Adenovirus (Adv) is double-stranded DNA
(dsDNA) virus, belong to the Adenoviridae family, adenovirus vector is derived from
Adv, have been frequently used for recombinant protein expression in mammalian
cells and for applications in gene therapy. Adenovirus are capable of infecting
a broader variety of cells, including those that have a comparatively slow rate
of cell division. When adenoviruses infect a host cell, their genetic material
(DNA) is not incorporated into the host’s genome and left free in the nucleus
in the form of an extrachromosomal gene segment, which is also known as an
episome. Their extrachromosomal location prevents germline gene transfer and
also eliminates the risk of cancer due to insertional mutagenesis.
During the
years adenovirus vectors have seen a multitude of improvements including
engineering of gutless vectors with deletions in the E1-4 genes to reduce the
vector toxicity and increase packaging capacity(~35 kb). The E1 gene products,
E1A and E1B, are involved in the replication of the virus. The E2 proteins
provide the machinery for viral DNA replication and facilitate transcription of
late genes. Most of the E3 proteins are involved in modulating the host’s immune response. The E4 gene products are
involved in the metabolism of virus messenger RNA (mRNA), promotion of viral
DNA replication and in shutting-off of host protein synthesis. Adenovirus
vector have commonly been subjected to several preclinical and clinical trials.
Engineering of packaging cell lines for adenovirus vector have significantly
facilitated virus production.
Adenovirus vector advantages
Easily manipulated in laboratory setting
High expression of transgene
Broad tropism, including DC
No risk of insertional mutagenesis
Many strains available
Replication-deficient strains used, limiting pathogenicity
Reference:
Viral Vector –based Therapeutic Cancer Vaccines. Cecilia Larocca, B.S. and Jeffrey Schlom, Ph.D. Cancer J. 2011 September ; 17(5): 359–371.
Viral Vector-Based Cancer Immunotherapy.
Lundstrom K. Viral Vector-Based Cancer Immunotherapy. Austin Immunol. 2016;
1(2): 1008.