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 (ΔNGFr, NH2 moiety), and F12Nef (COOH moiety), under the control of the HIV-1 long terminal repeats. In this manner, both the selection marker (ΔNGFr) 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 ΔNGFr/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-targeta...