Loss and regain of virulence of a Candida albicans mutant as assessed in systemic murine candidiasis

Aim. The virulence ability of Candida albicans strain CBS562, its histidine auxotroph mutant (SAG5) and a respiratory-deficient mutant of the his^-strain (SAR1) was tested in a murine model of systemic candidiasis. Results. The results demonstrated that both mutant strains were significantly less virulent in this animal model as compared to the wild type. This was demonstrated by decreased percentage of mortality, increased survival time and lower fungal load in target organs. To verify whether the prototrophy will restore the virulence ability, we tested the virulence ability of the histidine auxotroph transformant in comparison to that of the wild type, the his^- mutant (SAG5) and the plasmid-cured transformant. The virulence of the his^-transformant was similar to that of the wild type, whereas the virulence ability of the plasmid-cured strain was similar to that of SAG5. Conclusion. In summary, this study demonstrated loss of virulence in C. albicans mutants and regain of the virulence by transformation from auxotrophy to prototrophy.