Inducible expression of the ΔNGFr/F12Nef fusion protein as a new tool for anti-human immunodeficiency virus type 1 gene therapy

Expression of the human immunodeficiency virus type 1 (HIV-1) Nef triple mutant F12Nef strongly inhibits HIV-1 replication. We exploited such a unique feature in a novel anti-HIV-1 gene therapy design by constructing an HIV-1 Tat-defective lentivirus vector expressing the product of fusion between the low-affinity human nerve growth factor receptor truncated in its intracytoplasmic domain (DeltaNGFr, NH2 moiety), and F12Nef (COOH moiety), under the control of the HIV-1 long terminal repeats. In this manner, both the selection marker (DNGFr) and the anti-HIV-1 effector are comprised in the same fusion protein, the expression of which is targetable by HIV-1 infection. Such a vector was proved to transduce human cells efficiently and, on HIV-1 infection, it expressed high levels of the fusion protein. In addition, strong antiviral activity of the DNGFr/F12Nef-expressing vector was demonstrated in cell lines as well as in primary cell cultures challenged with T- or M-tropic HIV-1 isolates. Thus, the HIV-1-targetable expression of the DeltaNGFr/F12Nef fusion protein represents a novel and powerful tool for an effective anti-HIV-1 gene therapy strategy.