Change in the envelope of a murine retrovirus produced in the presence of toyocamycin]

Toyocamycin (TMC), an adenosine analog, impairs qualitatively and quantitatively virus production in a cellular system chronically infected by Friend Virus. Viral particles released by cell cultures treated with 0.2 microgram/ml of the drug have lost most of their glycoprotein (gp 70) content. This phenomenon is likely to modify the viral envelope and could explain the loss of infectivity of the virus.