ECE1 and infection: Notably, several of the most strongly downregulated genes under anaerobic conditions are known virulence factors: ECE1 (candidalysin, a cytolytic peptide toxin essential for mucosal invasion), PLB1 (a lysophospholipase used by C. albicans to damage and traverse host cell membranes), CDC5 (a polo-like serine/threonine kinase involved in filamentation and virulence), and SAP7 (a secreted aspartyl protease highly expressed during infection; Fig. 4C).