Multigenic lentiviral vectors for combined and tissue-specific expression of miRNA- and protein-based antiangiogenic factors.

Lentivirus-based gene delivery vectors carrying multiple gene cassettes are powerful tools in gene transfer studies and gene therapy, allowing coexpression of multiple therapeutic factors and, if desired, fluorescent reporters. Current strategies to express transgenes and microRNA (miRNA) clusters from a single vector have certain limitations that affect transgene expression levels and/or vector titers. In this study, we describe a novel vector design that facilitates combined expression of therapeutic RNA- and protein-based antiangiogenic factors as well as a fluorescent reporter from back-to-back RNApolII-driven expression cassettes. This configuration allows effective production of intron-embedded miRNAs that are released upon transduction of target cells. Exploiting such multigenic lentiviral vectors, we demonstrate robust miRNA-directed downregulation of vascular endothelial growth factor (VEGF) expression, leading to reduced angiogenesis, and parallel impairment of angiogenic pathways by codelivering the gene encoding pigment epithelium-derived factor (PEDF). Notably, subretinal injections of lentiviral vectors reveal efficient retinal pigment epithelium-specific gene expression driven by the VMD2 promoter, verifying that multigenic lentiviral vectors can be produced with high titers sufficient for in vivo applications. Altogether, our results suggest the potential applicability of combined miRNA- and protein-encoding lentiviral vectors in antiangiogenic gene therapy, including new combination therapies for amelioration of age-related macular degeneration

Lack of immunological DNA sensing in hepatocytes facilitates hepatitis B virus infection.

Hepatitis B virus (HBV) is a major human pathogen and about one third of the global population will be exposed to the virus in their life time. HBV infects hepatocytes where it replicates its DNA and infection can lead to acute and chronic hepatitis with high risk of liver cirrhosis and hepatocellular carcinoma. Despite this, there is limited understanding of how HBV establishes chronic infections. In recent years it has emerged that foreign DNA potently stimulates the innate immune response, particularly type I IFN production, and this occurs through a pathway dependent on the DNA sensor cGAS and the downstream adaptor protein STING. In this work we describe that human and murine hepatocytes do not express STING. Consequently, hepatocytes do not produce type I IFN in response to foreign DNA or HBV infection and mice lacking STING or cGAS exhibit unaltered ability to control infection in an adenovirus-HBV model. Stimulation of IFN production in the murine liver by administration of synthetic RNA decreases virus infection, thus demonstrating that IFN possess anti-HBV activity in the liver. Importantly, introduction of STING expression specifically in hepatocytes reconstitutes the DNA sensing pathway, which leads to improved control of HBV in vivo. In conclusion, the lack of a functional innate DNA sensing pathway in hepatocytes hampers efficient innate control of HBV infection. This may explain why HBV has adapted to specifically replicate in hepatocytes, and could contribute to the weak capacity of this cell type to clear HBV infection