Jun 14, 2018
Human ingenuity has turned the sinister HIV-1 virus into a convenient laboratory tool for gene delivery as lentiviral vector. After multiple rounds of engineering, the 3rd generation of lenti viral system has diminished the possibility for the lab-made virus to replicate and to impose health risk to laboratory staff. While it is important that we treat all laboratory tools with respect, there is no reason to shy away from lentivirus. If you know how to handle routine cell culture, you know how to handle lentivirus. With safety measures built into the vector and BSL2 laboratory precautions, lentivirus has become a powerful tool shaping the landscape of genetic research and medicine today.
Built-in Safety Measures
The primary concern for lentivirus is that anomalous replication might occur. This concern was specifically addressed in the 3rd generation lentiviral vectors by several safety features to eliminate recombinant replication.
- Divide and Conquer: The genome for essential viral proteins for replication was split into four separate plasmids. In this way, the genes necessary for envelope proteins and replication are not present in the viral capsid during development or in their finished form.
- Separate the key and the lock: To further ensure the viral genome is not present in the pseudovirus, Ψ (Psi) packaging sequence is only present on the plasmid carrying the gene of interest. In effect, the genetic components needed to construct new viruses don’t get packaged in the newly formed virion.
- Minimal virus: Researchers also removed unnecessary HIV-1 genes leaving only gag, pol, and rev.
But, it doesn’t stop there - to learn more about all of OriGene’s built-in lentiviral biosafety considerations click here.
Physical Safety Precautions for handling Lentivirus
The built-in safety measures discussed above prevent lentivirus from replicating. However, it is still a virus capable of single- round infection of mammalian cells. Using lab coats, gloves, a biosafety cabinet, and decontamination of waste are fundamental safety precautions when working with lentivirus. Beyond the typical BSL2 precautions it is necessary to consider the genetic payload as a determinant of the safety measures required. For instance, a human structural protein would likely be less dangerous than a human growth factor. But what does that mean regarding practical tools and procedures?
- Open virus containing microtubes in the biosafety cabinet.
- Best to avoid using sharps or implement additional care to avoid autoinoculation.
- Precaution should be taken when the gene to be introduced is oncogenic or otherwise dangerous to humans.
- When the gene has inherent risk to humans, researchers should wear long gloves to cover the wrists and a face mask to avoid breathing aspirated virus. (This should always be the case but the face mask is only important if there is a chance of large volume spills)
- Tissue culture dishes should be transported from the biosafety cabinet to the incubator in a marked secondary container to avoid the possibility of spills.
- Once in the incubator, the secondary container’s lid can be cracked to allow gas exchange (secondary containers are most often tupperware).
A discussion of special considerations regarding oncogenes in lentiviruses was written by the Recombinant DNA Advisory Committee (RAC). This resource is a helpful place to start when thinking about the implications of the gene of interest. For full guidelines on the appropriate handling of lentiviral vectors visit The NIH Guidelines for research involving recombinant or synthetic nucleic acid molecules and OSHU’s Lentiviral Biosafety Manual.
Lentivirus is a Powerful Tool for Gene Delivery
There are multiple reasons for scientists to choose lentivirus over chemical transfection and electroporation.
- Broad cell spectrum
- Gentle delivery with low level of cytotoxicity
- High delivery efficiency (in most commonly used cell lines)
- Prolonged protein expression
Lenti is in the spot light(spotlight?) with the advance in CAR-T therapy
Utilization of Lentiviral vectors has driven the advancement of genetic medicine. This year represents the first ever implementation of lentivirus in the FDA approved CAR-T therapy Kymriah ( for cancer treatment.)/ to treat acute lymphoblastic Leukemia (ALL). CAR-T is a type of genetic therapy in which white blood cells are removed from the body, genetically modified using lentivirus, and replaced to fight certain types of cancer. Even more exciting is that 83% of patients treated with Kymriah entered remission after three months during the clinical trial. After this monumental success, an explosion of demand for lentiviral vectors occurred. With nearly all clones of human and mouse genome in plasmids and with our lentiviral production expertise, OriGene is poised to answer the rising demand.
If you are on the fence about using lentiviruses, search OriGene’s site to find your gene of interest or request a quote for a custom vector.