Thermal transition of native tobacco mosaic virus and RNA-free viral proteins into spherical nanoparticles

Spherical nanoparticles (SNPs) were generated by two-step thermal remodelling of native tobacco mosaic virus (TMV) at 94 degrees C. Particles of irregular shape and varying size were generated by TMV at 90 degrees C. They could be converted into SNPs by heating at 94 degrees C and were considered to be intermediate precursors of SNPs. In addition to SNP monomers (53 nm diameter), generated by individual TMV virions, large SNPs (100-800 nm diameter) were assembled. The size of the SNPs depended on the TMV concentration. The SNPs could be generated by distinct forms of RNA-free TMV coat protein (CP) aggregates and individual CP subunits. A one-step SNP assembly appeared to occur in these cases. These results show that SNPs represent a new type of particle nanoplatform for producing compositions of SNPs with foreign protein molecules bound to their surface.