Cowpea mosaic virus (CPMV) ELISA Kit

Cowpea mosaic virus (CPMV) can cause a cowpea virus disease that produces yellow-green blotches on the leaves, followed by a gradual protrusion of the densely green areas in the form of warts, and leaf deformities. This is a picorna-like virus belonging to the order Picornavirales, family Secoviridea, genus Comoviridae. The virus contains an icosahedral capsid, approximately 30 nm in diameter, with a net negative surface charge. The internal genome consists of two parts, RNA-1 and RNA-2, of positive-sense RNA. RNA is absent from approximately 10 per cent of wild-type, intact virus particles. These CPMV particles were separated into top (T), middle (M) and bottom (B) bands using density gradient centrifugation for empty (CPMV-T), RNA-2 carrying (CPMV-M) and RNA-1 carrying (CPMV-B) particles, respectively. RNA-1 encodes proteinase K cofactor (ProC), helicase, viral genome-linked protein (Vpg), 24K protease, and RNA-dependent RNA polymerase. RNA-2 encodes the 48/58 K movement protein and VP60, the latter of which can be cleaved post-translationally by the 24K protease to form two capsid subunits, L and S.

Figure 1. The CPMV bipartite RNA genome organization
(Source: Beatty PH, et al. 2019)

Due to the many properties of CPMV nanoparticles, such as non-pathogenicity, biocompatibility, and biodegradability, the virus has become a good candidate for chemical and genetic engineering to develop cancer imaging and therapeutic tools. For in vivo production of CPMV, leaves of V. unguiculata plants grown for 10 days were mechanically infected. A mixture of abrasive and CPMV particles carrying RNA-1 and RNA-2, respectively, was lightly sprinkled on the leaves, and after 10 days of plant growth, CPMV-infected leaves were harvested and stored at -80°C. The CPMV particles were then purified from the aqueous fraction of the homogenised leaves by several centrifugation processes, resulting in a crude purified product. Subsequently purified to homogeneous CPMV particles by sucrose gradient ultracentrifugation and size-exclusion fast protein liquid chromatography (FPLC). Non-replicative CPMV particles can be produced in vitro by exploiting the RNA genome-independent self-assembly properties of the L and S subunits that make up the capsid. Their production methods can be trans expression using highly expressed plasmids or mixing and reassembling of purified subunits on a cell-free protein synthesis platform.

Nanomedicines, as improved drug delivery vehicles with high specificity and sensitivity, can preferentially target cancer cells and even reach sites that are difficult to penetrate by conventional means. The bioavailability of CPMV was tested in a mouse model by intravenous or oral administration, and the results showed that nanoparticles were found in almost all tissues by both methods of administration. Particularly with oral administration, CPMV nanoparticles remained stable in the stomach, and since they were detected throughout the mouse, CPMV appeared to cross the gastrointestinal epithelium by interacting with Peyer's patches.