Human papillomavirus 11 E5A delays the growth restriction induced by temperature shift in temperature-sensitive simian virus 40 T antigen-immortalized keratinocytes

The transfection with human papillomavirus type II E5a oncoprotein can cause longer and more active proliferation in the human keratinocytes previously transfected stably with temperature sensitive SV40 T antigen at 39°C, Also, after the E5a transfection in parental temperature sensitive SV40 T antigen gene transfected cells, we observe a delay in the accumulation of p21 gene at 39°C. Moreover, T antigen degradation did not occur at 39°C in the E5a transfected cells as it did in the parental cells. We draw from these observations that E5a may transiently stabilize temperature sensitive T antigen and/or repress p21 synthesis.