FIG. 1.

Kinetics of viral DNA synthesis and influence of temperature upshift. A series of petri dishes (10 cm²) with approximately one million Vero cells each was infected with viruses at an MOI of 10. After incubation at the permissive temperature of 33°C for the time in hours shown on the abscissas, cells together with the culture media were harvested and frozen at −70°C. Total DNA was isolated, aliquots were applied to nitrocellulose membranes, and HSV-specific sequences were quantitated by dot hybridization (21) with a radioactively labeled HSV-1 DNA probe. Signals were calculated as genome equivalents and are symbolized by open circles (○) in the diagrams, which represent the kinetics of the accumulation of viral DNA at the permissive temperature. A parallel series of cell cultures was infected identically, yet after initial incubations at the permissive temperature for the shown periods of time, individual cultures, instead of being harvested immediately, were transferred to the nonpermissive temperature (39°C). The time points of these transfers (upshift) are symbolized by filled triangles (▴). The upshifted cultures were finally harvested altogether at 30 h p.i. Total DNA was isolated and HSV-specific DNA was quantitated as described for the aforementioned samples. The HSV genome equivalents of the shift kinetics experiment are also symbolized by the filled triangles.