Design of non-viral vector with improved regulatory features towards therapeutic application

Design of a Multi-Epitope Vaccine against Tropheryma whipplei Using Immunoinformatics and Molecular Dynamics Simulation Techniques

Whipple’s disease is caused by T. whipplei, a Gram-positive pathogenic bacterium. It is considered a persistent infection affecting various organs, more likely to infect males. There is currently no licensed vaccination available for Whipple’s disease; thus, the development of a chimeric peptide-based vaccine against T. whipplei has the potential to be tremendously beneficial in preventing Whipple’s disease in the future. The present study aimed to apply modern computational approaches to generate a multi-epitope-based vaccine that expresses antigenic determinants prioritized from the core proteome of two T. whipplei whole proteomes. Using an integrated computational approach, four immunodominant epitopes were found from two extracellular proteins. Combined, these epitopes covered 89.03% of the global population. The shortlisted epitopes exhibited a strong binding affinity for the B- and T-cell reference set of alleles, high antigenicity score, nonallergenic nature, high solubility, nontoxicity, and excellent binders of DRB1*0101. Through the use of appropriate linkers and adjuvation with a suitable adjuvant molecule, the epitopes were designed into a chimeric vaccine. An adjuvant was linked to the connected epitopes to boost immunogenicity and efficiently engage both innate and adaptive immunity. The physiochemical properties of the vaccine were observed favorable, leading toward the 3D modeling of the construct. Furthermore, the vaccine’s binding confirmation to the TLR-4 critical innate immune receptor was also determined using molecular docking and molecular dynamics (MD) simulations, which shows that the vaccine has a strong binding affinity for TLR4 (−29.4452 kcal/mol in MM-GBSA and −42.3229 kcal/mol in MM-PBSA). Overall, the vaccine described here has a promising potential for eliciting protective and targeted immunogenicity, subject to further experimental testing.

Delivery of non-viral naked DNA vectors to liver in small weaned pigs by hydrodynamic retrograde intrabiliary injection

Hepatic gene therapy by delivering non-integrating therapeutic vectors in newborns remains challenging due to the risk of dilution and loss of efficacy in the growing liver. Previously we reported on hepatocyte transfection in piglets by intraportal injection of naked DNA vectors. Here, we established delivery of naked DNA vectors to target periportal hepatocytes in weaned pigs by hydrodynamic retrograde intrabiliary injection (HRII). The surgical procedure involved laparotomy and transient isolation of the liver. For vector delivery, a catheter was placed within the common bile duct by enterotomy. Under optimal conditions, no histological abnormalities were observed in liver tissue upon pressurized injections. The transfection of hepatocytes in all tested liver samples was observed with vectors expressing luciferase from a liver-specific promoter. However, vector copy number and luciferase expression were low compared to hydrodynamic intraportal injection. A 10-fold higher number of vector genomes and luciferase expression was observed in pigs using a non-integrating naked DNA vector with the potential for replication. In summary, the HRII application was less efficient (i.e., lower luciferase activity and vector copy numbers) than the intraportal delivery method but was significantly less distressful for the piglets and has the potential for injection (or re-injection) of vector DNA by endoscopic retrograde cholangiopancreatography.

Peptide-Functionalized Dendrimer Nanocarriers for Targeted Microdystrophin Gene Delivery

Gene therapy is a good alternative for determined congenital disorders; however, there are numerous limitations for gene delivery in vivo including targeted cellular uptake, intracellular trafficking, and transport through the nuclear membrane. Here, a modified G5 polyamidoamine (G5 PAMAM) dendrimer-DNA complex was developed, which will allow cell-specific targeting to skeletal muscle cells and transport the DNA through the intracellular machinery and the nuclear membrane. The G5 PAMAM nanocarrier was modified with a skeletal muscle-targeting peptide (SMTP), a DLC8-binding peptide (DBP) for intracellular transport, and a nuclear localization signaling peptide (NLS) for nuclear uptake, and polyplexed with plasmid DNA containing the GFP-tagged microdystrophin (µDys) gene. The delivery of µDys has been considered as a therapeutic modality for patients suffering from a debilitating Duchenne muscular dystrophy (DMD) disorder. The nanocarrier-peptide-DNA polyplexes were prepared with different charge ratios and characterized for stability, size, surface charge, and cytotoxicity. Using the optimized nanocarrier polyplexes, the transfection efficiency in vitro was determined by demonstrating the expression of the GFP and the µDys protein using fluorescence and Western blotting studies, respectively. Protein expression in vivo was determined by injecting an optimal nanocarrier polyplex formulation to Duchenne model mice, mdx^4Cv. Ultimately, these nanocarrier polyplexes will allow targeted delivery of the microdystrophin gene to skeletal muscle cells and result in improved muscle function in Duchenne muscular dystrophy patients.