Galleria mellonella – a novel infection model for the study of Neisseria gonorrhoeae virulence and pathogenicity

Gonorrhea is the second most commonly reported notifiable sexually transmitted disease in the world. Neisseria gonorrhoeae causes 78 million cases annually of gonorrhoea worldwide. There are no vaccines and antibiotic-resistant organisms are circulating rapidly. The estradiol-treated female mouse model is the only animal model available for studying the host response against gonococci and biological significance of host-restricted bacterial-host cell interactions observed in vitro . However, mouse models have limitations such as cost, time and ethics. Therefore, there is an urgent need for the development of new alternative in vivo models. The Galleria mellonella larval model is a simple, widely available, cost-effective, and powerful tool for studying microbial infections prior to any vertebrate animal testing. Here we report, for the first time, that G. mellonella can be used as an infection model for Neisseria spp., focusing particularly on N. gonorrhoeae . We demonstrated dose-dependent larval death and recovery of viable gonococci from the host, visualised host-pathogen interactions using histopathology and confirmed the importance of insect haemocytes as an innate immune cell during infection. The model was also used to test the efficacy of antibiotics used to treat gonorrhoea. Our results demonstrate that G. mellonella can be used as a model to study pathogenesis and virulence of gonococcal infection in addition to rapid in vivo testing of antimicrobials.