Development of an insect model for the in vivo pathogenicity testing of yeasts

Conventional in vivo assays to determine the relative pathogenicity of yeas t isolates rely upon the use of a range of mammalian species. The purpose o f the work presented here was to investigate the possibility of using an in sect (Galleria mellonella) as a model system for in vivo pathogenicity test ing. The haemolymph of G. mellonella larvae was inoculated with PBS contain ing different concentrations of stationary phase yeasts of the genus Candid a by injection at the last pro-leg. Larvae were incubated at 30 degrees C a nd monitored over 72 hours. Results indicate that G. mellonella can be kill ed by the pathogenic yeast Candida albicans and by a range of other Candida species but not to a significant extent by the yeast Saccharomyces cerevis iae. The kill kinetics for larvae inoculated with clinical and laboratory i solates of C. albicans indicate the former class of isolates to be more pat hogenic. Differences in the relative pathogenicity of a range of Candida sp ecies may be distinguished using G. mellonella as a model. This work indica tes that G. mellonella may be employed to give results consistent with data previously obtained using mammals in conventional in vivo pathogenicity te sting. Larvae of G. mellonella are inexpensive to culture. easy to manipula te and their use may reduce the need to employ mammals for routine in vivo pathogenicity testing with a concomitant reduction in mammalian suffering. (C) 2000 Federation of European Microbiological Societies. Published by Els evier Science B.V. All rights reserved.