A first step towards a mouse model for hepatitis C virus infection containing a human immune system

COMMENTARY ON: A humanized mouse model to study hepatitis C virus infection, immune response and liver disease. Washburn ML, Bility MT, Zhang L, Kovalev GI, Buntzman A, Frelinger JA, Barry W, Ploss A, Rice CM, Su L. Gastroenterology. 2011 Apr;140(4):1334–44. Copyright (2011). Abstract reprinted with permission from the American Gastroenterological Association. http://www.ncbi.nlm.nih.gov/pubmed/21237170 Abstract Background & Aims: Studies of hepatitis C virus (HCV) infection, immunopathogenesis, and resulting liver diseases have been hampered by the lack of a small animal model. We developed humanized mice with human immune system and liver tissues to improve the studies of hepatitis C pathogenesis and treatment. Methods: To promote engraftment of human hepatocytes, we expressed a fusion protein of the FK506 binding protein (FKBP) and caspase 8 under the control of the albumin promoter (AFC8), which induces liver cell death, in Balb/C Rag2 −/− γC-null mice. Co-transplantation of human CD34 + human hematopoietic stem cells (HSC) and hepatocyte progenitors into the transgenic mice led to efficient engraftment of human leucocytes and hepatocytes. We then infected these humanized mice (AFC8-hu HSC/Hep) with primary HCV isolates and studied HCV-induced immune responses and liver diseases. Results: AFC8-hu HSC/Hep mice supported HCV infection in the liver and generated a human immune T-cell response against HCV. HCV infection induced liver inflammation, hepatitis, and fibrosis, which correlated with activation of stellate cells and expression of human fibrogenic genes. Conclusions: AFC8-hu HSC/Hep mice are a useful model of HCV infection, the immune response, and liver disease, because they contain human immune system and liver cells. These mice become infected with HCV, generate a specific immune response against the virus, and develop liver diseases that include hepatitis and fibrosis. This model might also be used to develop therapeutics for HCV infection.