Biology Reference
In-Depth Information
Chapter 4
Use of Dodecahedron “VLPs” as an Alternative
to the Whole Adenovirus
Pascal Fender
Abstract
During human adenovirus type 3 (Ad3) infection, an excess of penton base and fi ber proteins are produced.
These form dodecahedral particles composed of 12 pentamers of penton base and 12 trimers of fi ber pro-
tein. Beside this “natural” expression, the adenovirus dodecahedron can be expressed in the heterologous
baculovirus system in two forms: a fi ber-devoid dodecahedron made only of 12 penton bases (called base-
dodecahedron: Bs-Dd) and the fi ber-containing dodecahedron (called penton dodecahedron: Pt-Dd).
These particles partly mimic the adenoviral cellular entry pathway but are devoid of genetic information
making them an unusual tool for basic research or applications. We report here how these particles are
expressed and purifi ed, the labeling method for traffi cking studies as well as their use in molecular interac-
tion studies. The potential of these particles for biotechnological applications is under evaluation, making
their study a “niche” along side traditional adenoviral vectors.
Key words
Adenovirus, Dodecahedron, Vectorology, Virus-like particle, Protein transduction,
Traffi cking, Receptor identifi cation
1
Introduction
Even knowing that Adenoviruses can be produced at high titer
(about 10
12
vp/mL) compared to other viral vectors (10
8
vp/mL
in average), this is still far from being comparable with protein
yields in overexpression systems. One way to overcome this limita-
tion consists in obtaining “Virus-Like Particles = VLPs” derived
from the expression of one or several viral proteins expressed in
heterologous systems such as
E. coli
, yeast,
Baculovirus
, mamma-
lian cells or even plants (for review
see
ref.
1
). VLPs have been
reported for a number of single- or double-stranded RNA and
DNA viruses. To the best of our knowledge, all VLPs reproduce
the architecture of the virion capsid with the exception of the ade-
novirus dodecahedron (Ad-Dd). The adenovirus penton base and
fi ber form a non-covalent complex located at the 12 vertices of the
icosahedral capsid and separated by hexon capsomer facets. Indeed,
