The A. fumigatus genome is 28 Mb in size, consisting of 8 chromosomes bearing a total of almost 10,000 genes. Which genes make the mold virulent? Some 700 A. fumigatus genes significantly differ--or do not even occur--in a similar, yet less infectious fungus, Neosartorya fischeri. Nierman and colleagues are now searching these unique genes for clues to A. fumigatus infectivity.
It's a complex task. Suspect genes encode proteins involved in central metabolic pathways, cell signaling, cell wall biosynthesis, pigment biosynthesis, and secondary metabolite production. In other words, A. fumigatus's virulence genes are likely complex and mixed up with normal metabolic capabilities, Nierman says. He and his colleagues now plan to systematically 'knock out,' or disable, genes that might make A. fumigatus infectious. Eventually, Nierman adds, this work could lead to better therapies for serious asthma, allergy, and other conditions."