Project description:Adeno-associated virus (AAV) is a defective mono-stranded DNA virus, endemic in human population (40-80%). AAV infection has long been considered as non-pathogenic1, however few years ago we reported for the first time recurrent clonal AAV2 insertion in the pathogenesis of human hepatocellular carcinoma (HCC) developed on normal liver. These clonal viral insertions target cancer driver genes, including CCNA2, CCNE1, TERT, TNFSF10 and MLL4, leading to their overexpression. The viral inserted sequences involved in almost all the cases the 3’ inverse tandem repeat (ITR) of AAV2, which is important for virus integration in host DNA and exhibits a promoter/enhancer activity. Here, we used RNA sequencing (RNA-seq) to investigate their functional impact on the tissue, such as fusion transcript generation events.
Project description:Retinal Pigment Epithelium (RPE) are crucial for maintaining retinal homeostasis and the visual cycle. Currently, there are no effective treatments for blinding retinal diseases caused by RPE cell degeneration. Gene therapy presents a promising approach, but no gene therapy vectors specifically targeting RPE cells are available. In this study, we utilized an AAV2 random mutation library and high-throughput sequencing to screen AAV vectors (AAV206)capable of specifically targeting RPE cells. Intravitreal injection of the AAV206 vector in mice demonstrated that AAV206 specifically infected RPE cells, whereas AAV2 primarily infects the inner retina. Furthermore, AAV206 exhibited lower immunogenicity and toxicity compared to AAV2. Overexpression of sFLT-1 through AAV206 effectively inhibited the size and leakage of choroidal neovascularization. In summary, AAV206 is an ideal vector for gene therapy targeting RPE cells.
Project description:Hepatocellular carcinomas (HCC) are liver tumors related to various etiologies including alcohol intake, hepatitis B (HBV) or C (HCV) virus infection. Additional risk factors remain to be identified, particularly in patients who develop HCC without cirrhosis. We identified clonal integration of adeno-associated virus type 2 (AAV2) in 11 out of 193 HCC. These AAV2 integrations occurred within known cancer driver genes, namely, CCNA2 (Cyclin A2, 4 cases), TERT (Telomerase Reverse-Transcriptase, 1 case), CCNE1 (Cyclin E1, 3 cases), TNFSF10 (Tumor Necrosis Factor member 10, 2 cases) or KMT2B (Lysine (K)-Specific Methyltransferase 2B, 1 case) leading to over-expression of the target genes. Tumors with viral integration mainly developed in non-cirrhotic liver (9 out of 11 cases) and without known risk factors (6 out of 11) suggesting a pathogenic role of AAV2 in these patients. In conclusion, AAV2 is a DNA virus associated with oncogenic insertional mutagenesis in human HCC.
Project description:We describe and functionally characterize a previously unknown liver-specific enhancer-promoter element in the wild-type AAV2 (wtAAV2) genome lying between the cap stop codon and right-hand inverted terminal repeat (ITR). Remarkably, this element falls within the 163-nucleotide common insertion region of the AAV genome implicated in HCC oncogenesis, thereby providing a mechanistic explanation for the participation of AAV integration events in the development of HCC.
Project description:We have previously developed a modified iteration of a viral chromosome conformation capture (V3C-seq) assay to show that the autonomous parvovirus Minute Virus of Mice (MVM) localizes spatially with cellular sites of DNA damage to establish viral replication centers. Similar V3C-seq assays to map AAV genome localization show that both replicating and non-replicating AAV2 genomes in the absence of helper virus colocalize with cellular sites of DNA damage. The AAV non-structural protein Rep 68/78, when ectopically expressed in the absence of viral infection or during AAV2 infection in the absence of helper proteins also localizes to cellular sites of DNA damage. Strikingly however, recombinant AAV gene therapy vector genomes derived from AAV do not colocalize with AAV and Rep at cellular DDR sites.
