Hybridoma cell lines are highly unpredictable and often, an unreliable source of important antibodies of national security interest. There is an urgent need to convert antibody production from these cell lines into robust, recombinant platforms that can reliably produce large quantities of antibody on demand, and abandon methods based on murine ascites production. This work describes the use of lentiviral vectors, Chinese hamster ovary (CHO)-K1 cells, and high-density perfusion cultures for antibody production. Cell line development was rapid, high insertion copy numbers were achievable, and the heavy/light chain ratios could be rapidly optimized. The mammalian cells provided an appropriate environment for IgG folding and obviated the difficult purification steps such as removal of endotoxins, refolding, or dealing with abnormal post-synthetic modifications common to other production systems. We found that even in the absence of an optimized cell line, in high-density cultures, routine productivities in the 1–5 g/L range were achieved. As expected, productivity was independent of the performance of the original hybridomas. We conclude that the lentiviral vector system can achieve high copy numbers of immunoglobulin genes with optimized heavy and light chain ratios to appropriately assemble and secrete the immunoglobulins, achieving high productivity. This observation suggests that substantial advances can be made by selecting and optimizing the cell line used for immunoglobulin production. The lentiviral vector-based method of antibody production offers substantial improvements over traditional murine ascites-based antibody production in terms of reliability, productivity, and cumulative cost—if the antibody need exceeds 1–3 grams within the shelf life of the product…
Tag: <span>lentiviral vectors</span>
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…
The use of virus-based vectors for gene transfer has become an important delivery method for both in vitro applications and in vivo experimental clinical therapies. In small-scale experimental applications, most vectors can easily be concentrated and purified by simple methods (for example, ultracentrifugation.) However, it is challenging to scale up centrifugation-based vector purification methods for the large-scale production required for clinical use. In particular, when considering production of vector for human use, additional steps such as final sterilization by filtration must be taken to ensure the purity and safety of the vector preparation. Because the vector aggregates when pelleted by centrifugation, sterile filtration will eliminate vector particles from the solution. An efficient vector purification process that maintains vector potency is an important step in vector production for gene therapy…
The first HIV-based lentiviral vector to be used in humans, VRX496, is currently being tested in Phase I clinical trials (initiated in January 2003). With each new therapeutic comes the need to establish quality control (QC) testing designed specifically for that product. The QC testing for VRX496 was developed in accordance with the Code of Federal Regulations (CFR) 21 for pharmaceutical and bulk chemical GMPs, Points to Consider in the Characterization of Cell Lines Used to Produce Biologicals (1993) from the Center for Biologics Evaluation and Research (CBER) at FDA, and the United States Pharmacopeia (USP) 1046 for Cell and Gene Therapy Products. This report describes the QC testing of lot VRX496V02-009 of our clinical grade vector, which is being used in an ongoing clinical trial evaluating the first lentiviral gene therapy vector in humans. All assays are performed according to established standard operating procedures (SOPs) and in accordance with the principles of cGMP regulations…