How are viral vectors used in gene therapy?
Certain viruses are often used as vectors because they can deliver the new gene by infecting the cell. The viruses are modified so they can ‘t cause disease when used in people. Some types of virus , such as retroviruses, integrate their genetic material (including the new gene ) into a chromosome in the human cell.
What are the three most common vectors used in gene therapy?
Adenovirus (Ad) vectors, adeno -associated virus (AAV) vectors, retrovirus vectors, and herpesvirus vectors are the few viral vectors that have advanced to clinical trials aimed at developing gene therapy products for their safety and biological function.
What are the advantages of using viral vectors for gene therapy?
Benefits and advantages of using the Adeno-Associated Virus as the vector in gene therapy trials include integration into host genome, no viral genes, able to transduce cells not actively dividing, and they are non-inflammatory and non-pathogenic.
What are the types of viral vectors?
The most commonly used types of vectors at present are lentiviral vectors (usually derived from HIV), adeno -associated virus vectors and adenoviral vectors .
What are the two types of gene therapy?
There are two types of gene therapy treatment: Somatic cell gene therapy and germline therapy. Somatic cell gene therapy involves obtaining blood cells from a person with a genetic disease and then introducing a normal gene into the defective cell (Coutts, 1998).
Are viral vectors safe?
Safety : Although viral vectors are occasionally created from pathogenic viruses , they are modified in such a way as to minimize the risk of handling them. This usually involves the deletion of a part of the viral genome critical for viral replication.
What are some examples of gene therapy?
Human gene therapy has been attempted on somatic (body) cells for diseases such as cystic fibrosis, adenosine deaminase deficiency, familial hypercholesterolemia, cancer, and severe combined immunodeficiency (SCID) syndrome.
What are the applications of gene therapy?
Gene therapy can deliver to target cells genes that code for the missing biological factor. Cancer, infectious diseases, cardiac disease, neurological disorders and some inherited conditions are among the areas into which gene therapy research is being carried out.
Which viruses are used for gene therapy?
Several types of viruses, including retrovirus , adenovirus , adeno-associated virus ( AAV ), and herpes simplex virus , have been modified in the laboratory for use in gene therapy applications. Because these vector systems have unique advantages and limitations, each has applications for which it is best suited.
How are viral vectors created?
Cells are transfected with plasmids to generate the viral vector , which is harvested. AAV viral particles accumulate in the cytoplasm and the media, so total yield can be enhanced by lysing the cells. Harvested vector is then concentrated, purified, titrated, characterized, and stored for later ex vivo or in vivo used.
What are the challenges of gene therapy?
Difficulties include delivery of the vector to the cell, lack of persistent gene ex- pression in targeted cells, and immune responses to viral gene products, transgenes, or cells targeted by the vectors.
What can you say about the bioethical issues of gene therapy?
Germline gene therapy poses risks not only to patients but also to future generations. Germline gene therapy raises difficult ethical questions related to tampering with human nature, enhancing human traits, parental control over children, discrimination, social justice and eugenics.
What is a replicating viral vector?
Viral vectors for which both replicating and non- replicating forms are available include adenoviruses and poxviruses. Vectors designed primarily as replication -defective include adeno-associated virus , alphavirus, and herpesvirus, while replicating vectors include measles virus and vesicular stomatitis virus .
What are the advantages and disadvantages of using viral vectors?
|In vivo administration||The pre-existing immunity against adenoviruses in individuals may result in low levels of transgene delivery and expression|
|Extensive clinical experience||Vectors are immunogenic since the virus capsid and remaining viral proteins cause inflammation|
What are the types of non viral vectors?
The non-viral vectors are Naked DNA , particle based and chemical based. They are administered by direct administration ( plasmid DNA/ Naked DNA )/ chemical /physical.