Production of VNPs, VLPs, and Chimeras - Viral Nanoparticles: Tools for Materials Science and Biomedicine - page 56

and are available for straightforward modification, cloning, and production.
Yeast production is fast, cheap, and can be scaled up using fermentation
technology. The advantages of yeast over

are that yeast cells are able
to secrete soluble proteins and perform post-translational modifications,
such as proteolytic processing, phosphorylation, and glycosylation.

E. coli

Figure 3.3 Transmission electron micrographs comparing Cowpea chlorotic mottle

virus

expression system. (A) Wild-type CCMV containing RNA purified from cowpea plants
and (B) wild-type CCMV VLPs produced in the heterologous

(CCMV) purified from plants with CCMV VLPs purified from the P. pastoris

P. pastoris system. Mutants

∆

produced in the 34 = altered interior surface

charge (a range of particle sizes are observed) (C), SubE = deleted N-terminus (D),
CPPep11 = peptide insertion in surface-exposed loop (E), and 81/148 = alteration of
subunit interfaces at the metal binding sites (F). The scale bar is 100 nm. Reproduced
with permission from Brumfield, S., Willits, D., Tang , L., Johnson , J. E., Douglas, T., and,
Young, M. (2004) Heterologous expression of the modified coat protein of

P. pastoris expression system included N

Cowpea

chlorotic mottle bromovirus results in the assembly of protein cages with altered

architectures and function, J. Gen. Virol. , 85 (Pt 4), 1049-1053.

VLPs of the following viruses have been successfully produced in yeast:
the plant viruses BMV ( S. cerevisiae ) and CCMV ( P. pastoris ), as well as the

bacteriophage Q

b

( S. cerevisiae and P. pastoris ) (Brumfield et al. , 2004;

Freivalds , 1999). Intact VLPs are typically self-

assembled within yeast and can be isolated in high yields by cell lysis and
differential ultracentrifugation. Yields of up to 0.5 g VLP per liter cell culture

et al. , 2006; Krol et al.