Category: <span>Viral Vectors</span>

Adenoviral vectors (AAV’s) offer a promising new approach to vaccine development. They have the ability to be rapidly manipulated for bearing transgenic coding for specific antigenic proteins, efficiently infect a variety of mammalian cell types (including antigen-presenting cells) and induce a broad immune response against the target antigen in vaccine recipients. Furthermore, AAV’s offer an excellent safety profile, in that they can be engineered to be non-replicating in the vaccine recipient and they lack the molecular mechanism for integration into the host genome. AAV’s are highly amenable to scalable manufacturing processes such as the use of stirred tank bioreactors, high capacity filtration methods, and chromatographic purification procedures…

Biologics Production Viral Vectors

Despite 20 years of intensive research, the development of an effective vaccine to combat the worldwide AIDS pandemic remains an elusive goal. Currently, more than 40 million individuals are infected with human immunodeficiency virus (HIV) and there have been more than 25 million related deaths. Globally, the rate of new infections is alarming, with ten new infections occurring every minute. Ninety-five percent of these infections occur in the developing world. Several significant challenges face the development of an effective HIV vaccine…

Manufacturing Viral Vectors

The number of viral vectors designed for gene therapy applications in the cGMP pipeline is staggering. Similar in scope to the flurry of recombinant protein products of the 1980s and the monoclonal antibodies (MAbs) of the 1990s, viral vector-based products are surging from research labs and universities into contract manufacturing organizations (CMOs), ultimately destined for use in clinical trials. Unlike recombinant proteins and MAbs, both of which sometimes require grams of vialed final product to start Phase I studies, the amount of material required to move a viral vector-based product into clinical trials can be minute in comparison. Of all the viral vectors currently in clinical trials, more than 25% are based on adenovirus…

Cell & Gene Therapy Viral Vectors

The Lentiviral Vector Reference Working Group (LVRWG) was created at the conclusion of a meeting organized by The Williamsburg BioProcessing Foundation in June 2002, in conjunction with the American Society of Gene Therapy (ASGT) annual conference. The meeting participants were gathered to evaluate the need for developing reference material to ensure comparability of lentiviral and retroviral vectors, in a similar spirit to the Adenovirus Reference Material program that had just been completed. The concensus at the conclusion of this meeting was that the diversity in the lentiviral vector field, which includes vectors derived from different parental viruses and with various designs, does not allow for identification of a single reference material that would benefit more than a single or very few investigators…

Viral Reference Materials Viral Vectors

With the advent of the first gene therapy product to market, the industry faces the challenge of mass-producing high-purity viral particles and plasmids. The concept of manufacturing therapeutic genes rather than therapeutic proteins as marketable products is still in its infancy. Although manufacturers of biopharmaceuticals have decades of experience in the purification of proteins, virus and plasmid products pose unique challenges that cannot be addressed without some modifications to traditional, protein-based approaches…

Biologics Production Cell & Gene Therapy Viral Vectors

The Good Manufacturing Practices (GMPs) are becoming more and more familiar in biotechnology, and concepts such as quality assurance or validation are now part of the background of clinicians and researchers involved in clinical trials. A recent European Community directive (2001/20/CE) states that GMPs should also be applied to investigational medicinal products and not only to products on the market. Vector supernatant is a so-called Active Pharmaceutical Ingredient (API) and is subject to the same guidelines as traditional drugs produced by the pharmaceutical industry. This has a deep impact in the field of gene therapy because clinical trials are often run by small biotech companies or, at least in the first phases, by academic centers. The field is continuously developing and, according to the progress of the clinical studies, new processes are necessary to produce large-scale amounts of vector supernatant in a safe and reproducible way…

Manufacturing Viral Vectors

Gene therapy is a promising medical technology that has the ability to treat inherited diseases. However, efficient and economical large-scale production of vectors is necessary to meet the potential patient demand. Several approaches have been evaluated for the mass production of retroviral vectors, including fixed-bed bioreactors, suspension cultures, and microcarrier cultures. In this article, we report on the use of a Cytopilot fluidized-bed bioreactor for the production of retroviral vectors from the human packaging cell line TEFLYRD…

Cell & Gene Therapy Viral Vectors

Currently, the U.S. Food and Drug Administration (FDA) recommends DNA sequencing for the structural characterization of gene transfer viral vectors in investigational New Drug Applications (INDs). While FDA provides guidelines on what should be sequenced in regard to these vectors, it provides little insight — beyond GLP/GMP (GxP) guidelines — into how the finalized sequence data should be obtained. There is presently no provision for determining which sequencing methodology (or methodologies) is most appropriate for obtaining a completed sequence characterization for each of the different vector classes, and there is no standard that outlines what DNA sequencing-specific criteria the data and data collection processes should meet in order to guarantee that the sequence is 99.99% accurate…

Nucleic Acids Research Uncategorized Viral Vectors

The modern era of interest in gene transfer as a methodology for treating disease began around 1985 with the first use and publication of mouse-based retroviruses that could transduce human cells. In fact, the use of gene transfer as a clinically useful method is probably older than any other therapy commonly used today — it forms the basis for the vaccinia vaccination against smallpox, popularized in Western medicine by Jenner. Another antecedent is phage therapy for bacterial infection, which was largely but not completely superseded by antibiotics (although it may make a comeback in this era of drug-resistant pathogenic bacterial strains.) Other examples include the other live viral vaccines: measles/mumps/rubella, polio, varicella, tuberculosis, influenza, the use of bacillus Calmette-Guérin (BCG) as a therapeutic for bladder cancer bone marrow transplants, and even the use of maggots to clean wounds…

Cell & Gene Therapy Viral Vectors

The Adenovirus Reference Material Working Group (ARMWG) oversaw development of an adenovirus reference material (ARM) with the intent to provide a way to standardize assay measurements from different laboratories. The ARM, which was manufactured in stages by various organizations including Canji (San Diego, CA) and Introgen Therapeutics (Houston, TX), is available from American Type Culture Collection (Manassas, VA). Upon completion of its manufacture, the characterization phase primarily defined viral particle concentration as well as infectious titer for this product. However, many other concurrent characterization studies were conducted including an assessment of vector purity (e.g., host cell DNA, host cell protein, reversed-phase HPLC), a short-term field use and shipping stability study, and a long-term stability study. Also included in these studies was a coordinated effort to determine the complete DNA sequence of the ARM vector genome…

Nucleic Acids Viral Reference Materials Viral Vectors