FIG. 7.

Subpopulations of Rev differ in phenotype. (A) Nuclear export activity of pony 524 variants (solid bars) and pony 625 variants (striped bars) are reported relative to the activity of R1. Results represent the mean activity of at least 9 independent transfections ± standard error of the mean. Variants that differed significantly from the activity of R1 are indicated; *, P < 0.05; **, P < 0.005; and ***, P < 0.00005. (B) In vitro replication of Rev chimeric virus. Chimeric proviruses representative of clade A/group 1 variants (R53) and clade B/group 2 variants (R1 and R2) were constructed in the backbone of pSPEIAV19. Virus stocks were produced from stably transfected cell lines, normalized by RT activity, and inoculated in duplicate onto equine dermal cells. Supernatant was collected every other day and assayed for virion production by RT activity (8). RT activity was quantified with a phosphorimager, and the results of a representative experiment are shown.