Decrease of sensitivity to cell-growth inhibitory effect of interferon in human embryo cells after infection with SV40.

No changes in sensitivity of human embryo cells (HEC) to the antiviral action of interferon early (i.e. up to 17 days) after infection with simian virus 40 (SV40) could be detected. At the same time the sensitivity of cells to the cell-growth inhibitory effect of interferon decreased considerably. The changes in sensitivity of HEC to interferon action occurred during 5 successive passages following the infection with SV40 and remained on a similar level thereafter. During this period, no morphological alterations of cells were observed.