Novel Strategy for Inhibiting Viral Entry by Use of a Cellular Receptor-Plant Virus Chimera

Abstract

The plant virus cowpea mosaic virus (CPMV) has recently been developed as a biomolecular platform to display heterologous peptide sequences. Such CPMV-peptide chimeras can be easily and inexpensively produced in large quantities from experimentally infected plants. This study utilized the CPMV chimera platform to create an antiviral against measles virus (MV) by displaying a peptide known to inhibit MV infection. This peptide sequence corresponds to a portion of the MV binding site on the human MV receptor CD46. The CPMV-CD46 chimera efficiently inhibited MV infection of HeLa cells in vitro, while wild-type CPMV did not. Furthermore, CPMV-CD46 protected mice from mortality induced by an intracranial challenge with MV. Our results indicate that the inhibitory CD46 peptide expressed on the surface of CPMV retains virus-binding activity and is capable of inhibiting viral entry both in vitro and in vivo. The CD46 peptide presented in the context of CPMV is also up to 100-fold more effective than the soluble CD46 peptide at inhibiting MV infection in vitro. To our knowledge, this study represents the first utilization of a plant virus chimera as an antiviral agent.Global control of infectious diseases is dependent upon the development of novel, inexpensive and easily produced vaccine and antiviral reagents. In regions where infections are endemic, the use of appropriate antimicrobial reagents is largely limited by cost and the lack of equipment and facilities for appropriate delivery of the reagents. The use of plant viruses such as the cowpea mosaic virus (CPMV) as biomolecular platforms for designing antiviral agents and vaccines overcomes many of these obstacles. CPMV provides the advantages of inexpensive production of large quantities of material, with up to 1 to 2 g of virus produced per kilogram of infected cowpea plants. In addition, plant virus particles are generally stable to extremes of temperature and pH; for example, CPMV can withstand temperatures up to 60°C and pH levels as low as 1.0 to 2.0 (18), and this stability is an advantage for use in tropical and/or rural areas, where continuous refrigeration is not readily available. Finally, the lack of contaminating animal cells and viruses in plant reagent preparations is beneficial.The CPMV chimera technology for presenting heterologous peptides is based on the crystal structure of the virus capsid (3, 9). The CPMV capsid consists of 60 copies each of a large (L) and small (S) protein that are arranged with icosahedral symmetry. One L protein consisting of two jelly roll ␤-barrels and one S protein consisting of a single jelly roll ␤-barrel make up the asymmetric unit of the capsid. There are three copies of the L protein arranged around each threefold axis of symmetry, and five copies of the S protein are arranged around each fivefold axis of symmetry. In the S protein, surface-exposed loops that do not appear to be involved in intersubunit contact exhibit high variability among different members of the comovirus family of plant viruses, of which CPMV i...

Nanoparticle-Templated Assembly of Viral Protein Cages

“…1,2 Due to their intrinsic symmetry, these arrays can provide high density and equivalent environments for binding domains, characteristics that are difficult to achieve by any other technologies. 3 The ability to engineer specific regulatory switches into proteins by use of recombinant DNA technology also promises additional uses in these arrays.The protein coat, or capsid, of many viruses provides a discrete analogue to extended protein assemblies on planar surfaces. As a consequence, modified-virus capsids have been proposed as versatile biomolecular platforms for displaying engineered peptide sequences for triggering specific host responses.…”

Core-controlled polymorphism in virus-like particles

“…Indeed, Fig. 1 A indicates that, at low CP/Au ratios, VLP 6 forms with greater efficiency than VLP 12 . VLP Size Determined by Atomic Force Microscopy (AFM) and Spectroscopy.…”

“…For VLP 12 , there are typically Ͻ5% empty capsids and very few naked gold particles (Ͻ1% of the total amount of gold). VLP 6 and VLP 9 also yielded preparations homogeneous in size and shape (SI Fig. 6).…”

“…The VLP 6 and VLP 9 3D reconstructions clearly lack hexamers and therefore are associated with a different structure than T ϭ 3. Thus, VLP 9 is similar to a pseudoT ϭ 2 arrangement previously determined for the RNA-controlled 120-unit BMV capsid (24) (Fig.…”

“…increasing promise as therapeutic and diagnostic vectors (1)(2)(3)(4)(5)(6), imaging agents (7)(8)(9)(10), and as templates and microreactors for advanced nanomaterials synthesis (11)(12)(13)(14)(15)(16)(17). Here, we address the rules for the formation of symmetric protein cages consisting of viral capsid subunits formed over a functionalized inorganic nanoparticle core, called virus-like particles (VLPs).…”