...one plasmid: Gag, Pol, Rev, Tat Two plasmids: one encoding Gag and Pol and another encoding Rev Envelope... split into two plasmids: one encoding Rev and one encoding Gag and Pol. Although safer, this system can...express the HIV gag, pol, rev, and tat genes all from a single packaging plasmid such as psPAX2 . 3rd generation...system contains a single packaging plasmid encoding the Gag, Pol, Rev, and Tat genes. The transfer plasmid... Interchangeable: usually encodes for VSV-G Interchangeable: usually encodes for VSV-G Safety Safe. Replication...Replication incompetent: Uses 3 separate plasmids encoding various HIV genes. Safer. Replication incompetent and...generation packaging systems: express gag and pol from one packaging plasmid and rev from another, such...