Synthesis of frog virus 3 proteins occurs on intermediate filament-bound polyribosomes

Immunogold labeling and biochemical methods were used to localize the site of viral protein synthesis in frog virus 3 (FV3)-infected baby hamster kidney (BHK) cells. Immunogold labeling studies of Triton-extracted (cytoskeletons), FV3-infected BHK cells with antivimentin antibodies showed that the major components of the detergent-resistant residue are the intermediate filaments (IF) and polyribosomes. Double immunogold labeling studies with anti-FV3 and antivimentin antibodies revealed that FV3 proteins are associated with polyribosomes that are bound to the IF network. Biochemical studies of the cytoskeletons prepared from FV3-infected cells showed that a substantial fraction of all newly synthesized FV3 proteins associate with the cytoskeleton and that the association is not disrupted by colchicine (microtubule-disrupting drug) or cytochalasin B (microfilament-disrupting drug). Together the above studies suggest that IF may provide the scaffold for the attachment of polyribosomes that are active in viral protein synthesis.