Assembly and budding
The Gag and Gag-Pol precursor proteins traffic to the cytoplasmic membrane and direct budding of the nascent viral particle. A collection of host cell factors important in intracellular membrane vesicle trafficking are recruited to assist viral budding . The Env protein traffics through the endoplasmic reticulum/Golgi system to the cell surface, and associates with particles at sites of budding. The budding process is completed by severing the membranes at the site of budding, so that the viral and cellular lipid bilayers become continuous and separate.
The final step of viral particle formation is maturation. The immature viral particle contains Gag and Gag-Pol in an annular arrangement just under the viral membrane. Action of the viral protease (right) cleaves Gag into the constituent MA, CA, and NC, and Pol into PR, RT, and IN. Associated with these cleavage events, the core assumes the mature bullet-shaped structure characteristic of lentivirses. The mature particle is then capable of initiating infection in new target cells.
For review see: 
- von Schwedler UK, Stuchell M, Muller B, Ward DM, Chung HY, Morita E, Wang HE, Davis T, He GP, Cimbora DM et al. 2003. The protein network of HIV budding. Cell 114: 701-713.
- Sundquist WI, Krausslich HG. 2012. HIV Assembly, Budding, and Maturation, in HIV From Biology to Prevention and Treatment, pp. 95 Cold Spring Harbor Laboratory Press, Cold Spring Harbor.