Demonstration of Duck Hepatitis B Virus in Bile Duct Epithelial Cells: Implications for Pathogenesis and Persistent Infection

Abstract

ogy, genomic organization, and replication by means of reHepatitis B virus (HBV) has been demonstrated in bile verse transcription. 1,3 duct epithelial cells (BDEC) during chronic infection.The replication of human HBV has been extensively studThe persistence of virus in BDEC may play an important ied in hepatocytes, but comparatively less is known about role in disease pathogenesis, and may be at least partly HBV infection of nonparenchymal cells within the liver. Hepresponsible for the relapse phenomenon observed in adnaviral antigens have been shown in bile duct epithelial antiviral treatments using nucleoside analogues. The cells (BDEC) in both human 7,8 and animal 9,10 livers, but the aims of this study were to examine the morphological significance of these findings has not been fully determined. changes within the liver in the duck hepatitis B modelThe HBV life cycle is complex, and there is evidence that following bile duct ligation (BDL), and to assess the efit may vary depending on the cell type, such as lymphoid fect of biliary hyperplasia upon viral DNA and proteins.cells compared with hepatocytes. 11-15 Also, HBV replication Seven-day-old ducklings, congenitally infected with the appears to be cell-cycle dependent with enhanced viral repliduck hepatitis B virus (DHBV), were subject to BDL. The cation occurring in quiescent compared with proliferating hepathological and virological changes were then followed patocytes. 16 Recent studies have shown that HBV replication at 5, 10, 15, and 20 days after ligation. All results were is inversely correlated with cellular DNA synthesis with noncompared with age-matched unligated control birds cytolytic cell arrest resulting in increased viral expression. 1.3 days. The proliferated BDEC displayed immunohistoTherefore, the interaction of HBV with BDEC warrants more chemical features identical to resting BDEC. More than detailed investigation. The aim of the present study was to 50% of BDEC in unligated controls, and more than 46% characterize DHBV infection in BDEC of congenitally inof proliferated BDEC in ligated animals were positive fected animals, and to examine the effect of cell division on for DHBV DNA and structural proteins. The intensity of hepadnaviral proteins and DNA in proliferating BDEC using immunohistochemical staining and in situ hybridization immunohistochemistry and in situ hybridization, respecsignal in the BDEC was consistently greater than that tively. of the hepatocytes, both before and after BDL. BDL induces biliary hyperplasia in the duck model, and BDEC MATERIALS AND METHODS division does not reduce the viral burden in infected cells. (HEPATOLOGY 1997;25:463-469.)Animals and Experimental Strategy. One-day-old Pekin-Aylesbury ducklings, congenitally infected with an Australian strain of DHBV, were obtained from a commercial supplier.17 Viraemia was monitored by dot blot hybridization as previously described.9,18 Thirty-eight conInfection of Pekin-Aylesbury ducks with the duck hepatitis genitally infected ducklings aged between 7 and 9 ...

In Vitro Antihepadnaviral Activities of Combinations of Penciclovir, Lamivudine, and Adefovir

“…Using immunohistochemical and in situ DNA hybridization techniques, it was found that treatment with PMEA reduced viral protein and DNA loads in bile duct epithelial cells (BDEC) as well as hepatocytes (30). This observation is significant because the reservoir of DHBV in BDEC is refractory to treatment with nucleoside analogs such as PCV and 3TC, presumably because BDEC lack the enzymatic machinery required for their uptake or phosphorylation (29,30). Since it is a dAMP analog, PMEA is able to bypass the initial phosphorylation site, which is critical and often limiting for the activity of most nucleoside analogs (32,33) (Fig.…”

“…Viremia was monitored by serum dot blot hybridization as previously described (7). Primary hepatocytes were obtained from livers of 7-to 14-day-old congenitally infected or virus-free ducklings and seeded into 12-well plastic culture plates (ICN Biomedicals, Aurora, Ohio) at a density of approximately 0.75 ϫ 10 6 to 1.0 ϫ 10 6 PDH per well (7,29). PDH were allowed to attach overnight before the first medium change (on day 1 postplating) and were maintained at 37°C in a humidified incubator under 5% CO 2 with medium changes every second day (7).…”

“…This phenomenon is attributable to two important characteristics of chronic hepadnaviral infection: (i) the potential for reinitiation of infection by viral particles released from cell and tissue sites which may act as sanctuaries for potentially infectious virus, even during aggressive antiviral therapy (26,29,30), and (ii) the persistence of intranuclear viral supercoiled, covalently closed circular (CCC) DNA, the hepadnaviral genomic species which serves as the template for transcription of viral mRNA (mediated by host cell RNA polymerase II) but which is only indirectly involved in DNA replication and is minimally affected by deoxynucleoside triphosphate (dNTP) analogs (8). These characteristics ensure that chemotherapeutic control of chronic HBV infection is most likely to require long-term treatment.…”

Hepatitis B Virus Biology

“…Hepatocytes are the only confirmed site of replication for all members of this virus family. Bile ductule epithelial cells may also be a target of infection, as may a subset of cells in the pancreas, kidneys, and lymphoid system (16,74,77,98,111,122,151,160,170,187,243). However, the evidence for replication of the orthohepadnaviruses in bile ductules and at extrahepatic sites is in some cases controversial or incomplete, and these sites are not usually considered in discussions of viral reproduction and pathogenesis.…”

Intrahepatic HBV DNA as a predictor of antivirus treatment efficacy in HBeAg-positive chronic hepatitis B patients

“…Relapse occurs in the majority of patients after therapy. The main reason is that HBV covalently closed circular DNA (cccDNA) in infected hepatocytes cannot be eliminated by antiviral agents, leading to rebound of HBV DNA after antiviral therapy [18] . The life cycle of HBV relies on a covalently closed circular form of the viral genome, which provides the template for viral pregenomic messenger RNA.…”