The HO (Hmx1) of the pathogenic yeast Candida albicans and its product, CO, also contribute to pathogenesis (64); mutagenesis of the HMX1 gene results in decreased virulence in murine candidiasis, whereas exposure of mice to therapeutic levels of CO increases C. albicans virulence. The gene discussed is HMX1; the disease is Candidiasis, Invasive.