FIGURE 4.
Increasing concentrations of ITCH, but not of SMURF-1, rescue the infectivity of HTLV-1 APPY. A, transfections and determination of infectivity were carried out as described in the legend to Fig. 2 using the indicated amounts of pCI-Flag-ITCH or pCI-Flag-SMURF-1. The infectivity of HTLV-1 wt was set to 100%. The results are the average of at least three experiments and the S.D. are shown. B, overexpression of ITCH and SMURF-1 rescues the release of HTLV-1 APPY. Immunoblots of cell and VLP lysates from the above transfection were analyzed with the indicated antibodies. C, ITCH overexpression rescues both the release and morphology of the APPY virions, but SMURF-1 overexpression does not. Representative TEM images of HTLV-1 wt VLP pellets produced by transfection of 5 × 106 293T cells with 5 μg of the indicated HTLV-1 construct and 10 μg of pCI-Flag-ITCH, pCI-Flag-SMURF-1, or empty vector.