Two different mechanisms of the inhibition of the multiplication of enveloped viruses by glucosamine.

In Earle's medium containing 10 mM glucose, glucosamine inhibits the multiplication of fowl plague virus (FPV) and Semliki Forest virus (SFV) by interfering with the synthesis of viral glycoproteins, while the synthesis of viral RNA and carbohydrate-free proteins is affected only slightly or not at all. If glucose is replaced by fructose, glucosamine inhibits the synthesis of viral RNA and in this way interferes with the production of all viral proteins. Protein and RNA synthesis of non-infected cells are not significantly impaired under these conditions. The effect on viral RNA synthesis can be readily counteracted by uridine. The inhibition of viral glycoprotein synthesis cannot be reversed at all by uridine and that of viral carbohydrate-free proteins only to a very limited extent. In fructose-containing medium, glucosamine depletes the cells of UTP in such a way that the UTP pool may become rate limiting for viral RNA synthesis but not for cellular RNA synthesis.The multiplication of Newcastle disease virus (NDV) and vesicular stomatitis virus (VSV) is inhibited by glucosamine only in fructose-containing medium but not in glucose-containing medium.