Overcoming the Challenges of Lentiviral Vector Production

Lentiviral vectors are versatile gene delivery tools, capable of transducing a wide range of cell types. However, producing large volumes of high-quality lentiviruses can present several challenges. Global biotech company GenScript recently launched its Research Lentiviral Vector Packaging Service, which exploits the company’s proprietary lentiviral production platform to ensure consistent production of intact, functional viruses.

To learn more about the service and how it addresses some of the difficulties associated with lentiviral production, Technology Networks spoke to GenScript’s Koh Meng Yong, PhD. In this interview, Dr. Meng Yong also discusses the advantages of using lentiviral vectors and some of the applications they are enabling.

Anna MacDonald (AM): Can you explain what a lentivirus is and highlight some of their applications?

Koh Meng Yong (KMY): Lentiviruses are RNA viruses typically 80-120 nm in diameter and are characterized by a long incubation period within the infected host cells before disease manifestation. Lentiviruses belong to the family of retroviruses with the ability to integrate their viral genome into infected host cells. To make them safe for use in research, scientists have generated recombinant lentiviruses that retain the ability to integrate into the host genome without causing disease. This makes them ideal vectors in cell engineering applications where the intent is to create a modified cell that stably expresses or lacks a specific gene.

AM: How are lentiviruses being used to help COVID-19 drug discovery efforts?

KMY: Lentiviruses are being used to deliver individual viral proteins into human cells to understand how they interact with the human protein. By studying these interactions, it is hopeful that researchers can identify existing drugs that can disrupt these interactions and potentially be used as a disease treatment for patients infected by the virus. 

AM: What are the main advantages of using lentiviral vectors over other viral vectors?

KMY: Lentiviruses work by first infecting a cell and releasing their RNA material into the host cell cytoplasm. There the RNA gets converted into DNA and ultimately integrates into the host cell genome, causing long-term genetic modification to the host cell. This makes them highly efficient in engineering a cell permanently, allowing for stable expression of the viral genome. Secondly, the amount viral genome carried is large, making it a desirable vehicle for delivering large transgenes into cells. The envelope protein can be further modified to allow the viruses to infect a broad range of tissue types and lentiviruses possess the ability to infect dividing and non-dividing cells. Lastly, they are low in immunogenic ability, ensuring that the host cell immune system does not mount an immune response to the virus.

AM: How are lentiviral vectors produced? What are the main challenges of this process?

KMY: First, you take your packaging plasmids that encode for the viral particle and your plasmid vector bearing transgene to be packaged into the virus and co-transfect them into a packaging cell line grown in culture medium. A few days after co-transfection, the virus particles released into the culture medium can be harvested and subject to downstream processing such as purification and concentration. There are many variables that affect the quantity and quality of viral preps during the preparation process. These include transfection efficacy of the packaging cell lines, the production capacity of the cell line and the purification and concentration of the viral particles.

AM: Can you tell us more about GenScript's Research Lentiviral Vector Packaging Service and how it addresses these challenges?

KMY: At GenScript, we have developed a unique production protocol optimized to produce highly purified virus at maximum yield. These optimal conditions apply to every step of the virus production protocol and include: An optimized transfection protocol for high scalability and virus yield and a serum free system that produces lentivirus free of animal growth factors. This is particularly important when working with primary cells that may be more responsive to these growth factor contaminations. We also have a careful and thorough virus purification and concentration protocol that ensures that viral particles remain intact and functional. Furthermore, we have multiple methods of measuring titer and quality control to ensure viral preps are free of mycoplasma or bacterial contamination. All this translates to higher quality, intact and functional viral preps that help make our clients’ next cell engineering project a success.

Koh Meng Yong was speaking to Anna MacDonald, Science Writer for Technology Networks. Dr Meng Yong is global product manager, Assay Cell Lines and Lentivirus Packaging Services for GenScript.