Wednesday, February 5, 2025
2/5/2025
A higher prevalence of chronic hepatitis B virus (HBV), 7.4% globally and 15 to 28% in highly endemic areas, is observed in people living with HIV (PLWH). While current combined antiretroviral therapy (cART) can restrict HBV/HIV replication, cART cannot eliminate the HIV/HBV DNAs that are integrated into the host genome. As such, HBV and HIV persist in cART-controlled individuals, and cART cessation readily leads to viral reactivation and disease progression. Thus, any curative strategy should include a means to eliminate integrated viral DNA from the reservoir cells that harbor HIV and/or HBV (HBV/HIV) DNA without collateral cytotoxic reactions. CRISPR (clustered regularly interspaced short palindromic repeats) Cas9 (CRISPR-associated protein 9)-mediated gene editing is an appealing approach to tackle this problem. The keys to success in the CRISPR/Cas9 approach are to select virus-specific target genes that are critical for viral replication yet avoid off-target effects on the human genome and ensure efficient delivery of the gene-editing drugs to target cells. The current CRISPR/Cas9 delivery technologies often require viral vectors, which pose safety concerns for therapeutic applications in humans. Synthetic Cas9-ribonucleoprotein (RNP) is an attractive non-viral formulation for the CRISPR/Cas9 system due to its quick DNA cleavage activity, low frequency of off-target effects, low risk of insertional mutagenesis, easy production, and readiness for clinical application. However, existing non-viral strategies for Cas9-RNP delivery face a number of challenges, such as high cytotoxicity, poor in vivo stability, large particle sizes, lack of specific tissue- and/or cell-targeting abilities, variable loading of the RNP cargo, and potential immunogenicity. These challenges limit the application of Cas9-RNP for in vivo systemic application. Therefore, advances in the discovery of novel interventions targeting incorporated viral DNA are urgently needed for the cure of HBV/HIV co-infection. To address these needs, we have: 1) selected specific HBV/HIV target genes that are crucial for viral replication but share no overlap with (off-targeting) the human genome; 2) synthesized guide-RNAs (gRNA) and Cas9-RNP as therapeutic drugs; 3) developed novel nanoparticles (NP) with longer cleavable polyethylene glycol (PEG) arms to decorate the HBV/HIV gRNA-Cas9 RNP and slow the release of the prodrug intracellularly; and 4) established HBV/HIV cellular models to test the efficacy and cytotoxicity of our generated HBV/HIV gRNA-RNP. In this study, we will test our newly designed gene editing drugs that target viral DNA but not the human genome using HBV/HIV cellular models. We hypothesize that specific CRISPR/Cas9 gene editing drugs will abolish HBV/HIV replication and elicit minimum cytotoxicity in these cellular models. We propose two specific aims to test our hypothesis: Aim 1 will screen and test CRISPR/Cas9 gene editing drugs using a nucleofection approach in our cellular HBV/HIV models; Aim 2 will generate and test HBV/HIV gRNA-Cas9 NPs and compare their efficacy and cytotoxicity in our cellular HBV/HIV models. The objectives of this project are to collect critical information, establish new techniques, and lay the foundation for achieving our long-term goal of discovery a cure for HBV/HIV co-infection.
HHS’ Tracking Accountability in Government Grants System (TAGGS) website provides access to detailed descriptions of grants, loans, aggregated direct payments and other types of financial assistance awarded by the HHS Operating Divisions (OPDIVs) and the Office of the Secretary Staff Divisions (STAFFDIVs).