Analyses of effects of heavy ion irradiation on expression of viral and cellular genes

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We have analyzed the infection mechanism of viruses, such as HIV-1, HBV or HCV, using cells irradiated with heavy ions and inoculated with them. As heavy ions, He, C or Ne was used and as controls, irradiation with UV or X-ray/γ ray, or treatment with various chemical compounds was used. As target cells for irradiation, the human cell lines C8166 and NP-2/CD4/CCR5 (NP2 cells transduced with CD4 and CCR5 genes), HBV-positive Alexander cell line or HCV replicon-positive Huh-7 line was used.The cells were irradiated with heavy ions and then infected with HIV-1. The amount of reverse transcribed viral DNA was increased in the irradiated cells. Irradiation with higher doses did not induce this increase. The amount of HIV-1 adsorbed to the cells did not increase significantly. These results suggest that irradiation of cells with relatively low doses of heavy ions will promote incorporation of HIV-1 virions or reverse transcription as well as transcription of viral RNA.Irradiation of C8166 ce … More lls harboring HTLV-I with heavy ions or X-ray enhanced expression of NFκB, whereas expression of HTLV-I Tax was not affected by the irradiation. In HBV-positive cells, heavy ion irradiation tended to enhance the production of HBV antigens. In HCV replicon-positive Huh-7 cells, heavy ion irradiation did not apparently affect the number of HCV replicon.In cells irradiated with heavy ions, expression of CD133 mRNA or NFκB mRNA was enhanced, whereas mRNA for histon deacetylase (HDAC), Ku80 or poly-ADP ribose polymerase was decreased.Analyses of susceptibilities of irradiated cells to virus infection showed the specific effects exerted by irradiation with heavy ions, but not by irradiation with UV or X-ray. The difference in biological effects between heavy ion irradiation and X-ray irradiation has generally been considered to be present merely in their relative biological effects (RBE). Our study suggested that there is a qualitical difference between irradion with heavy ions and X-ray or UV. Less