COS-I, a putative two-component histidine kinase of Candida albicans, is an in vivo virulence factor

The human fungal pathogen, Candida albicans, has three putative histidine k inases showing homology to those of plants, bacteria and other fungi. We ha ve constructed a homozygous deletion strain and a hemizygous reconstituted strain of one of these histidine-kinase-encoding genes, COS-1, in C. albica ns. Neither strain showed any growth defect in a number of liquid media nor increased resistance or sensitivity to a number of antifungal drugs, Impor tantly, we show that the COS-1 homozygous disruption strain had significant ly reduced virulence in a systemic murine model of candidosis. Thus, COS-1 appears to be an in vivo virulence factor and may represent a novel target for the development of antifungal drugs.