Figure 6.

HTLV-1 RNA packaging efficiency of the WT and mutant HT-UTR-MA RNA. A, serial dilution of the HTLV-1–like particles for protein quantification. Top, immunoblot displaying a serial dilution (1–20 μl of lysate per loading) of HTLV-1–like particles. Bottom, protein band intensities (in arbitrary units) (y axis) were plotted against the volume of protein loaded (x axis) to evaluate the linearity and accuracy of protein quantification. The linear equation and an R² value are indicated. B, immunoblots of both VLPs and cell lysates were probed with anti-HA antibodies, and cell lysate blots were normalized for expression based upon glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The amount of protein was determined based on the linear standard shown in A. Lane 1, WT HT-UTR-MA; lane 2, M348 mutant; lane 3, M382 mutant; lane 4, 2M mutant. C, relative expression level of WT or mutant HT-UTR-MA RNAs in VLPs as detected by a two-step quantitative RT-PCR assay. The expression level of the M348, M382, and 2M mutants was normalized to that from WT HT-UTR-MA. The results of four independent experiments are shown with the mean value indicated by a horizontal bar. D, relative -fold change of RNA packaging efficiency. The RNA packaging efficiency (y axis) was calculated as indicated under “Experimental procedures.” The RNA packaging efficiency of the M348, M382, and 2M mutants was normalized to that from WT HT-UTR-MA. The results of four independent experiments are shown with the mean value indicated by a horizontal bar. n.s., no significant difference.