Aim-Nanoparticles based on plant viruses are emerging biomaterials for medical applications such as drug delivery and imaging. Their regular structures can undergo genetic and chemical modifications to carry large payloads of cargos, as well as targeting ligands. Of several such platforms under development, only few have been characterized in vivo. We recently introduced the filamentous plant virus, potato virus X (PVX), as a new platform. PVX presents with a unique nanoarchitecture and is difficult to synthesize chemically.Methods-Here, we present a detailed analysis of PVX biodistribution and clearance in healthy mice and mouse tumor xenograft models using a combination of ex vivo whole-organ imaging, quantitative fluorescence assays and immunofluorescence microscopy.Results & conclusion-While up to 30% of the PVX signal was from the colon, mammary and brain tumor tissues, remaining particles were cleared by the reticuloendothelial system organs (the spleen and liver), followed by slower processing and clearance through the kidneys and bile.Keywords anisotropic nanoparticle; biodistribution; immunogenicity; mononuclear phagocyte system; nanoparticle shape; polyethylene glycol; tumor homing; viral nanoparticle Plant viruses and bacteriophages have been recognized as potentially useful biomaterials for a range of nanomedical applications, including tissue-specific imaging, drug delivery and vaccine development [1]. Viruses are versatile because they are symmetrical, monodisperse protein structures that form icosahedrons, tubes or filaments, which encapsulate nucleic acids and deliver them efficiently to cells. They have evolved robust structures that withstand the adverse conditions present during infection, but remain responsive to subtle physiological parameters, such as pH and temperature, allowing them to disassemble and reassemble for self-propagation. These attributes can be exploited to develop virus-based nanoparticles (VNPs) that are amenable to chemical and genetic modification, allowing the incorporation of drugs, contrast and imaging probes, as well as targeting ligands conjugated to either the external or internal particle surface, or packaged inside through the use of induced disassembly and reassembly strategies [2]. The ease of production by molecular farming in plants makes VNP technology highly scalable. Shukla et al. Page 2 Nanomedicine (Lond). Author manuscript; available in PMC 2014 September 19.
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NIH-PA Author ManuscriptThe application and development of plant VNPs is still a relatively young discipline.Although various platforms have been tested and developed in the test tube (e.g., various modification strategies have been devised), only few examples have been characterized in vivo; principally, the icosahedrons cowpea chlorotic mottle virus (CCMV) and cowpea mosaic virus (CPMV) [3,4]. Both plant VNPs demonstrated rapid blood pool clearance and were detected in a wide variety of tissues throughout the body; CPMV accumulated primari...