Biology Reference
In-Depth Information
2007). More details and insights on the use of viruses in vaccine development
are given in Chapter 8.
In the 1980s researchers began exploiting plant viruses as expression
vectors (a DNA-based plasmid that promotes the expression of foreign
genes) to produce pharmaceutical proteins in plants. Advantages of protein
production in plants are the absence of contamination with animal products,
low production costs, and — when using viral expression vectors —
achievement of high expression levels. A range of pharmaceutically relevant
proteins including therapeutic antibodies have been successfully produced
using viral vectors such as TMV, CPMV, and
Potato virus X
(PVX) (Awram
et
al.
, 2002; Canizares
et al.
, 2005; Johnson
et al.
, 1997; Porta & Lomonossoff,
1998; Scholthof
, 1996).
Viruses Became VNPs.
et al.
Beginning about 20 years ago, the focus on
exploiting viruses and their capsids for biotechnology began to shift
toward using them for nanotechnology applications. Douglas and Young
(Montana State University, Bozeman, MT, USA) were the first to consider
the utility of a virus capsid as a nanomaterial (Douglas & Young, 1998).
The virus of interest in their studies was the plant virus
Cowpea chlorotic
mottle virus
(CCMV). CCMV is a highly dynamic platform with pH- and
metal ion-dependent structural transitions (see Section 2.2.2). Douglas
and Young made use of these capsid dynamics and exchanged the natural
cargo (nucleic acid) with a synthetic material, in this case encapsulating
the organic polymer polyanetholesulfonic acid. Since then many materials
have been encapsulated into CCMV and other VNPs (discussed in detail
in Chapter 5). The system was further engineered to allow not only the
entrapment of materials but also the size-constrained and spatially
controlled synthesis of materials within both the capsid and other protein
cages (discussed in Chapters 5 and 6). A protein cage is a hollow, generally
spherical protein structure that is typically assembled by multiple copies of
protein monomers and thus has similarities to a viral capsid.
At about the same time, the research team led by Mann (University of
Bristol, UK) pioneered a new area using the rod-shaped particles of TMV. The
particles were used as templates for the fabrication of a range of metallized
nanotube structures using mineralization techniques (Shenton
, 1999).
These techniques have received great attention during recent years. In
particular the contributions of Belcher and colleagues at the Massachusetts
Institute of Technology (MIT, Cambridge, MA, USA) led to the development
of a new technology that allowed for the generation of a large range of
mineralized nanotubes and nanowires for use in batteries and data storage
devices (Lee
et al.
et al.
, 2009; Nam
et al.
, 2006; Nam
et al.
, 2008). Mineralization
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