Pathogenesis in immunocompetent mice with persistent HCV expression.

<p>(<b>A</b>) Structure of CN2-29^(+/−)/MxCre^(+/−) and the Cre-mediated activation of the transgene unit. R6CN2 HCV cDNA was cloned downstream of the CAG promoter, neomycin-resistant gene (<i>neo</i>), and poly A (pA) signal flanked by two <i>loxP</i> sequences. This cDNA contains the core, E1, E2, and NS2 regions. (<b>B</b>) Cre-mediated genomic DNA recombination. After poly(I:C) injection, genomic DNA was extracted from liver tissues and analyzed by quantitative RTD-PCR for Cre-mediated transgenic recombination. The transgene was almost fully recombined in transgenic mouse livers 7 days after the injection. In all cases, n = 3 mice per group. (<b>C</b>) HCV core protein expression was sustained for at least 600 days after poly(I:C) injection. (<b>D</b>) Immunohistochemical analysis revealed that most hepatocytes expressed the HCV core protein within 6 days after injection. (<b>E</b>) Liver sections from CN2-29^(+/−)/MxCre^(+/−) mice after the poly(I:C) injection. Infiltrating lymphocytes (arrows) were observed on days 6 and 180; Hepatocellular carcinoma (HCC) was observed on day 360. In contrast, these pathological changes were not observed in CN2-29^(+/−)/MxCre^(−/−) mice after the injection. The inset image shows abnormal mitosis in a tumor cell. (<b>F</b>) Hepatocyte swelling and abnormal architecture of liver-cell cords (silver staining), as well as abnormal glycogen accumulation (PAS staining) were observed on day 90 in CN2-29^(+/−)/MxCre^(+/−) mice. We observed steatosis (oil-red-O staining) on day 180 and, subsequently, fibrosis (Azan staining) on day 480. The scale bars indicate 50 µm.