Knobless Adenovirus Vector Construction Service
Recombinant adenoviral (Ad) vectors are being used as gene delivery vectors in a variety of gene therapy strategies. However, the lack of specific targeting of Ad vectors in vivo may inhibit the efficient transduction into cells of the therapeutic gene. This has led to the need for high vector dose transduction, increasing the risk of unwanted side effects during gene therapy. Therefore, if a particular gene is only transferred to the desired target cells, the Ad vector may be greatly improved. Creative Biolabs is doing this work to improve the effectiveness of gene therapy by modifying the Ad capsid.
Introduction of Knobless Ad Vector
Ad vector systems for gene therapy can be greatly improved by targeting specific cell types of vectors. It has been previously determined that the Hi ring of the fibrous nodal domain is the preferred site for targeting ligand binding. The structural properties of the Hi ring allow the insertion of multiple ligands, including large polypeptide molecules. Previous studies have determined that the structure of Ad fibrin imposes strict size restrictions on ligands bound to its carboxyl end, thus limiting the range of potential candidate ligands and making them short peptides. Therefore, in order to eliminate this restriction, it is necessary to completely eliminate the tendency of natural adenovirus and introduce a new binding affinity into the capsid of the virus. Current studies have shown that these requirements can be met by deleting the entire knob domain of adenovirus fibrin and replacing it with two distinct parts, providing trimerization of knobless fibers and specific binding with target cells, respectively. Hence, these knobless fibers are prototype substrates for multi-purpose addition of targeting ligands to produce truly targeted adenoviruses.
Figure 1. Selective retargeting of Ad vectors. (Mathis, 2005)
Knobless Ad Vector Construction
The way we develop knobless Ad vector is to delete the entire fiber knob and replace it with two different protein parts, which provide the trimerization function for the knobless fiber and specifically bind to target cells. Scientists have constructed an Ad vector carrying knobless fibers containing the alpha-helix trimerization domain of glycoprotein encapsulated by Moloney murine leukemia virus (MoMuLV). Two simulated targeting ligands, Myc-epitope and 6*His-tag, are linked by the flexible conjugated peptide. The results showed that targeted knobless fiber molecules were correctly expressed and introduced into the nucleus of adenovirus packaging cells, where they were incorporated into the adenovirus capsid as functional trimers. Both ligands are exposed to the surface of viral particles and can be used to specifically bind to their target molecules. In addition, knobless fibers mediate gene delivery to cells that display coupled ligand receptors.
The advantages of our non-binding adenoviral vector include:
- Increased range of potential ligand candidates and short peptides;
- As a multi-functional prototype substrate for adding targeted ligands to produce truly targeted adenoviruses;
- Improving the targeting of Ad vectors and the efficacy of adenovirus-based gene therapy.
Figure 2. Genetic retargeting of recombinant knobless Ad vector. (Magnusson, 2002)
Services
Creative Biolabs has more than 10 years of experience in viral vector projects, providing various vector design and construction services in gene therapy. Regardless of the stage, scope or scale of your project, we can provide you with customized solutions to meet your manufacturing needs. In terms of the construction of knobless Ad vector, we can carry out comprehensive construction services, including but not limited to:
- Customized knobless Ad vector construction, packaging and extension services;
- Cloning and construction of more difficult genes, including Ads with cytotoxic effects;
- Full package of Quality control and identification.
If you are interested in our Ad vector construction services, please feel free to contact us.
References
- Mathis, J.M.; et al. (2005). Oncolytic adenoviruses-selective retargeting to tumor cells. Oncogene. 24(52): 7775.
- Magnusson, M.K.; et al. (2002). Genetic retargeting of adenovirus vectors: functionality of targeting ligands and their influence on virus viability. The Journal of Gene Medicine. 4(4): 356-370.
