Normally, C. albicans cells may reside unobtrusively in tolerable numbers in the mouth, throat, gastrointestinal tract and the vagina. However, disturbances that affect the body's microbial population balance, such as a weakened immune system or use of antibiotics that target a broad range of bacteria, may permit this small population of yeast cells to opportunistically multiply and to expand into the bloodstream and internal organs. The UCSF researchers genetically manipulated C. albicans to create a mutant lacking the TUP1 gene. These mutant yeast cells, they found, always grew into the disease-associated chains. There may be proteins that are part of this regulatory circuitry that could conceivably serve as targets for new anti-fungal drugs.
More serious infections require more intensive treatment.
These include extensive mouth and throat infections that afflict many AIDS patients, and infections that can arise in hospital patients who are connected to intravenous lines or to other catheters used to deliver nutrition. The catheters can serve as a vehicle to convey yeast into the bloodstream and organs. Infection may quickly spread within the body, especially in hospital patients with weakened immune systems or in those receiving broad-spectrum antibiotics. But under the right conditions, TUP1 relaxes its grip and permits downstream gene activation and filament formation, Johnson suggests. Search Copyright 1998 Regents of the University of California.