Transcription proceeds through the genome and mRNA is polyadenylated and processed using signals in transcribed regions from the 3' LTR at the end of the transcribed R. The full-length message can be spliced to lead to production of envelope proteins (or other proteins depending upon retroviral class). Unspliced full-length mRNA can give rise to gag-pol proteins. Gag and Pol are made as either Gag protein or a Gag-Pol precursor. A viral protease cleaves the precursor into multiple subunits with varying functions. The Env protein is also translated as a precursor which is cleaved by endogenous proteases to yield the mature surface glycoprotein (see below).

Translated proteins assemble a retroviral particle at the cell surface. Full-length genomic unspliced mRNA (containing a packaging signal termed Psi) is bound by gag-derived proteins and incorporated into the budding particle.