TABLE 1.

Viral glycoproteins required for cell fusion, as quantified by an antiluciferase immunoassay^a

Glycoprotein(s) expressed in CHO effector cells	No. of blue cellsb
Vector	3.7 ± 2.9
HHV-8 gB	6.3 ± 5.8
HHV-8 gBMUT	10.3 ± 3.2
HHV-8 gH-gL	28.7 ± 11.6
HHV-8 gB and gH-gL	81.3 ± 21.9
HHV-8 gBMUT and gH-gL	194.3 ± 41.1
HSV-1 gB, gD, and gH-gL	547.3 ± 189.7

^aCHO effector cells were transfected with plasmids expressing the indicated viral glycoproteins and the luciferase reporter plasmid. 293T target cells were transfected with T7 RNA polymerase. Visualization of cells expressing luciferase was done with an antiluciferase immunoassay. Shown are the mean number of blue cells per 500,000 cells and standard deviations from three replicate samples obtained on two separate occasions.

^bMean differences between values for the vector and those for a combination of gB, gH, and gL, for a combination of gB^MUT, gH, and gL, and for a combination of HSV-1 gB, gD, gH, and gL were all statistically significant (P = 0.022, P = 0.008, and P = 0.046, respectively; two-tailed t test). Mean differences between values for the vector and those for gB, gB^MUT, or gH plus gL were not statistically significant (P = 1.0, P = 0.334, and P = 0.134, respectively). Cocultivation of target cells with effector cells expressing only gH or gL resulted in no significant increase in the number of luciferase-expressing cells (data not shown).