EF1α-Cre-Puro Lentivirus

Lentiviruses belong to the family of retroviridae and are characterized by an RNA genome (ssRNA of 8 to 10 kb) encapsidated with integrase, reverse transcriptase and protease, while the capsid (p24 protein) itself is encapsidated in an envelope composed of host cell membrane lipids (acquired during budding) and viral glycoproteins. In contrast to other retroviruses, lentiviruses are able to infect non-dividing cells, thanks to the access of their pre-integration complex to the nuclear compartment. This property quickly stimulated interest in the development of recombinant lentiviral vectors for gene transfer.

Lentivirus serogroups are divided into five groups, depending on the target vertebrate host. Therefore, the genetic engineering strategy for human immunodeficiency virus type 1 (HIV-1), equine infectious anemia virus (EIAV), simian immunodeficiency virus (SIV), feline immunodeficiency virus (FIV) or bovine immunodeficiency virus (BIV) is the same as that for the development of recombinant vectors of natural viruses. First, a large part of the viral genome (containing genes encoding viral structure and replication processes) is deleted. After several rounds of genetic engineering improvements, the safety of these vectors has been improved, allowing their stable expression in dividing cells. The third generation lentiviral vector (LV) requires four plasmids, of which the transfer plasmid carries the therapeutic cassette. This plasmid contains a sequence template of up to 10 kb of the recombinant genome, consisting of conserved key viral sequences such as the 5′ LTR (long terminal repeat), the 3′ LTR modified to a self-inactivating LTR (SIN), the major splice site donor and acceptor, the packaging signal sequence (Ψ) and the Rev response element (RRE), the nuclear import signal (central polypurine tract, cPPT) and the transgene cassette (foreign sequence to be transferred).