Abstract
Aspergillus fumigatus is an opportunistic fungal pathogen that has recently been found to undergo sexual reproduction. Previous work suggested that invasiveness differs between mating types, and in the present study we tested whether virulence differs between mating types in an in vivo model, i.e., larvae of the wax moth Galleria mellonella. We measured virulence of 20 A. fumigatus isolates; three MAT1-1 isolates of environmental origin, five MAT1-1 isolates of clinical origin, seven MAT1-2 isolates of environmental origin and five MAT1-2 isolates of clinical origin. For each isolate, we measured virulence in six replicates and for each replicate, conidia were grown, harvested, and counted independently, and 2,500 colony forming units were injected into each of 10 G. mellonella larvae. Virulence differed between mating types, with lower survival in larvae injected with MAT1-1 isolates. Virulence also differed between clinical and environmental isolates, but surprisingly larvae injected with environmental isolates had lower survival. Identification of the mechanisms underlying variation in virulence may identify novel targets for the treatment of Aspergillus infections.
Acknowledgements
We thank Saira Chaudhry, Balveer Mandar, and Joshua Ogden for technical help, Pilar Cepada for guidance in rearing G. mellonella, Fabrice Gravelat for advice regarding the use of G. mellonella as a model, Linda Pinto and Margo Moore for providing advice and some of the isolates used in this study, and Darby Thompson, Charmaine Dean and Karl Clemons for advice regarding statistical analysis and constructive comments on the manuscript. This study was funded by a Natural Sciences and Engineering Research Council (NSERC) operating grant (326791-06) and a Simon Fraser University President's Research Grant to JKC.
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this paper.
This paper was first published online on Early Online on 7 September 2010.