Moth larvae instead of mice

To understand the molecular basis of inflammatory bowel diseases in humans, experiments are carried out with mice that have been given genetically modified (gm) Enterobacteria The functions of individual bacterial cells can then be determined on the treated animals using physiological or histological parameters. Pathogenicity factors These infection experiments generally involve genetic engineering work at safety level 2, which, in accordance with the Genetic Engineering Safety Ordinance (GenTSV), is associated with specific organizational and technical safety measures in the respective animal facilities and laboratories. These include, among other things, housing the infected animals in cages or enclosures with suitable exhaust air filtration, or thermal treatment of the carcasses of infected animals in an autoclave according to a previously validated inactivation program.

A complement or alternative to the described experiments in mice is a model system with the larvae of the Greater wax moth (Galleria mellonella). Existing similarities in the immune response and pathogenesis of inflammatory bowel diseases between the larvae and mice (or humans) are exploited. The larvae are "fed" with the corresponding bacteria for the experiments and then colonize the digestive system of the animals. Depending on the injected GM bacterium, this leads to pathological symptoms within a few hours or days, including the death of the larvae. Using molecular biological or immunohistological analyses, the course of inflammation can be followed in detail and thus specific mechanisms of action (e.g. bacterial toxins ). In the experiments, the larvae themselves are not genetically modified, but are only considered carriers of the GM bacteria.

The wax moth larvae model system offers further advantages in addition to reducing time-consuming and costly mouse studies. For example, infection experiments usually require an S2 laboratory, but no additional Animal husbandry required as long as the experimental protocol ensures that no flight-capable moths develop from the larvae. Furthermore, very small quantities of GM bacteria can be used for the applications. After the experiments, infected larvae can be inactivated in an autoclave following a standard protocol for the thermal treatment of (solid) waste.

Before using the wax moth larvae model system for genetic engineering work, it should be clarified with the responsible regulatory authority whether and how this method must be reported as further S2 work and which safety measures (e.g. during the application of the GM bacteria) are considered necessary.