FIG. 7.

Efficient cell fusion requires HHV-8 gB and gH-gL. CHO effector cells were transfected with plasmids expressing the indicated glycoproteins or a control vector and the luciferase reporter plasmid. 293T target cells were transfected with T7 RNA polymerase. After cocultivation for 24 h, luciferase activity was measured. Shown are the mean relative luminosity units (RLU) and standard deviations for six replicate samples obtained on two separate occasions. Mean differences between values for the vector and those for gB^MUT, gH plus gL, a combination of gB, gH, and gL, or a combination of gB^MUT, gH, and gL were all statistically significant (P < 0.001; two-tailed t test). The difference between the vector and gB values was also statistically significant (P = 0.012). Additional experiments done independently resulted in similar findings (data not shown). For comparison, cocultivation of 293T cells with CHO effector cells expressing HSV-1 glycoproteins gB, gD, and gH-gL resulted in a mean RLU of 226.2.