Inhibition of alfalfa mosaic virus RNA and protein synthesis by actinomycin D and cycloheximide.

Actinomycin D, added early after inoculation, reduces the production of infectious alfalfa mosaic virus in cowpea protoplasts by 90%. This reduction was associated with an inhibition of viral minus-strand and plus-strand RNA synthesis, suggesting the involvement of host factors in these processes. Coat protein production was less affected by the drug. Addition of cycloheximide throughout the growth cycle resulted in an immediate cessation of coat protein production and an enhanced degradation of viral RNA. This degradation obscured possible effects of the drug on viral RNA synthesis.