%0 Journal Article %A Dawson, K. M. %A Stewart, A. %A Stebbing, N. %T Absence of Significant Antiviral Effects of β-γ-Methylene GTP on Encephalomyocarditis Virus Infection of L cells and Mice %D 1979 %J Journal of General Virology, %V 45 %N 1 %P 237-240 %@ 1465-2099 %R https://doi.org/10.1099/0022-1317-45-1-237 %I Microbiology Society, %X SUMMARY The protein synthesis inhibitor β-γ-methylene guanosine triphosphate (Gpp-CH2p) is shown here to be ineffective as a ‘leaky membrane’ antiviral agent against encephalomyocarditis virus infection of L cells and mice. Studies with GppCH2p in encephalomyocarditis virus-infected L cells indicate that the cells only become permeable to the inhibitor late in infection because the compound significantly inhibits protein synthesis only when added at 4 h p.i. At this time 50 to 70% of the new infectious virus particles have already been synthesized, and this is reflected in maximum inhibition of virus yields of only about 40%. Moreover, comparison of inhibition of protein synthesis by GppCH2p in vitro and in cell cultures indicates that the intracellular concentration attained is only 0.25% of that in the medium. The lack of antiviral activity of GppCH2p in encephalomyocarditis virus-infected mice is probably due to leakiness of infected cells occurring too late for sufficient inhibition of virus synthesis to be obtained. %U https://www.microbiologyresearch.org/content/journal/jgv/10.1099/0022-1317-45-1-237