FLI-Seminar with Thilo M. Fuchs: Galleria mellonella larvae – a surrogate model in infection biology

Jena. Larvae of Galleria mellonella, commonly known as the Greater wax moth, have become a valuable model for studying host-pathogen interactions. The talk will emphasize the larvae’s versatility and relevance as an alternative in vivo model for assessing microbial virulence, testing antimicrobial agents, and understanding the innate immune response. The larvae's easy maintenance, cost-effectiveness, and ethical considerations make them an attractive surrogate for higher vertebrates in infection studies.

The human pathogen Yersinia enterocolitica strain W22703 exhibits insecticidal and nematocidal activity. This phenotype is caused by proteins of the toxin complex (Tc) encoded on the pathogenicity island Tc-PAIYe. Using G. mellonella larvae, the research group led by Prof. Thilo M. Fuchs established an oral model of infection that allowed following the natural route of infection. For this purpose, larvae were infected with strain W22703 and its tc-gene mutants, and the survival rate of the insect were determined in correlation with Y. enterocolitica cell numbers. Time course experiments allowed the dissection of distinct Y. enterocolitica infection stages starting with gut colonisation followed by invasion of the hemolymph, where the pathogen strongly proliferates (Sänger et al. 2022 PLoS Pathogens 18:e1010991). The in vivo transcriptome of strain W22703 is mainly characterized by a drastic reprogramming of the energy, amino acid and carbohydrate metabolism, by an increase of motility and signaling molecules, and by cell membrane rearrangements. Several phenotypes including penetration of the gut epithelium depend on the presence of the Tc proteins. Strikingly, a mutant lacking a holin/endolysin cassette, which is located within Tc-PAIYe, resembled the phenotypes of W22703 ΔtcaA. Thilo M. Fuchs sees this as demonstration of the central role of Tc proteins in the infection and killing of insect larvae, to which Y. enterocolitica adapts through a specific transcription program. In his opinion, a holin/endolysin pair is essential for insecticidal activity and constitutes an example of the novel type ten secretion system (T10SS) for toxin release by bacteria.

Information about Prof. Dr. Thilo M. Fuchs:
- Institute of Molecular Pathogenesis (IMP) at Friedrich-Loeffler-Institut – Federal Research Institute for Animal Health

- Working group Pathobiology of Mycobacterioses

The seminar will take place in person.