Use Of Adeno-associated Vectors Research Articles

Understanding Hepatic Porphyrias: Symptoms, Treatments, and Unmet Needs.

Hepatic porphyrias are a group of metabolic disorders that are characterized by overproduction and accumulation of porphyrin precursors in the liver. These porphyrins cause neurologic symptoms as well as cutaneous photosensitivity, and in some cases patients can experience life-threatening acute neurovisceral attacks. This review describes the acute hepatic porphyrias in detail, including acute intermittent porphyria, hereditary coproporphyria, and variegate porphyria, as well as the hepatic porphyrias with cutaneous manifestations such as porphyria cutanea tarda and hepatoerythropoietic porphyria. Each section will cover disease prevalence, clinical manifestations, and current therapies, including strategies to manage symptoms. Finally, we review new and emerging treatment modalities, including gene therapy through use of adeno-associated vectors and chaperone therapies such as lipid nanoparticle and small interfering RNA-based therapeutics.

Viral Vectors in Transgenic Research: Prospects for the Treatment of CNS Diseases and Gene Therapy

Viral vectors are of great clinical interest due to their high efficiency, which allows them to find practical applications in gene therapy. The review presents current research data on various fish species as potential models for the use of viral vectors. During the study of high-performance adenoviral vectors data on the stable expression of transgenes in the body of Danio rerio and other fish species was obtained. The features of the use of adeno-associated vectors in the study of transneuronal transfer of the glucuronidase protein in the projection neurons of the ventral tegmental area and striatum to treat metabolic insufficiency in case of mucopolysaccharidosis VII are considered. Taking into consideration the wide set of genetically modified Danio rerio strains, ethical aspects, and the acceptability of applying this model in neurogenic studies, it is clear that Danio rerio, as well as other fish species, can be used as an alternative for early preclinical evaluation of the efficiency of viral vectors.

Selective Anti-AAV Antibody Depletion by Hemapheresis and Immunoadsorption.

One of the greatest barriers for the use of adeno-associated vectors (AAV) in gene therapy is the presence of pre-existing antibodies against AAV in the general population. Since many of the anti-AAV antibodies have the ability to neutralize the transduction target tissues, even patients with low antibody titers must be excluded from clinical trials or therapy. In recent years, various methods have been proposed to overcome this problem, unfortunately with limited success. In this chapter, we describe in detail a protocol for hemapheresis with an immunoadsorption matrix to remove specifically anti-AAV antibodies in an in vivo rat model. Furthermore, this chapter describes in detail the methods to determine the efficiency of hemapheresis and immunoadsorption.

Efficient In Utero Gene Transfer to the Mammalian Inner Ears by the Synthetic Adeno-Associated Viral Vector Anc80L65

Sensorineural hearing loss is one of the most common sensory disorders worldwide. Recent advances in vector design have paved the way for investigations into the use of adeno-associated vectors (AAVs) for hearing disorder gene therapy. Numerous AAV serotypes have been discovered to be applicable to inner ears, constituting a key advance for gene therapy for sensorineural hearing loss, where transduction efficiency of AAV in inner ear cells is critical for success. One such viral vector, AAV2/Anc80L65, has been shown to yield high expression in the inner ears of mice treated as neonates or adults. Here, to evaluate the feasibility of prenatal gene therapy for deafness, we assessed the transduction efficiency of AAV2/Anc80L65-eGFP (enhanced green fluorescent protein) after microinjection into otocysts in utero. This embryonic delivery method achieved high transduction efficiency in both inner and outer hair cells of the cochlea. Additionally, the transduction efficiency was high in the hair cells of the vestibules and semicircular canals and in spiral ganglion neurons. Our results support the potential of Anc80L65 as a gene therapy vehicle for prenatal inner ear disorders.

Improving clinical efficacy of adeno associated vectors by rational capsid bioengineering.

Adeno associated vectors (AAV) have shown considerable promise to treat various genetic disorders in both preclinical and clinical settings mainly because of its safety profile. However, efficient use of AAV to deliver genes in immune-competent sites like muscles and liver requires very high doses which are associated with concomitant cellular immune response against the viral capsids leading to destruction of the transduced cells. Coupled with that, there are enough evidences that at high doses, AAV particles are subjected to increased cellular phosphorylation/uniquitination leading to proteasome mediated degradation and loss of the viral particles. The presence of preexisting immunity against AAV further adds on to the problem which is acting as a major roadblock to efficiently use it as a gene therapy vector in the clinics. To overcome this, rational bioengineering of AAV capsid becomes a prime tool by which specific amino acid residue(s) can be suitably modified/replaced by compatible residue(s) to create vectors having lower host immune response and higher intracellular trafficking rate. This article reviews the various aspects of rationally designing AAV capsids like by site-directed mutagenesis, directed evolution and combinatorial libraries which can create vectors having not only immune evasive property but also enhanced gene expression and transduction capability. One or more combinations of these strategies have strong potential to create novel vectors which will have suitable clinical efficiency even at a low dose.