Recombinant human interferons inhibit replication of Mason-Pfizer monkey virus in primate cells

Pretreatment of Mason-Pfizer monkey virus-infected human embryonic kidney cells with either of the cloned human interferons, A or A/D, reduces the release of infectious virus particles to the same extent (greater than 97%) as determined by 125I-protein A binding radioimmune assay. While interferon A has no significant effect on the release of infectious viruses from a Mason-Pfizer monkey virus-infected monkey cell line consistent with the species specificity of this group of compounds, human interferon A/D can block the release of virions from the same monkey cell line. This block appears to be at the level of viral particle release from the cells since both labeling with radioactive precursors and electron microscopic observations show few extracellular particles but normal levels of intracytoplasmic A particles. The results show that cloned human interferon A/D can block the replication of an immunosuppressive retrovirus in primate cells and raise the possibility of testing the efficacy of this interferon in primate model systems.