Lentiviral vector in gene therapy
Lentiviral vectors in gene therapy is a method by which genes can be inserted, modified, or deleted in organisms using lentiviruses.
Lentiviruses are a family of
To understand the capabilities of a lentiviral
There are multiple steps involved in the infection and replication of a lentivirus in a host cell. In the first step the virus uses its surface glycoproteins for attachment to the outer surface of a cell. More specifically, lentiviruses attach to the
Two methods of gene therapy using lentiviruses have been proposed. In the ex vivo methodology, cells are extracted from a patient and then cultured. A lentiviral vector carrying therapeutic transgenes are then introduced to the culture to infect them. The now modified cells continue to be cultured until they can be infused into the patient. In vivo gene therapy is the sample injection of viral vectors containing transgenes into the patient.[5]
Designing a lentivirus vector
Lentiviruses are modified to act as a
Some experimental applications of lentiviral vectors
HIV-derived lentiviral vectors have been widely developed for their ability to target specific genes through the coactivator PSIP1.[9] This target specificity allows for the development of lentiviral gene vectors that do not carry the risk of randomly inserting themselves into normally functioning genes. As HIV is pathogenic, it must be genetically modified to remove its disease-causing properties and its ability to replicate itself. This can be achieved by deleting viral genes that are unnecessary for transduction of therapeutic transgenes. It has been proposed that by targeting the "gag" and "env" domains, enough of the HIV-1 genome can be deleted without losing its effectiveness in gene therapy while minimizing viral genes integrated into the patient.[10] Genes may also be replaced rather than disrupted as another method to reduce the risks associated with the use of HIV-1.[7]
Other lentiviruses such as Feline immunodeficiency virus[11] and Equine infectious anemia virus[12] have been developed for use in gene therapy and are of interest due to the inability to cause serious disease in human hosts. Equine infectious anemia virus in particular has been shown to perform somewhat better than HIV-1 in hematopoietic stem cells[13]
Insertional mutagenesis
Historically, lentiviral vectors included strong viral promoters which had a side effect of insertional mutagenesis, nuclear DNA mutations that affect the function of a gene.[14] These strong viral promotors were shown to be the main cause of cancer formation.[14] As a result, viral promotors have been replaced by cellular promotors and regulatory sequences.[14]
Contrast with other viral vectors
As mentioned, lentiviruses have the unique ability to infect non-dividing cells. Beyond that, there are several other properties that distinguish lentiviral vectors from other viral vectors. Such properties are important to consider when determining whether lentiviruses are appropriate for a given treatment.
Gammaretroviruses
Gammaretroviruses are retroviruses like lentiviruses. Murine leukemia viruses (MLVs) were among the first to be investigated for their use in gene therapy. However, recent research has favored lentiviruses for their ability to integrate into non-dividing cells. More practically, gammaretroviruses have an affinity for integrating themselves near oncogene promoters, bringing forward an adverse risk of tumors.[15] MLVs may be replication competent, meaning they can replicate in the host cell. These replication-competent viruses offer stable gene transfer and tumor and tissue specific targeting.[16]
Adenoviruses
In gene therapy,
Applications
Severe combined immunodeficiency disease
The ADA deficient variant of severe combined immunodeficiency (SCID) was treated highly successfully in a multi-year study reported in 2021. Over 95% of treated patients continued to be event free after 36 months, and 100% of patients survived this normally lethal disease. A self-inactivating lentiviral vector, EFS-ADA LV, was used to insert a functional ADA gene in autologous CD34+ hematopoietic stem and progenitor cells (HSPCs).[21]
Vascular transplants
