Verapamil and chlorpromazine inhibit the budding of Sindbis and vesicular stomatitis viruses from infected chicken embryo fibroblasts.

Two agents, verapamil and chlorpromazine, which affect calcium levels in cells were tested as inhibitors of Sindbis and vesicular stomatitis virus replication in chicken embryo fibroblasts. At levels which did not greatly inhibit general protein synthesis, both drugs appeared to selectively block virus formation at the final stages of virus assembly and budding. Viral nucleoprotein synthesis and transport of viral glycoproteins to the cell plasma membrane were not inhibited under conditions that blocked virus particle release into the cell culture medium. The effects of the drugs were reversible but no morphologically distinct virus-specific structures were detected in the inhibited cells.