Hepatitis C Virus (HCV) Pathogenesis in Liver Transplant Recipients

David Gretch, MD, PhD

This research project (R29-NIAID) is studying the pathogenesis of chronic liver disease in humans infected with hepatitis C virus. HCV infection is a major cause of chronic liver disease and hepatocellular carcinoma, and chronic HCV infection is the leading indicator for liver transplant at the University of Washington Medical Center. The course of HCV infection in transplant patients closely parallels the clinical course of HCV in the non-transplant patient supporting the use of the liver transplant recipient as a model for studying the relationship between HCV replication and clinical disease in humans.

The specific aims of this project are to:

1. Determine if the level of HCV replication in the liver (quantity of viral RNA and non-structural antigens) is related to the extent of hepatocellular injury.
2. Determine if the tissue distribution and diversity of HCV quasispecies variants is related to the onset and histologic course of liver disease in the transplant recipient.

The levels of HCV replication and antigen expression in liver biopsy specimens from transplant recipients with recurrent HCV and from control transplant recipients with asymptomatic HCV infections are measured by quantitative PCR and immunohistochemistry, respectively. The levels of HCV RNA and antigen are then correlated with histopathologic evidence of liver injury in the same biopsy specimens. These studies are addressing the important question of whether hepatocyte injury is primarily a result of HCV replication in the liver.

HCV exists as a quasispecies in infected humans characterized by extensive mutation in the second envelope gene during the course of chronic infection. In this study, the experimental approach to analyzing HCV quasispecies is to amplify selected portions of the HCV genome by PCR, screen for structural changes by single-strand conformational polymorphism (SSCP), and analyze the region of interest using gel shift analysis (GSA). This study is tracing HCV quasispecies variants in the serum, liver and peripheral blood mononuclear cells during the course of post-transplant infection to determine if there is an affinity of particular HCV quasispecies variants for infection of liver and /or hematopoeitic tissues. These experiments are designed to clarify the role of HCV quasispecies during persistent infection, and to define the relationship between HCV quasispecies tissue tropism and the pathogenesis of post-transplant liver disease.

The investigators have recently demonstrated that relatively homogenous quasispecies variants do emerge after liver tranplantation and have preliminary evidence that major variants present in pretransplant serum are efficiently replicated following liver tranplantation and are propagated during the course of acute and chronic hepatitis.

Report courtesy of Anna Marie Beckmann

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Recent Publications

Gretch DR, Polyak SJ, Wilson JJ, Carithers RL Jr, Perkins JD, Corey L. Tracking hepatitis C virus quasispecies major and minor variants in symptomatic and asymptomatic liver transplant recipients. J Virol 1996; 70:7622-31.

Shuhart MC, Bronner MP, Gretch DR , Thomassen LV, Wartelle CF, Tateyama H, Emerson SS, Perkins JD, Carithers Jr RL. Histological and clinical outcome after liver transplantation for hepatitis C. Hepatology 26(6):1646-1652, 1997.