A critical step in the production of vaccines and viral seed stocks lies in the generation of appropriate research materials and carefully selected expression systems, developed to ensure productivity and efficiency throughout the downstream manufacturing process. The quality of these research tools directly impacts the quality of the clinical lots produced.
At Advent, we have extensive experience in the generation of high quality research materials such as cell lines, pre-GMP virus seed stocks and research batches. This includes the development of different mammalian expression systems, starting from the gene of interest.
Furthermore, we have developed strong and consolidated expertise in the adenoviral platform, both from human and non-human sources, used for the generation of prophylactic and therapeutic vaccines for Phase I and II clinical studies.
Adenovirus vector-based vaccines are engineered to be replication deficient, and can be manufactured in well-established cell lines containing the adenoviral E1 gene.
To support the adenoviral platform, our cell culture team is focused on maximizing cell line productivity. In addition, our team works on adapting the cells to grow in defined media to meet the downstream processing requirements.
Pre-GMP virus seed stocks, which will be used as starting material for the clinical manufacturing of vaccine lots, are generated in our dedicated laboratory in adherent and/or suspension customer-specific cell lines.
Our flexibility enables us to offer our clients the opportunity to outsource the entire development process of their expression systems. Alternately, we can start from any intermediate step, depending on the specific needs of our clients.
Our capabilities include:
- Transfection of specifically designed plasmids into mammalian cells
Transfection is a process that allows us to introduce DNA plasmids into cells. Our method utilizes liposome transfection. In general, adherent cells are seeded and, once the appropriate confluence is reached, cells are transfected with a mixture of DNA and transfection reagents. After the incubation period, the cells are harvested and used for the amplification of the gene of interest.
- Isolation and amplification of the gene of interest
Lysates from transfection are collected and used to generate amplification passages.
During the first amplification passage, the cells are infected with the lysate coming from the transfection. When the cells reach full cytopathic effect, they are collected and used for further amplification passages. Once a detectable virus quantity has been produced, cells are infected at a defined multiplicity of infection and single clones are isolated by using different techniques (for example plaque picking or limiting dilution). The clone identified as best in terms of productivity and expression is subjected to the minimum round of amplifications to reach the target size of pre-GMP virus seed stock, enough to support Process Development studies and the manufacturing of toxicology and clinical lots.
- Optimization of cell-vector systems
The infection parameters, such as cell density, time and so on, are optimized on the basis of our strong experience with the aim to obtain a final product of high quality that meets the client needs.
- Generation and characterization of the pre-GMP virus seed stock
The pre-GMP virus seed stock is subjected to an extensive characterization. The suitability of pre-GMP virus seed stock generated by Advent, for further use in the Clinical Lot production, is verified through the study of the genetic stability of the vector: the virus is subjected to several amplification cycles and tested in order to confirm that no genetic changes happen during the production process.