Researchers developed a new way to fight dangerous fungal infections caused by Aspergillus fumigatus, which increasingly resists standard antifungal drugs. They used tiny molecules called microRNAs packaged in even tinier delivery vehicles to turn off genes that help the fungus survive. When these microRNAs were introduced, the fungus became much more vulnerable to the body’s immune system and to stress. This novel approach could eventually help treat infections that are otherwise difficult to cure.