Human Immunodeficiency Virus Type 1 Escapes from RNA Interference-Mediated Inhibition

Abstract

Short-term assays have suggested that RNA interference (RNAi) may be a powerful new method for intracellular immunization against human immunodeficiency virus type 1 (HIV-1) infection. However, RNAi has not yet been shown to protect cells against HIV-1 in long-term virus replication assays. We stably introduced vectors expressing small interfering RNAs (siRNAs) directed against the HIV-1 genome into human T cells by retroviral transduction. We report here that an siRNA directed against the viral Nef gene (siRNA-Nef) confers resistance to HIV-1 replication. This block in replication is not absolute, and HIV-1 escape variants that were no longer inhibited by siRNA-Nef appeared after several weeks of culture. These RNAi-resistant viruses contained nucleotide substitutions or deletions in the Nef gene that modified or deleted the siRNA-Nef target sequence. These results demonstrate that efficient inhibition of HIV-1 replication through RNAi is possible in stably transduced cells. Therefore, RNAi could become a realistic gene therapy approach with which to overcome the devastating effect of HIV-1 on the immune system. However, as is known for antiviral drug therapy against HIV-1, antiviral approaches involving RNAi should be used in a combined fashion to prevent the emergence of resistant viruses.

Gene therapy progress and prospects: Novel gene therapy approaches for AIDS

“…40 In a recent study siRNA targeting the Nef gene did confer resistance to HIV-1 replication; nevertheless, HIV-1 variants appear that are immune to interference owing to nucleotide substitutions or deletions within the Nef gene. 41 RNAi should therefore be used in combination with other strategies in order to prevent the appearance of resistant viruses. 41 Other studies have targeted the cellular genes involved in the viral life cycle.…”

“…41 RNAi should therefore be used in combination with other strategies in order to prevent the appearance of resistant viruses. 41 Other studies have targeted the cellular genes involved in the viral life cycle. In this case, the question is whether silencing of host genes will have detrimental effects on the cells.…”

Effective Suppression of Human Immunodeficiency Virus Type 1 through a Combination of Short- or Long-Hairpin RNAs Targeting Essential Sequences for Retroviral Integration

“…Antiviral therapy based on siRNA has been proposed as a new method for intracellular immunization against human immunodeficiency virus type 1 (HIV-1) (16,31,32) and hepatitis C virus (HCV) (34). When viral genes are targeted, viruses can escape from RNAi-mediated inhibition due to their high mutation rate (6,11,39). An alternative approach that shows promise is the use of siRNAs targeting cellular genes essential for virus replication.…”

“…These regions include the primerbinding site, the polypurine tract, the long terminal repeat, and the gag, pol, env, tat, rev, vif, and nef genes (6,10,11,16,18,21,30,39). The degree to which siRNAs inhibited HIV-1 replication and the underlying mechanisms varied considerably, depending on the target sequence (10,11). For example, RNAiresistant HIV-1 variants can emerge not only through mutations in the siRNA target sequence but also through mutations that alter the local RNA structure (39).…”

RNA interference and HIV‐1 infection

“…These studies involved both transient transfection with siRNAs and stable expression of short hairpin RNAs (shRNAs) [37]. Several HIV genes have been targeted, including gag, pol, vif, tat, rev, env and nef genes and the LTR region [36,49,55,[108][109][110][111]. In view of the essential roles of these genes in the HIV replication cycle, regulatory genes such as rev and tat might be attractive targets for RNAi-based antiviral therapies.…”