Figure 1.

Lentiviral plasmids and the principle of production of lentiviral vectors. The genetic information necessary for the production of LVs is distributed over at least three distinct plasmids. The packaging plasmid contains gag, pol, tat, and rev genes. The envelope plasmid encodes VSV-G. These elements are under the transcriptional control of the cytomegalovirus promoter (P_CMV). The transfer plasmid contains the Ψ packaging signal, RRE, and cPPT/CTS cis-acting elements upstream of the transgene of vaccinal interest under an internal promoter of choice. At its 3′ untranslated region, this plasmid also harbors the mutated WPRE sequence (WPREm), which enhances transgenic antigen expression. In the transfer plasmid, these genes are flanked by two LTRs. LV particles are generated by the tripartite transfection of the HEK293T cell line with the three plasmids. The LV particles are harvested in the culture supernatants at day 3 post-transfection.