Additionally, some of the AAV evolution technologies discussed above have been used to identify AAVs that are resistant to the effects of NAbs [50, 57]. is usually a versatile viral vector technology that can be engineered for very specific functionality in gene therapy applications.To date, AAV has been shown to be safe and effective in preclinical and clinical settings.AAV can be used in a wide range of clinical applications in multiple diseases due its unique biological and biophysical properties. Open in a separate window Introduction The Ansamitocin P-3 discovery of DNA as the biomolecule of genetic inheritance and disease opened up the prospect of therapies in which mutant, damaged genes could be altered for the improvement of the human condition. The recent ability to rapidly and affordably perform human genetics on hundreds of thousands of people, and to sequence complete genomes, has resulted in an explosion of nucleic acid sequence information and has allowed us to identify the gene, or genes, that might be driving a particular disease state. If the mutant gene(s) could be fixed, or if the expression of overactive/underactive genes could be normalized, the disease could be treated at the molecular level, and, in best case scenarios, potentially be cured. This concept seems particularly true for the treatment of monogenic diseases, i.e. those diseases caused by mutations in a single gene. This seemingly simple premise has been the goal of gene therapy for over 40?years. Until relatively recently, that simple goal was very elusive as technologies to safely deliver nucleic acid cargo inside cells have lagged behind those used to identify disease-associated genes. One of the earliest approaches investigated was the use of viruses, naturally occurring biological brokers that have evolved to do one thing, i.e. deliver their nucleic acid (DNA or RNA) into a host cell for replication. There are numerous viral agents that could be selected for this purpose, each with some unique attributes that would make them more or less suitable for the task, depending on the desired profile [1]. However, the undesired properties of some viral vectors, including their immunogenic profiles or their propensity to cause cancer have resulted in Rabbit Polyclonal to ADA2L serious clinical adverse events and, until recently, limited their current use in the clinic to certain applications, for example, vaccines and oncolytic strategies [2]. More artificial delivery technologies, such as nanoparticles, i.e. chemical formulations meant to encapsulate the nucleic acid, safeguard it from degradation, and get through the cell membrane, have also achieved some levels of preclinical and clinical success. Not surprisingly, they also have encountered some unwanted safety signals that need to Ansamitocin P-3 be better comprehended and controlled [3]. Adeno-associated virus (AAV) is one of the most actively investigated gene therapy vehicles. It was initially discovered as a contaminant of adenovirus preparations [4, 5], hence its name. Simply put, AAV is usually a protein shell surrounding and protecting a small, single-stranded DNA genome of approximately 4.8?kilobases (kb). AAV belongs to the parvovirus family and is dependent on co-infection with other viruses, mainly adenoviruses, in order to replicate. Initially distinguished serologically, molecular cloning of AAV genes has identified hundreds of unique AAV strains in numerous species. Its single-stranded genome contains three genes, (Replication), (Capsid), and (Assembly). These three genes give rise to at least nine gene products through the use of three promoters, alternative translation start sites, and differential splicing. These coding sequences are flanked by inverted terminal repeats (ITRs) that are required for genome replication and packaging. The gene encodes four proteins (Rep78, Rep68, Rep52, and Rep40), which are required for viral genome replication and packaging, while expression gives rise to the viral capsid proteins (VP; VP1/VP2/VP3), which form the outer Ansamitocin P-3 capsid shell that protects the viral genome, as well as being actively involved in cell binding and internalization [6]. It is estimated that the viral coat is comprised of 60 proteins arranged into an icosahedral structure with the capsid proteins in a molar ratio of 1 1:1:10 (VP1:VP2:VP3) [6]. The gene encodes the assembly-activating protein (AAP) in an alternate reading frame overlapping the gene. This nuclear protein is thought to provide a scaffolding function for capsid assembly [7]. While AAP is essential for nucleolar localization of VP proteins and capsid assembly in AAV2, the subnuclear localization of AAP varies among 11 other serotypes recently examined, and is nonessential in AAV4, AAV5, and AAV11 [8]. Although there is much more to the biology of wild-type AAV, much of which is not fully comprehended, this is not the form that is used to generate gene.