TABLE 1.

Syncytium formation induced by ADA Env mutants^a

Clone	No. of syncytia	No. of nuclei/syncytium (range)
Wild type	5,833 ± 465	2–30
FivA	0
SivA	0
t35A	0
p34A	809 ± 322	2–5
t7A	912 ± 173	2–5
t24A	1,859 ± 553	2–5
t25A	2,207 ± 323	2–5

^a293T cells plated in six-well plates were transfected in triplicate with ADA wild-type Env or Env mutants. After coculturing with HeLa P5 cells (CD4⁺ CCR5⁺), fusion events were detected by β-galactosidase staining. Syncytia were counted independently by two investigators using a grid (486 squares/well). Mean ± standard deviation numbers of syncytia in three wells are shown. In three wells with mock-transfected cells, there were fewer than 10 syncytia. The syncytium-forming capacities of the t2A and t9A mutants were analyzed in separate experiments. The percentages of syncytia were approximately 10 and 3% (for t2A and t9A, respectively) that found with wild-type Env.