FIG. 6.

Genomic and spliced RNA levels in cells and virus particles of wtzip and MS2 HIV-1 constructs. Aliquots of cellular and viral RNA samples prepared from transfected cells and virus pellets, as described in Materials and Methods, were mixed with 10 μg of yeast tRNA, ethanol precipitated, dried, and hybridized to an HIV-1 antisense probe of 183 nt (lanes 6 and 14), which crosses the HIV-1 major splice donor site. Following the RNase protection described in Materials and Methods, the probe is capable of detecting both spliced viral transcripts at a fragment size of 63 to 64 nt and unspliced, genomic RNAs at a protected fragment size of 150 nt. Results from mock reactions using yeast tRNA samples alone were used (lanes 5 and 13). Note that viral RNA signals were normalized for total Gag protein content to yield encapsidation efficiencies as indicated in Results.