Hygromycin B is an aminoglycoside antibiotic isolated from Streptomyces hygroscopicus. It is commonly used to study protein synthesis. In addition to being effective against bacteria, fungi, and higher eukaryotic cells, Hygromycin B is also an antiviral that selectively enters cells that have become permeable due to viral infection, thereby inhibiting translation. It is a standard selection antibiotic in genetic experiments, and is particularly useful for selecting for hygromycin-resistant genetically transformed cells.