Project description:Gene therapy has been adapted, from the laboratory to the clinic, to treat retinopathies. In contrast to subretinal route, intravitreal delivery of AAV vectors displays the advantage of bypassing surgical injuries, but the viral particles are more prone to be nullified by the host neutralizing factors. To minimize such suppression of therapeutic effect, especially in terms of AAV2 and its derivatives, we introduced three serine-to-glycine mutations, based on the phosphorylation sites identified by mass spectrum analysis, to the XL32 capsid to generate a novel serotype named AAVYC5. Via intravitreal administration, AAVYC5 was transduced more effectively into multiple retinal layers compared with AAV2 and XL32. AAVYC5 also enabled successful delivery of anti-angiogenic molecules to rescue laser-induced choroidal neovascularization and astrogliosis in mice and non-human primates. Furthermore, we detected fewer neutralizing antibodies and binding IgG in human sera against AAVYC5 than those specific for AAV2 and XL32. Our results thus implicate this capsid-optimized AAVYC5 as a promising vector suitable for a wide population, particularly those with undesirable AAV2 seroreactivity.
Project description:The human Adeno-Associated Virus serotype 2 (WT AAV2) is a common non-pathological virus and its recombinant form (rAAV) is widely used as gene therapy vector. However, it has been shown that WT AAV2 and recombinant AAV display significantly different characteristics, especially regarding infection rate, with a near perfect infectivity and better encapsidation rate of WT AAV2. Even though rAAVs are routinely produced in the Baculovirus/Sf9 cell system, WT AAV2 has never been produced in this context. To understand the infectivity and encapsidation rate differences between WT AAV2 and rAAV, we tried to produce WT AAV2 in baculovirus/Sf9 cells system hypothesizing that the WT AAV2 may be considered as a normal recombinant AAV transgene. Through our attempts to produce WT AAV2 in Baculovirus/Sf9, we found that WT AAV2 p5 promoter, which controls the expression of large Rep proteins in mammalian cells, was active in this system. p5 promoter activity in the baculovirus/Sf9 cell system led to the expression of Rep78 that finally excises WT AAV2 genome from the baculovirus genome during the earliest phase of baculovirus stock production. The p5 promoter expression kinetics and the specific strand RNA-Seq analysis of the WT AAV2, rAAV Rep2/Cap2 cassettes in the baculovirus context was performed. We demonstrate that the WT AAV2 native promoters, p5, p19 and p40 are all active and lead to the expression of different proteins and peptides. In addition, this study demonstrates that the baculovirus brings at least some of the helper functions needed in the AAV replication/life cycle.
Project description:In order to identify the subset of genes directly regulated by Foxa2 in the liver, we performed genome-wide location analysis. Chromatin immunoprecipitation (ChIP) samples from livers of wild type and Foxa2 liver-conditional null mice (Foxa2loxP/loxPAlfp.Cre) were hybridized to a mouse enhancer/promoter microarray with more than 36,000 elements (BCBCPromChip 5). This analysis identified 574 enhancer and promoter regions, corresponding to 484 unique genes, as occupied by Foxa2 in the adult liver.
Project description:Massively parallel reporter assays (MPRA) are widely used to discover functional enhancers but have largely been limited to transfected cell models. Here, we combine hydrodynamic injection with a modified STARR-seq-based MPRA to determine condition-specific enhancer activity in mouse liver at scale, and we examine how different promoters affect STARR-seq reporter activity. Strong liver enhancer activity was observed with STARR-seq libraries containing an Albumin minimal promoter but not when using a Super Core promoter or an origin of replication (ORI) promoter. This work is part of a larger study where we prepare a global STARR-seq library, comprised of ~50,000 genomic sequences released by DNase-I digestion of mouse liver nuclei, and where we identify condition-specific enhancers with strong correlations between liver enhancer activity and the chromatin state of the corresponding endogenous genomic regions.
Project description:Massively parallel reporter assays (MPRA) are widely used to discover functional enhancers but have largely been limited to transfected cell models, which are confounded by vector-induced innate immune responses and lack the physiologically relevant cellular and endogenous hormonal context and chromatin environment of complex mammalian tissues. Here, we combine hydrodynamic injection with a modified STARR-seq-based MPRA to determine condition-specific enhancer activity in mouse liver at scale. Strong liver enhancer activity was observed with STARR-seq libraries containing an Albumin minimal promoter but not when using a Super Core promoter or an origin of replication promoter. Analysis of a global STARR-seq library, comprised of ~50,000 genomic sequences released by DNase-I digestion of mouse liver nuclei, identified condition-specific enhancers and revealed strong correlations between liver enhancer activity and the chromatin state of the corresponding endogenous genomic regions.