Quantitative tissue invasion of the murine brain as a phenotypic marker of strain virulence in Aspergillus nidulans.

In this study the extent of fungal invasion in tissues of the target organs (brain, heart and kidney) has been quantitated histologically in DBA/2J mice inoculated intravenously with 3 strains of Aspergillus nidulans of different virulence. This was done to determine the relation between tissue invasion and strain virulence as determined by time-mortality bioassay. It was found that quantitatively tissue invasion by A. nidulans was target organ specific. Relative tissue invasion within each of the tissues examined was dependent on the strain of A. nidulans injected. In the brain a direct relationship between strain virulence and the extent of tissue invasion was found. This relationship was not observed in the other 2 target organs. The observations suggest that an important phenotypic marker of murine virulence in A. nidulans is the relative ability to invade the tissues of the murine brain.