The risk of insertional mutagenesis is reduced when nonintegrative viral vectors are used. These viral vectors are commonly used in suicide therapy or to initiate cascade processes.
Nonintegrative viral vectors do not have the ability to integrate into the host cell’s genome thus, reducing the risk of insertional mutagenesis.
Adenovirus is the most common “vehicles” used for gene transfer in research and clinical applications especially for cancer. They could be used as viral vectors or their oncolytic versions.
AVs have two different approaches :
AVs can transduce wide range of tissues including dividing and non-dividing cells. Its genome is comprised of two groups: trans-genes (useful for AVs) and cis-genes.
HSVs is an enveloped, neurotropic virus that can carry large-sized inserts, long-term episomal expression in the central nervous system, and other. The most used HSV for gene therapy are HSV-1 (serotype 1) and HSV-2 (serotype 2).
HSV-1 for gene therapy are designed to reactivate from latency stage and to remove essential genes for genetic transference and expression of the therapeutic gene.
Vaccinia virus or VV is a large, complex, and envelope poxvirus that was clinically used for smallpox vaccine. VVs can carry until 25kb foreign DNA without the need for viral deletions. These vectors permit infection in primary cultures, wide range of cell lines, cytoplasmic replication, and more.
Diverse promoters are used (natural or synthetic) to regulate the activity levels of VV-derived vectors.