Gunther Kletetschka, Vojtech Zila, Sandrita Huerfano

The capsid of non-enveloped mouse polyomavirus (PyV) has 45 nm in diameter. Its outer shell is composed of 72 pentamers of the major structural protein VP1, arranged in icosahedral lattice. VP1 is able to spontaneously self-assemble into virus-like particles (VLPs) either during its expression in insect or yeast cells, or in vitro, from purified VP1 pentamers. Through the interactions of VP1 with sialysed ganglioside receptor, VLPs enter a variety of cell types including human cells, with the efficiency comparable with that of the native virions. PyV-based VLPs are broadly studied as potencial tool for delivery of genes for expression or for the imunotherapy. We utilize the PyV VLPs produced in insect cells, as carriers for delivery of carbon nanotubes (CNTs) into the mammalian cells. This is done by optimizing the conditions for efficient disassembly of VLPs (by using reducing agents) and re-assembly of VP1 pentamers into the VPLs in the presence of CNTs (by using of various buffers). The efficiency of the disassembly of VP1-VLPs in reducing conditions (dithiothreitol + EGTA) and re-assembly after dialysis of VP1 material into the two different buffers was described for re-assembly of VP1 pentamers of simian virus 40 (SV40) [1] In our work we used both buffers and VP1 pentamers were able to re-assemble into the capsid structures, however, the amount of newly assembled structures was low in contrast to high amounts of VP1 pentamers, still present in suspension. Additionally, after dialysis into the buffer containing (NH4)2SO4 we observed in adition to capsids also large aggregates of VP1 protein. Further, the optimalisation of re-assembly condition has to be performed to be able to get higher efficiency of re-assembly. [1] Kanesashi S, Ken-ichiro I, Masa-aki K, Song-iee H, Satoru T, Hajime W , Kohsuke K, HandaH (2003) Simian virus 40 VP1 capsid protein forms polymorphic assemblies in vitro. J Gen Virol, 84: 1899–1905.

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carbon nanotubes