Chapter 18
Surface Modification of Adenovirus Vector to Improve
Immunogenicity and Tropism
Yasmine Gabal and Joshua D. Ramsey
Abstract
Although adenovirus is a popular vector for delivering genes, there are several drawbacks that limit its
effectiveness, including tropism and both the innate and adaptive immune responses. One approach that
has been used to ameliorate these drawbacks is PEGylation of the virus with subsequent modification to add
functional moieties for the purpose of cell targeting or enhancing infection. Here, we describe a general
approach for PEGylating adenovirus and conjugating cell-penetrating peptides to the surface of the virus to
impart the ability to transduce CAR-negative cells.
Key words Gene delivery, Gene vector, Adenovirus, Polyethylene glycol, PEGylation, Cellpenetrating peptides
1 Introduction
Adenovirus (Ad) is one of the most widely used gene delivery
vectors in gene therapy clinical trials [1] and has been proposed as
a vector capable of delivering DNA vaccines [2]. Most people,
however, possess neutralizing antibodies that inactivate the virus
[3]. In addition, systemic administration of high doses of Ad triggers an inflammatory immune response resulting in rapid clearance
of vector DNA from transduced tissues [4, 5]. Further, Ad relies on
interaction of the virus fiber and knob with the coxsackieadenovirus receptor (CAR) to initiate cellular attachment and ultimately infection. This reliance on the virus receptor limits the
ability of Ad to deliver genes to CAR-negative cells such cancer
cells, endothelial cells, epithelial cells, and smooth muscle cells
[6, 7].
For these reasons there is considerable interest in modifying
adenovirus to overcome these drawbacks. Approaches are typically
classified as either genetic or chemical modification of the virus. For
example, a common genetic approach to reduce immunogenicity is
to genetically replace Ad-5 (i.e., serotype 5) viral proteins, such as
Blaine A. Pfeifer and Andrew Hill (eds.), Vaccine Delivery Technology: Methods and Protocols, Methods in Molecular Biology,
vol. 2183, https://doi.org/10.1007/978-1-0716-0795-4_18, © Springer Science+Business Media, LLC, part of Springer Nature 2021
357
Surface Modification of Adenovirus Vector to Improve
Immunogenicity and Tropism
Yasmine Gabal and Joshua D. Ramsey
Abstract
Although adenovirus is a popular vector for delivering genes, there are several drawbacks that limit its
effectiveness, including tropism and both the innate and adaptive immune responses. One approach that
has been used to ameliorate these drawbacks is PEGylation of the virus with subsequent modification to add
functional moieties for the purpose of cell targeting or enhancing infection. Here, we describe a general
approach for PEGylating adenovirus and conjugating cell-penetrating peptides to the surface of the virus to
impart the ability to transduce CAR-negative cells.
Key words Gene delivery, Gene vector, Adenovirus, Polyethylene glycol, PEGylation, Cellpenetrating peptides
1 Introduction
Adenovirus (Ad) is one of the most widely used gene delivery
vectors in gene therapy clinical trials [1] and has been proposed as
a vector capable of delivering DNA vaccines [2]. Most people,
however, possess neutralizing antibodies that inactivate the virus
[3]. In addition, systemic administration of high doses of Ad triggers an inflammatory immune response resulting in rapid clearance
of vector DNA from transduced tissues [4, 5]. Further, Ad relies on
interaction of the virus fiber and knob with the coxsackieadenovirus receptor (CAR) to initiate cellular attachment and ultimately infection. This reliance on the virus receptor limits the
ability of Ad to deliver genes to CAR-negative cells such cancer
cells, endothelial cells, epithelial cells, and smooth muscle cells
[6, 7].
For these reasons there is considerable interest in modifying
adenovirus to overcome these drawbacks. Approaches are typically
classified as either genetic or chemical modification of the virus. For
example, a common genetic approach to reduce immunogenicity is
to genetically replace Ad-5 (i.e., serotype 5) viral proteins, such as
Blaine A. Pfeifer and Andrew Hill (eds.), Vaccine Delivery Technology: Methods and Protocols, Methods in Molecular Biology,
vol. 2183, https://doi.org/10.1007/978-1-0716-0795-4_18, © Springer Science+Business Media, LLC, part of Springer Nature 2021
357