Safety of viral vaccine cell substrates: a reevaluation

Primary cultures of African green monkey kidney and rabbit kidney as well as diploid cell lines WI-38 and DBS-FRhL-2 were examined for evidence of tumorigenicity and latent RNA tumor viruses. Cells inoculated into immunosuppressed newborn hamsters and rhesus monkeys were not tumorigenic. Cells treated with 2'-deoxy-5-iodouridine to induce the production of latent viruses were examined by electron microscopy, density gradient centrifugation, and the reverse transcriptase enzyme assay. No evidence was found for RNA tumor viruses by the biochemical or biophysical methods used. The results indicated that each type of mammalian cell currently used in the production of virus vaccines would be acceptable for these parameters of safety if similar control procedures were applied at the time the vaccines were manufactured.