In a study designed to enhance the outcomes of vascular transplant through vascular endothelial cell gene therapy, the third generation of Lentivirus showed to be effective in the delivery of genes to moderate venous grafts and transplants in procedures like coronary artery bypass. Because the virus has been adapted to lose most of its genome, the virus becomes safer and more effective in transplanting the required genes into the host cell. A drawback to this therapy is explained in the study that long-term gene expression may require the use of promoters and can aid in a greater trans-gene expression. The researchers accomplished this by the addition of self-inactivating plasmids and creating a more universal tropism by pseudotyping a vesicular stomatitis virus glycoprotein.[22]
Chronic granulomatous disease
In chronic granulomatous disease (CGD), immune functioning is deficient as a result of the mutations in components of the nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) enzyme in phagocyte cells, which catalyzes the production of superoxide free radicals. If this enzyme becomes deficient, the phagocytes can't kill effectively the engulfed bacteria, so granulomas can be formed. Study performed in mice emphasizes the use of lineage-specific lentiviral vectors to express a normal version of one of the mutant CGD proteins, allowing white blood cells to now make a functional version of the NADPH oxidase. Scientists developed this strain of lentivirus by transinfecting 293T cells with pseudotyped virus with the vesicular stomatitis G protein. The viral vector's responsibility was to increase the production of a functional NADPH oxidase gene in these phagocytic cells. They did this to create an affinity for myeloid cells.[23]
Prostate cancer
With prostate cancer, the lentivirus is transformed by being bound to
Haemophilia A
Haemophilia A has also been studied in gene therapy with a lentiviral vector in mice. The vector targets the haematopoietic cells in order to increase the amount of factor VIII, which is affected in haemophilia A. But this continues to be a subject of study as the lentivirus vector was not completely successful in achieving this goal. They did this by trans-infecting the virus in a 293T cell, creating a virus known as 2bF8 expressing generation of viral vectors.[25]
Rheumatoid arthritis
Studies have also found that injection of a lentiviral vector with
Diabetes mellitus
Like many of the in utero studies, the lentiviral vector gene therapy for diabetes mellitus is more effective in utero as the stem cells that become affected by the gene therapy create new cells with the new gene created by the actual viral intervention. The vector targets the cells within the pancreas to add insulin secreting genes to help control diabetes mellitus. Vectors were cloned using a cytomegalovirus promoter and then co-transinfected in the 293T cell.[27]
Neurological disease
As mature neurons do not divide, lentiviruses are ideal for division independent gene therapy. Studies of lentiviral gene therapy have been conducted on patients with advanced Parkinson's disease[28] and aging-related atrophy of neurons in primates.[29]
See also
References
- PMID 29654266.
- S2CID 25410405.
- ^ "Hear Luigi Naldini, MD, PhD, on the Giants of Gene Therapy Podcast | ASGCT - American Society of Gene & Cell Therapy". asgct.org. Retrieved 2023-10-10.
- S2CID 18997464.
- ^ PMID 33558455.
- PMID 15140964.
- ^ PMID 10753827.
- ^ "What are lentiviral vectors?".
- PMID 20195265.
- PMID 34103612.
- PMID 11893454.
- PMID 22716662.
- S2CID 22110597.
- ^ PMID 34452394.
- S2CID 235243645.
- PMID 16809312.
- PMID 16160140.
- S2CID 7340856.
- PMID 27105067.
- PMID 20808291.
- PMID 33974366.
- PMID 12818564.
- PMID 21544095.
- PMID 19373278.
- PMID 17269937.
- S2CID 21327455.
- PMID 16171885.
- S2CID 4993549.
- PMID 19013154.
Further reading
- Buchschacher GL, Wong-Staal F (April 2000). "Development of lentiviral vectors for gene therapy for human diseases". Blood. 95 (8): 2499–504. PMID 10753827.
- Escors D, Breckpot K (April 2010). "Lentiviral vectors in gene therapy: their current status and future potential". Arch. Immunol. Ther. Exp. (Warsz.). 58 (2): 107–19. PMID 20143172.
- Stein S, Ott MG, Schultze-Strasser S, Jauch A, Burwinkel B, Kinner A, Schmidt M, Krämer A, Schwäble J, Glimm H, Koehl U, Preiss C, Ball C, Martin H, Göhring G, Schwarzwaelder K, Hofmann WK, Karakaya K, Tchatchou S, Yang R, Reinecke P, Kühlcke K, Schlegelberger B, Thrasher AJ, Hoelzer D, Seger R, von Kalle C, Grez M (February 2010). "Genomic instability and myelodysplasia with monosomy 7 consequent to EVI1 activation after gene therapy for chronic granulomatous disease" (PDF). Nat. Med. 16 (2): 198–204. S2CID 21824897.
- Persons DA (May 2010). "Lentiviral vector gene therapy: effective and safe?". Mol. Ther. 18 (5): 861–2. PMID 20436489.