Cryptococcal infections are a global cause of significant morbidity and mortality. We have shown that C. neoformans kills the nematode C. elegans and that several C. neoformans genes previously shown to be involved in mammalian virulence also play a role in C. elegans killing (PNAS 99:15675, 2002). We are using the C. neoformans/C. elegans model to identify novel genes that are associated with evolutionarily conserved aspects of cryptococcal virulence. Methods: We used the C. elegans/C. neoformans model to screen a bank of random insertional mutants that were developed in the C. neoformans H99 background. DNA flanking insertions in mutants with attenuated virulence was obtained by inverse PCR. Mutants are crossed to a pathogenic wild type strain to confirm linkage between the insertions and attenuated virulence phenotypes. Results: Among 300 mutants of C. neoformans that we have screened so far, we found that 15 (5%) of these mutants were attenuated in the initial C. elegans screen and that nine of these mutants (3%) were confirmed as attenuated on repeated evaluation. At this point, we have identified the genes mutated in five of these mutants. Several of these genes have likely roles in mammalian pathogenesis and are being analyzed further. Genetic analysis of the mutations is also underway. Conclusions: We have shown that C. elegans can be used as a facile model host in which to model C. neoformans pathogenesis and that this model system can be used to rapidly screen for new genes important in virulence. Ultimately, this may lead to new targets for antifungal therapies.
Full conference title:
41st Annual Meeting Infectious Diseases Society of America
- Infectious Diseases Society of America 41st