Viruslike particles in liver in sporadic non-A, non-B fulminant hepatitis

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Identification of hepatitis C virus by immunoelectron microscopy

Sequencing of the hepatitis C virus (HCV) has provided a better understanding of the natural history, immunology, and epidemiology of this virus. However, the morphology of HCV has not been definitively characterized. In this study, through a sequence of concentration processes, virus-like particles were isolated from human serum and liver tissue, visualized by transmission electron microscopy and identified as hepatitis C virion by immunoelectron microscopy. Spherical flavi-like virus particles, approximately 70 nm in diameter, were observed in the fraction with 1.04-1.12 g ml-1 sucrose density and bound to immunogold particles with monoclonal antibodies (mAb) against hepatitis C. The nucleocapsid of the particles, which were 50 nm in diameter, appeared to be icosahedral in structure and surrounded by an envelope covered with surface projections. A 'tadpole' form of particles was also observed. The findings indicate that the low buoyant density in sucrose and the morphological features of the hepatitis C virion are consistent with the characteristics of flaviviruses and pestiviruses.

An ultrastructural study of six cases of chronic active C hepatitis. A comparison with chronic active B hepatitis

Liver biopsies from six patients affected by chronic active hepatitis (CAH) induced by hepatitis C virus (HCV) have been investigated ultrastructurally and their features compared with those of five cases of CAH induced by hepatitis B virus (HBV). Clusters of deeply packed nuclear inclusions (18 to 22 nm in diameter) were found in patients with HCV-CAH. They were irregularly round and ill-delimited. These inclusions were distinct from the regular round and well-delimited nuclear inclusions associated with HBV. HCV-associated nuclear inclusions were similar to a peculiar type of intranuclear particle described in non-A, non-B hepatitis before the HCV disease had been recognized as a distinct entity. These inclusions have never been hitherto reported in infections caused by HBV or other known hepatotropic viruses. Together, these data suggest that the occurrence of these inclusions can be related to HCV activity in hepatocytes. Changes in the microarchitecture of the liver cell and its microenvironment were similar in HCV- and HBV-CAH. They were heterogeneous in different cases and did not display a clear correlation with the severity of the disease.

Hepatitis C virus antibodies in acute and chronic liver disease in India

The prevalence of serum antibodies to hepatitis C virus was assessed by an enzyme-linked immunosorbent assay in patients with epidemic non-A, non-B hepatitis (14), sporadic non-A, non-B hepatitis (42), chronic hepatitis (14) and cirrhosis (26). None of the patients with epidemic non-A, non-B hepatitis (14) and acute self-limiting sporadic non-A, non-B hepatitis without prior parenteral exposure (38) tested positive for hepatitis C virus antibody. Based on epidemiologic features, hepatitis E virus is presumably the etiologic agent for both these entities. Hepatitis C virus (HCV) antibody was positive in none of the patients with cryptogenic chronic hepatitis (11) and in 2(8%) patients with cryptogenic cirrhosis (25). It was concluded that cryptogenic chronic hepatitis and cirrhosis in India may be caused by alternative viral agents of the non-A, non-B type or by hepatotoxins to which the population may be exposed. Of 8 patients with prior parenteral exposure (transfusions 6, needle pricks 2) 5 (62.5%) patients tested positive for HCV antibody. HCV antibody was detected in 1 (25%) patient with acute self-limiting, parenterally transmitted non-A, non-B hepatitis and in 4 (100%) patients with chronic parenterally transmitted non-A, non-B hepatitis.

Toga virus-like particles in acute liver failure attributed to sporadic non-A, non-B hepatitis and recurrence after liver transplantation

Toga virus-like particles (typically 60-70 nm: enveloped with small surface spikes) were detected in the native hepatectomy specimens in 7 of 18 patients grafted for acute liver failure attributed to sporadic non-A, non-B hepatitis and in 2 patients grafted for fulminant hepatitis attributed to anti-epileptic drug hepatotoxicity. These particles were not detected in the hepatectomies from 12 other patients grafted for other causes of acute liver failure, 12 for various chronic liver diseases, and 2 histologically normal livers. Acute hepatic failure, characterized histologically by severe haemorrhagic necrosis, developed 7 days after grafting in 5 patients, all in the non-A, non-B group with toga virus-like particles in native liver. Similar virus-like particles were detected in all grafts and were in greater abundance than in the native livers. The agent may be novel because pre- and post-grafting sera were negative for antibodies against representative panels of arboviruses and in first and second generation antibody tests for hepatitis C virus.

Detection of hepatitis C virus (HCV) RNA in paraffin embedded tissue sections of human liver of non-A, non-B hepatitis patients by in situ hybridization

Localization of hepatitis C virus (HCV) RNA was investigated by non-radioactive in situ hybridization in human liver specimens of chronic non-A, non-B (NANB) hepatitis patients who were seropositive for antibodies to HCV (anti-HCV). For in situ hybridization, T-T dimerized synthetic oligodeoxynucleotide probes were used and DNAs hybridized in situ were detected immunohistochemically using specific antibodies against T-T dimer. The data demonstrates that HCV-RNA was localized in the cytoplasm of hepatocytes in human liver biopsies obtained from the patients with chronic NANB hepatitis seropositive for anti-HCV.

Toga-like virus as a cause of fulminant hepatitis attributed to sporadic non-A, non-B

Virus-like particles (60-70 nm) with spiked surfaces budding into cell vacuoles and rod-shaped inclusions were detected in nuclei of hepatocytes from a British patient transplanted for sporadic non-A, non-B fulminant hepatitis (NANB-FHF), probably contracted in Kenya. Identical particles were seen in two successive grafts (days 2 and 10) at regrafting for recurrent FHF. Ultrastructural features resembled those of the RNA-containing arbovirus, Rift Valley fever virus, but serological markers against a representative panel for arboviruses (Togaviruses) and transmission in mice proved negative. The particles shared features with the different arboviruses seen in the hepatectomy specimen of a second patient with NANB-FHF, and in both patients an insect vector was implicated in the clinical history. The particles were identical in size to those of a third patient with NANB-FHF, who had remained in the United Kingdom. These findings, together with the recent report of isolation of an RNA-containing virus resembling the Togaviridae, in parenteral NANB, suggest that several exotic virus-like agents resembling the arboviruses may be involved in the aetiology of NANB, including in the sporadic forms of FHF in the United Kingdom.