pharyngeal and cervical cells in vitro, but one was excluded due to an invasive phenotype, elevated inflammatory cytokine production, and high serum resistance. The remaining four isolates were minimally inflammatory, non-cytotoxic, and susceptible to serum killing; three grew in defined liquid medium. Based on these data, a suitable challenge isolate was selected, and a reproducible manufacturing workflow with release testing was established to generate doses for direct oropharyngeal inoculation. The study demonstrates the feasibility of producing a gonococcal challenge agent that aligns with international best practice guidelines, supporting future CHIM-based studies of gonorrhoea pathogenesis, immunity, and therapeutic interventions.