This study demonstrates the use of lentivirus-mediated RNA interference (RNAi) for stable gene silencing in primary cells. The researchers developed a retroviral vector, called Retrohair, which delivers hairpin RNA targeting green fluorescent protein (GFP) to achieve gene silencing. They showed that this system can effectively silence gene expression in transformed cell lines and primary dendritic cells, including the tumor suppressor gene TP53 in normal human fibroblasts. The system was also tested in primary dendritic cells, where it successfully silenced GFP expression. A lentivirus-based vector, Lentihair, was also developed, which showed greater efficiency in gene silencing compared to the Moloney leukemia virus-based vector. The study highlights the potential of lentivirus-mediated RNAi for stable gene silencing in a wide range of cell types, including primary cells, and suggests that this approach could be used to study gene function in various biological systems. The results indicate that lentivirus-delivered RNAi can achieve effective and stable gene silencing, which could be useful for understanding gene function in numerous cell types, including primary cells. The study also shows that the system can be adapted for use in lentiviral systems, allowing for the analysis of gene function in both dividing and non-dividing cells under physiological conditions.This study demonstrates the use of lentivirus-mediated RNA interference (RNAi) for stable gene silencing in primary cells. The researchers developed a retroviral vector, called Retrohair, which delivers hairpin RNA targeting green fluorescent protein (GFP) to achieve gene silencing. They showed that this system can effectively silence gene expression in transformed cell lines and primary dendritic cells, including the tumor suppressor gene TP53 in normal human fibroblasts. The system was also tested in primary dendritic cells, where it successfully silenced GFP expression. A lentivirus-based vector, Lentihair, was also developed, which showed greater efficiency in gene silencing compared to the Moloney leukemia virus-based vector. The study highlights the potential of lentivirus-mediated RNAi for stable gene silencing in a wide range of cell types, including primary cells, and suggests that this approach could be used to study gene function in various biological systems. The results indicate that lentivirus-delivered RNAi can achieve effective and stable gene silencing, which could be useful for understanding gene function in numerous cell types, including primary cells. The study also shows that the system can be adapted for use in lentiviral systems, allowing for the analysis of gene function in both dividing and non-dividing cells under physiological conditions.