An RNA virus, designated hepatitis G virus (HGV), was identified from the plasma of a patient with chronic hepatitis. Extension from an immunoreactive complementary DNA clone yielded the entire genome (9392 nucleotides) encoding a polyprotein of 2873 amino acids. The virus is closely related to GB virus C (GBV-C) and distantly related to hepatitis C virus, GBV-A, and GBV-B. HGV was associated with acute and chronic hepatitis. Persistent viremia was detected for up to 9 years in patients with hepatitis. The virus is transfusion-transmissible. It has a global distribution and is present within the volunteer blood donor population in the United States.

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Reports of cerebral dysfunction in chronic hepatitis C virus (HCV) infection have led to the suggestion that HCV may infect the central nervous system (CNS). We used reverse transcription-PCR, cloning, and sequencing to define quasispecies for the HCV internal ribosomal entry site (IRES) and hypervariable region 1 (HVR1) in autopsy-derived brain, liver, lymph node, and serum samples. There was evidence of tissue compartmentalization of sequences in the brain in two patients, with between 24 and 55% of brain-derived IRES sequences absent from the serum, and significant phylogenetic and phenetic clustering of the brain and lymph node HVR1 sequences. The IRES initiates cap-independent translation of the viral polyprotein. Two unique brain-derived IRES mutations (C 204 3A and G 243 3A), which have previously been associated with lymphoid replication and altered translational efficiency in cell culture, were found in one patient. We used a dicistronic reporter vector to test whether brain-derived variants showed altered IRES-mediated translational efficiency, which might favor CNS infection. The translational efficiencies of the brain-derived IRES sequences were generally reduced compared to those of the master serum and liver sequences in rabbit reticulocyte cell lysates and two human cell lines, HuH7 (liver) and CHME3 (microglial). The C 204 3A and G 243 3A mutations showed preserved translational efficiency in HuH7 cells but reduced efficiency in CHME3 cells. Our data provide evidence that the CNS is a site of HCV replication, consistent with the recent demonstration of negative-strand HCV RNA in brain, and suggest that IRES polymorphisms may be important as a viral strategy of reduced translation to favor latency in the CNS.

Previous studies have suggested that hepatitis B virus (HBV) variants may account for the presence of HBV DNA in hepatitis B surface antigen (HBsAg)-negative patients (occult HBV infection). However, it is not known how widespread these variants are and how they influence the course of liver disease. To determine the prevalence of variants within the major hydrophilic region (MHR) of HBsAg, we investigated 2,565 subjects, including subjects with chronic hepatitis, cryptogenic cirrhosis, hemodialysis patients, and blood donors. Chronic hepatitis B virus (HBV) infection is a global public health problem that affects over 300 million individuals, or 5% of the world's population.

Delayed seroconversion in HIV-positive individuals with acute HCV may result in delayed diagnosis and treatment. Where there is a clinical suspicion of recent HCV infection, for example, elevated alanine transaminase levels, HIV-infected patients should be screened for HCV RNA by RT-PCR.

Hepatitis B virus DNA (HBV DNA) in serum was measured by a Spot hybridization technique in a consecutive series of 79 cases with chronic HBV infection from Taiwan. HBV DNA was found in 96.3% (52/54) of HBeAg-positive, 66% (2/3) with neither HBeAg or anti-HBe and in 63.6% (14/22) of anti-HBe positive patients. The levels of HBV DNA in the HBe-Ag-positive patients were significantly higher than in the anti-HBe positive patients (median, 944 vs. 58 pg per ml, p less than 0.001). The mean ages increased from 28.7 years for the cases with high levels of HBV DNA, to 34.7 years for those with low levels (p less than 0.01) and to 41.0 years in those without HBV DNA in serum (p less than 0.05 when compared with those with low level of HBV DNA). Ninety per cent of patients (27/30) with high levels of HBV DNA showed only minor hepatic inflammatory activity, as did 91% (10/11) of those without HBV DNA. In contrast, histologic signs of chronic active hepatitis or chronic lobular hepatitis were demonstrated in 76% of cases (29/38) with low levels of HBV DNA. These data are consistent with the hypothesis that liver damage occurs during the period of clearance of hepatocytes supporting HBV replication, and are inconsistent with the view that HBV may be directly cytopathic. Thus, the natural history of chronic HBV infection may be divided into three phases.(ABSTRACT TRUNCATED AT 250 WORDS)

ObjectiveAn epidemic of acute hepatitis C virus (HCV) infection in HIV-positive men-who-have-sex-with-men (MSM) is emerging in Europe, Australia and the USA. The aim of this study was to characterise the natural history of primary HCV in this setting and to assess host and viral factors which predict spontaneous clearance.MethodsThis prospective longitudinal cohort study was carried out in 112 HIV-positive patients who were followed in a single centre (the St Mary's Acute HCV Cohort). Plasma and peripheral blood mononuclear cells (PBMCs) were obtained at monthly intervals for 3 months and at 3-monthly intervals thereafter for a median of 45 months (IQR=29–69 months). The primary end point was spontaneous clearance of HCV. Cox regression was used to assess the impact of clinical and virological variables on outcome, including liver function, CD4 count, rate of HCV RNA decline, T cell response and clonal sequence evolution within the HCV E2 envelope gene.Results15% of patients cleared HCV spontaneously, while 85% progressed towards chronicity. The latter group included a significant proportion of ‘fluctuating’ progressors (37.5%), in whom a fall followed by a rise (>1 log10) in viraemia was observed. This was associated with superinfection with new HCV strains and partially effective T cell responses. Spontaneous clearance was strongly associated with a 2.2 log10 viral load drop within 100 days of infection (HR=1.78; p<0.0001), elevated bilirubin (≥40 μmol/l; HR=5.04; p=0.006), elevated alanine aminotransferase (ALT; ≥1000 IU/ml; HR=2.62; p=0.048) and baseline CD4 count ≥650×106/l (HR=2.66; p=0.045), and only occurred in patients with genotype 1 infection. Evolution to spontaneous clearance occurred in patients with low viral diversity in the presence of an early multispecific T cell response.ConclusionsSpontaneous clearance of acute HCV in HIV-positive men can be predicted by a rapid decline in viral load, high CD4 count, elevated bilirubin and ALT, and is associated with low viral diversity and strong T cell responses.