A Novel in vivo Model of Anaerobic Infection: The Investigation of Clostridium perfringens in Galleria mellonella Larvae.

Important research progress into the mechanisms of Clostridium perfringens associated diseases (CPAD) has been slowed by the lack of a reliable infection model. Wax moth larvae ( Galleria mellonella ) have emerged as a viable alternative to traditional mammalian organisms since they are economic, survive at 37°C and require no specialist equipment. This study aims to establish whether G. mellonella larvae can be developed as a viable model for the study of CPAD and their suitability for studying novel treatment strategies. In addition, the study demonstrates a novel time-lapse approach to data collection. Mortality and morbidity rates of larvae challenged with 10 5 CFU of C. perfringens isolates from various sources were observed over 72h and dose response data obtained using inoculum sizes of 10- 10 5 CFU. Phenoloxidase enzyme activity was investigated as a marker for immune response and tissue burden by histopathological techniques. Results show that C. perfringens is pathogenic towards G. mellonella although potency varies between isolates. Infection activates the melanisation pathway resulting in melanin deposition but no increase in enzyme activity was observed. Efficacy of antibiotic therapy (penicillin G, bacitracin, neomycin and tetracycline) administered parenterally loosely correlates with that of in vitro analysis. The findings suggest G. mellonella can be a useful in vivo model of infection when investigating CPAD. Although they are unlikely to replace traditional mammals they may be useful as a pre-screening assay for virulence of C.perfringens strains or as a simple, cheap and rapid in vivo assay in the development and pre-clinical development of novel therapeutics.