Complex sentence: The spliced RNA are used to produce tat, rev, and nef proteins; the incompletely-spliced RNAs are exported using Rev; the unspliced ful-length viral RNA is translated into Env, Gag and Gag-Pol polyproteins.
Split into simpler sentences: The spliced RNA are used to produce tat, rev, and nef proteins. The unspliced full-length viral RNA is translated into Env, Gag and Gag-Pol polyproteins.