Stability of plant virus-based nanocarriers in gastrointestinal fluids.

Alberto Berardi,David J Evans,Francesca Baldelli Bombelli,George P Lomonossoff

doi:10.1039/c7nr07182e

Abstract

Cowpea mosaic virus (CPMV) is a plant virus which is being extensively investigated as a drug delivery and vaccine nanocarrier for parenteral administration. However, to date little is known about the suitability of plant-based nanocarriers for oral delivery. In this study, the colloidal (i.e. aggregation), physical (i.e. denaturation) and chemical (i.e. digestion of the polypeptides) stability of CPMV and its empty virus-like particles (eVLPs) in conditions resembling the gastrointestinal fluids were evaluated. The nanoparticles were incubated in various simulated gastric and intestinal fluids and in pig gastric and intestinal fluids. CPMV and eVLPs had similar stabilities. In simulated gastric media, they were stable at pH ≥ 2.5. At lower pH destabilisation of the particle structure occurred, which, in turn, rendered the polypeptides extremely sensitive to pepsin digestion. However, both CPMV and eVLPs were stable in simulated intestinal fluids, in pig gastric fluids and in pig intestinal fluids. Thus CPMV, despite being a protein-based nanoparticle, was much more resistant to the harsh GI conditions than soluble proteins. Remarkably, both CPMV and eVLPs incubated in pig gastric and intestinal fluids were not subject to protein adsorption, with no formation of a detectable protein corona. The lack of a protein corona on CPMV and eVLP surfaces in GI fluids would imply that, if orally administered, these nanoparticles could maintain their native surface characteristics; thus, their biological interactions would remain predictable and unchanged. In summary, CPMV and eVLPs can be considered promising nanocarriers for applications requiring oral delivery, given their chemical, physical and colloidal stability and lack of protein adsorption from the environment in most of the tested conditions.

Highlights

Cowpea mosaic virus (CPMV) is a plant picornavirus with icosahedral shape and a diameter of 30 nm
CPMV, and its empty virus-like particles,[4] have been extensively studied for use in nanomedicine: it is known that CPMV selectively binds vimentin receptors, which are overexpressed on the surface of endothelial and cancer tissues, potentially enabling the delivery of bio-imaging agents or anticancer agents to those tissues.[5,6]
When CPMV was exposed to pH 1.2 and the pH was neutralised, the L and S proteins could not be detected in any fraction; a precipitate containing the L and S proteins could be found at the bottom of the centrifugation tube (Fig. 1B – right)

Summary

Introduction

Cowpea mosaic virus (CPMV) is a plant picornavirus with icosahedral shape and a diameter of 30 nm. The capsids are made up of 60 copies each of a small (S) and large (L) proteins, naturally encapsulating two positive sense RNA molecules.[3] CPMV, and its empty virus-like particles (eVLPs),[4] have been extensively studied for use in nanomedicine: it is known that CPMV selectively binds vimentin receptors, which are overexpressed on the surface of endothelial and cancer tissues, potentially enabling the delivery of bio-imaging agents or anticancer agents to those tissues.[5,6] Both CPMV7,8 and eVLPs9 have been loaded with various compounds, including cytotoxic agents. CPMV has been used in vaccinology as a scaffold for the display of heterologous immunogenic epitopes against animal pathogens.[10] eVLPs have been use as drug and vaccine carriers, and as cancer immunotherapy agents.[11 ] Paper

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Conclusion