2.3. Lentiviral and AAV Vectors

Lentiviral and AAV Vectors: ○ Deliver therapeutic genes into stem cells for long-term expression

Lentiviral and Adeno-Associated Virus (AAV) vectors are tools used to carry and deliver therapeutic genes directly into stem cells. This is important because when a gene is delivered effectively, it can lead to long-term expression of that gene. In simpler terms, these vectors act like delivery trucks that transport the necessary instructions (genes) into stem cells to help them perform specific tasks, like repairing tissues or correcting genetic disorders.

Imagine you are sending a package to a friend. The package contains instructions on how to build a piece of furniture. Lentiviral and AAV vectors are like the delivery service that ensures your package reaches your friend's house. Once the package is there, your friend can follow the instructions to create the furniture, just as stem cells can use the delivered genes to produce needed proteins or other components for healing.

Lentiviral vectors are derived from HIV and can integrate into the host cell's genome, allowing for stable gene expression.

Lentiviral vectors are engineered from a virus that is known as HIV (Human Immunodeficiency Virus). Despite its reputation, when used in this way, the virus is modified so it cannot cause disease. One of the main advantages of lentiviral vectors is their ability to integrate into the DNA of the host cell. This means that once the gene has been delivered, it can be passed on to daughter cells when the stem cell divides, resulting in stable, long-term expression of the gene.

Think of Lentiviral vectors as library books that are placed on a shelf in a public library. Once a book is on the shelf, it remains there and can be checked out by many different readers in the future. Similarly, when a lentiviral vector integrates into the DNA of a stem cell, it’s like adding important information to the library of that cell’s DNA, which can be utilized by future generations of cells.

AAV vectors are non-pathogenic and can also deliver genes without integrating into the host genome, providing transient expression.

AAV vectors differ from lentiviral vectors in that they do not typically integrate into the host cell's DNA. Instead, they deliver genes that typically provide a temporary effect. This is often useful in situations where transient gene expression is sufficient, such as in temporary studies or certain therapies. The safety profile of AAV vectors is also particularly favorable as they are derived from a virus that does not cause diseases in humans.

Consider AAV vectors like flash drives that you borrow from a friend. When you plug the flash drive into your computer, you can access the files on it for a short period, but the files do not permanently change anything on your computer. Similarly, AAV vectors provide beneficial information to the cell but do not alter the underlying programming of the cell’s DNA, leading to temporary results.

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