FIG. 3.

The K74R mutation decreases, but does not abolish, virus release. (A) The amounts of MA-reactive material in cell extracts and supernatants were determined by HTLV-1 p19(MA) ELISA. The percentage of the total MA released into the supernatants is shown for 293T cells transfected with pCMVHT-1ΔX (WT), pCMVHT-1ΔX-P3G, pCMVHT-1Δ-K74R, pCMVHT-1ΔX-3KR, or pCMVHT-1ΔX-4KR. The graph summarizes three independent experiments. (B) VLPs produced after transfection of 293T cells with the indicated HTLV-1 expression vectors were examined in single-cycle replication assays. Infectivity is represented relative to total MA protein in the culture, and the value for pCMVHT-1ΔX was set at 100%; error bars indicate standard deviations.