Development of an Innovative Galleria mellonella Model for Ricin Poisoning

Ricin is considered a chemical and biological weapon. It is found in the seeds of a plant, Ricinus communis. There are different isoforms of ricin with different levels of toxicity, depending on the R. communis plant. There is no current prophylaxis and specific treatment for ricin poisoning is recent. Assessing potential countermeasures against this toxin still relies on testing on vertebrate animal models. Galleria mellonella larva, already used for the testing of bacteria, viruses, and fungi, represents an alternative model that is more ethical, inexpensive, and easier to use. In this study, we demonstrated for the first time the sensitivity of G. mellonella larvae to different cultivars of ricin. We observed mortality and a reduction in health index scoring over the days of testing. The health index scoring was based on the survival, the melanization, the mobility, and the capacity of larvae to produce a cocoon or not. Mortality was cultivar- and dose-dependent. Mortality of G. mellonella larvae was reduced when they were treated with a monoclonal antibody and concomitantly injected with ricin. Thus, G. mellonella represents a rapid and simple model of ricin poisoning, and, more particularly, a relevant model to test new therapeutics against ricin.