Vaccinia core transcription prevents in vitro depolymerization of polyribosomes in rabbit reticulocyte lysate

When a rabbit reticulocyte lysate is incubated in the presence of vaccinia cores, protein synthesis is impaired at the level of the initiation step and the polyribosomes are depolymerized. However, when the same system is coupled with virus transcription: a) protein synthesis is restored, b) the initiation step is not inhibited, and c) the polyribosomes are not disaggregated. A viral factor activated in the absence of virus transcription and not activated when RNA synthesis occurs may be involved in the early mechanism of protein synthesis inhibition by vaccinia virus.