Detection of widespread hepatocyte infection in chronic hepatitis C

Abstract

The controversial question of the extent of hepatocyte infection in chronic hepatitis C was re-examined in both chimpanzees and humans using a newly modified in situ hybridization (ISH) method for detecting hepatitis C virus (HCV) RNA. The specificity of the methodology for distinguishing positive-and negative-strand synthetic HCV RNA was at least six magnitudes greater than the reversetranscription polymerase chain reaction (RT-PCR) assay for HCV. The sensitivity of the methodology as determined by cell culture assay was l4 ؎ 2 genomic equivalents (gE) of HCV positive strand per cell, which was three magnitudes less sensitive than RT-PCR quantitation of HCV. In contrast to previous studies in both humans and chimpanzees with chronic hepatitis C, a high percentage of hepatocytes positive for both positive-and negative-strand HCV RNA was found in most specimens studied. In humans, the extent of hepatocyte infection varied with histological activity index (HAI). In the two chimpanzees studied, the liver biopsies showed minimal histological disease activity, but high percentages of hepatocytes were HCV-positive by ISH that correlated with hepatocyte ultrastructural changes associated with HCV infection. Hepatocyte infection was confirmed by RNA extraction and RT-PCR techniques for detecting HCV RNA that minimize the false detection of negative strands. In both human and chimpanzee liver biopsies showing minimal HAI, the hepatocyte concentration of HCV was estimated to be very low. These findings suggested the hypothesis that persistent infection in the liver may be caused in part by low-level HCV replication. The theoretical and clinical implications of these findings are discussed. (HEPATOLOGY 1998;28:573-584.)Extensive in situ hybridization (ISH) and immunohistochemical studies of chronic hepatitis C in humans have found that only small percentages of hepatocytes are infected. A study of two chimpanzees in which chronic hepatitis C developed after acute infection (Dr. Robert Purcell, personal communication) demonstrated, using ISH, that RNA was present in most hepatocytes within 2 days of infection but was no longer detectable at 20 weeks. 1 Studies of chronic hepatitis C in humans using ISH for detection of hepatitis C virus (HCV) RNA or immunohistochemical techniques for detection of HCV antigens in the liver produced some conflicting results with both techniques, but the findings in most of the studies using these two different methodologies were similar, with approximately 50% and 70% of liver specimens positive and less than 5% and 10% of hepatocytes positive by ISH and antigen detection, respectively. 2 Recent electron-microscopic studies for HCV were also consistent with previous in situ studies; HCV particles were rarely found in acute hepatitis C in chimpanzees and not at all in chronic hepatitis C in humans. 3 The finding of only small percentages of hepatocytes positive for HCV in chronic hepatitis C is puzzling because the most prominent pathological effect of HCV infection is hepatitis. In preliminar...

Hepatitis C virus cell-cell transmission in hepatoma cells in the presence of neutralizing antibodies

“…Identification of HCV-infected cells within the liver has been difficult to demonstrate with conflicting reports, and this makes viral production rates difficult to ascertain. [27][28][29] A recent report by Gale and colleagues 30 demonstrated focal areas of infected cells within the liver that were consistent with our in vitro observations. 30 Plasma from HCV-infected individuals has been reported to infect chimpanzees 31 and mice bearing chimeric human livers, 32 and this suggests that transmission between hosts is most likely mediated via cell-free virus.…”

Intragraft localization of activated nuclear factor κB in recurrent hepatitis C virus disease following liver transplantation

“…Substantial data have documented the hepatocellular localization of the HCV RNA and protein not only within the liver of nontransplant HCV-infected individuals [46][47][48][49] but within HCV-infected liver allografts as well. 8,42 The presence of HCV antigens within hepatocytes of infected allografts through a yet unidentified mechanism triggers the hepatocellular activation of NF-B.…”

DC-SIGN and L-SIGN Are High Affinity Binding Receptors for Hepatitis C Virus Glycoprotein E2

“…The majority of infected patients are unable to clear the virus, and many develop chronic liver disease, cirrhosis, and hepatocellular carcinoma (2). Replication of the HCV genome could be demonstrated in vivo and in vitro in liver hepatocytes (3,4) and hematopoietic cells including dendritic cells and B cells (5,6). However, the molecular mechanism by which the virus targets to these sites of replication, notably in the liver, is not known.…”