C8 is not required to inactivate SV5 or MuV. A) Total hemolytic complement activity of NHS, C8-deficient serum, and C8-deficient serum reconstituted with C8 was determined as described in Materials and methods. B) and C) One hundred PFU of SV5 (panel B) or MuV (panel C) were incubated with PBS, 1:25 dilution of NHS, with the indicated dilutions of C8-deficient serum, or C8-deficient serum reconstituted with C8. Remaining infectious titers were determined by plaque assays. Results are the average of six experiments, with error bars representing standard deviations.