GROWTH CHARACTERISTICS OF REOVIRUS TYPE-2 - ULTRAVIOLET LIGHT INACTIVATED VIRION PREPARATIONS AND CELL DEATH

Ultraviolet light inactivated preparations of purified reovirus type 2 when added to monolayers of HeLa cells have been found to cause a cytotoxic effect (CTE). At multiplicities of 80-100 infectious units per cell (IU/cell) cellular death due to CTE was initially observed at 3-4 hours post infection and reached maximum 9-10 hours after infection. The cell survival curves suggest that the rate of cell killing was dependent upon the multiplicity of infection and exhibited multiple hit type of kinetics. The CTE was preceded by marked alterations in the synthesis of cellular RNA, DNA, and protein, and not produced by UV-irradiated preparations of uninfected HeLa cell homogenates nor by UV-R2 preparations heated at 56°C for 30 minutes. When UV-R2 preparations were subjected to ultracentrifugation (45,000 r.p.m., 1.5 hours), activity was restricted to the sediment only. In addition, CTE could not be serially transferred and could be prevented by addition of reovirus type 2 antiserum. The data strongly suggest that the toxic factor is an intimate part of the UV-inactivated viral particle. © 1969 Springer-Verlag.