GMP Retrovirus Production Services

Standardized processes and partnerships with global providers facilitate standardized BOMs, meaning raw materials are on hand on Day 0.

Our integrated plasmid DNA center of excellence enables us to jump-start your viral vector programs as early as possible.

With proprietary HEK293 and 293T producer cell lines for adherent or suspension culture, we offer large-scale purification services based on our clients’ preference, material needs, timeline, and long-term development plan.

Our platform approach to vector manufacturing provides retroviral vector gene therapy developers an expedited, cost-effective, and predictive pathway to GMP manufacturing, relying on proven cell lines, extensive development and manufacturing experience, and templated documentation.

Analytical method development and testing capabilities with a range of pre-qualified platform assays, well-versed assay tech-transfer capabilities, and industry-leading assay development services.

Retroviruses are a family of viruses characterized by their ability to reverse transcribe their RNA genomes into DNA, which can then stably integrate into the host cell genome. Because of their ability to permanently modify the genetic makeup of a target cell, retroviruses attracted attention early on and became the first viral vectors to be used in gene therapy clinical trials. Importantly, retroviruses can only transduce dividing cells, whereas lentiviruses can transduce both dividing and non-dividing cells. Most retrovirus vectors are based on murine leukemia virus (MLV), a simple or gamma-retrovirus (as opposed to lentiviruses, which are more complex members of the retrovirus family). Retroviruses have a greater variety of stable producer cell lines available than do lentiviruses, due to their longer history of use, more simplistic genomes, and because some lentivirus accessory genes are toxic to mammalian cells.

Clinical-grade retroviral vector production involves many steps to ensure the quality and safety of the final product. Altogether, it can take 10-15 months to complete a GMP project. This timeline can be significantly shortened if a manufacturing process has already been developed and/or if an engineering run is not required.

The Retrovirus Manufacturing Process:

1. The first step of any campaign is the process development phase, in which various parameters involving the source plasmids, production/producer cell lines, and purification methods are optimized.
2. Following this step, procedures must be adapted to the larger scales required to generate the increased amounts of material required for clinical trials.
3. Next, an engineering run is often performed to confirm that the processes and procedures yield the expected amount of virus at the larger scale.
4. After the engineering run, a GMP run that fully complies with FDA and EMA guidelines is performed. This is the run that produces the material for clinical use. However, before this material can be used in patients, quality control testing must be conducted to confirm the final product’s identity and purity.
5. Finally, release testing must also be completed before the final product is deemed ready for use in patients. The release testing confirms sterility and stability of the final product.

The engineering run is an important part of any retrovirus manufacturing campaign as it allows for the detection of any unforeseen issues that could impact CGMP retrovirus production. The engineering run uses the exact same procedure as the GMP run but is not performed under full GMP conditions (i.e., not subject to QA oversight). This run allows for the confirmation that all of the campaign-specific processes will be successful and that the expected viral titer will be obtained. Material produced during the engineering run can be used for in vitro or in vivo testing (or toxicity studies) but cannot be used in patients.

Because viral vector titer is highly sensitive to the size of the viral genome, the resulting retroviral vector manufacturing yield will vary depending on the size of the desired insert. Please contact us for more information about what yield may be obtainable with your insert.

We primarily use a third-generation retrovirus packaging system, in which the retrovirus genome is distributed among three plasmids. This greatly reduces the likelihood of recombination events that could allow generation of replication-competent retrovirus. Over the long history of retrovirus clinical trials, it has demonstrated a predominantly safe track record, although some insertional mutagenesis events have occurred in a limited number of patients. However, the continued development of self-inactivating vectors and other measures taken to reduce risk have resulted in increasingly safe retroviral vectors.

Retroviruses have an insert capacity like lentiviruses. Depending on the specific virus and the source, the capacity is variously reported as ranging from 7 kb to 8 kb. However, as with lentiviruses, the efficiency of retrovirus production depends heavily on the size of the insert. It is important to note that the packaging capacity includes not only the gene of interest but also any other components (promoters and other regulatory elements, selection markers, etc.) that might be included in the construct.