Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To evaluate the risk of transmitting blood-borne GB virus C/hepatitis G virus (GBV-C/HGV) and to define the natural course of infection, we performed a prospective study in a cohort of multitransfused beta-thalassemics during a 6-year follow-up period. We analyzed serum samples of 150 patients collected at 3-year intervals from 1990 to 1996. GBV-C/HGV RNA was determined by reverse transcriptase-polymerase chain reaction and antibodies to E2-protein by an enzyme immunoassay. At baseline, 14.5% of patients had viremia and 18.5% anti-E2. None of the patients with anti-E2 in 1990 subsequently became viremic. Of the 100 GBV-C/HGV RNA-, anti-E2- patients, 10 acquired infection during follow-up, as indicated by positivity of GBV-C/HGV RNA (n = 2), anti-E2 (n = 7), or both markers (n = 1) in 1996. The incidence was 1.7 per 100 person-years (95% confidence interval [CI], 0.8 to 3). Since approximately 19,000 blood units were transfused to these patients during follow-up, the risk of infection was 5.3 in 10,000 units (95% CI, 2 to 8.5). Six of 22 viremic patients cleared the virus during follow-up; 4 of them became anti-E2+. Twelve of 28 patients lost anti-E2 reactivity during follow-up. In conclusion, more than 25% of infections resolve within 6 years; the presence of anti-E2 seems to be protective against infection. Anti-E2 reactivity may decrease with time.
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PMID:The incidence and natural course of transfusion-associated GB virus C/hepatitis G virus infection in a cohort of thalassemic patients. The Cooleycare Cooperative Group. 944 35

The aim of this study was to determine the prevalence of infection with the newly described hepatitis G virus (HGV) in a liver transplant cohort, and to establish the frequency and nature of hepatitis in those with and without HGV infection. A reverse transcriptase-polymerase chain reaction technique was employed to determine viraemia in the patients, and liver biopsies taken at different times after transplantation were assessed histologically. Hepatitis G virus RNA was detected in 47% of the liver transplant recipients investigated. Those positive for HGV had received significantly more blood or blood products than the HGV-negative patients. The frequency of abnormal liver function tests was similar in HGV-positive and HGV-negative recipients. Bile duct epithelial cell damage was more frequently seen in those with HGV viraemia. This study indicates that almost half of the liver transplant recipients in Northern England are positive for HGV, and that infection is associated with exposure to blood and blood products. It appears that, in the immunosuppressed patient, HGV does not cause clinically significant liver disease, at least up to 2 years after transplantation. If HGV infection is associated with hepatitis outside this clinical setting, it is likely that the liver damage is immunopathologically mediated rather than as a result of direct viral cytotoxicity.
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PMID:Hepatitis G virus does not cause significant liver disease after liver transplantation. 949 15

The replication sites of the recently discovered hepatitis G virus (HGV) remain unknown. Using highly strand-specific Tth-based reverse transcriptase PCR, we searched for the presence of viral RNA negative strand in multiple autopsy tissues from four patients with AIDS and in peripheral blood mononuclear cells from six other human immunodeficiency virus-positive patients. Negative-strand HGV RNA was detected in three of four bone marrow samples, in two of two spleen samples, and in one of four liver tissue samples. However, the specific cellular site of replication within the positive tissues was not determined. This study does not support HGV as a primary hepatotropic virus.
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PMID:Detection of hepatitis G virus replication sites by using highly strand-specific Tth-based reverse transcriptase PCR. 952 31

The prevalence of hepatitis G virus (HGV) RNA was compared in a cohort of 89 thalassemic children (age range, 1-16 years) with a history of multiple blood transfusions, recruited from the hematology outpatient clinic at Thailand's Chulalongkorn Hospital and in specimens from 200 blood donors at the Red Cross in Bangkok. 29 specimens (32.6%) from thalassemic children, compared with 10 (5%) from blood donors, demonstrated detectable HGV RNA by reverse transcriptase analysis. 48% of the HGV-RNA-positive thalassemic children had elevated alanine aminotransferase levels, compared with 51.9% of the cohort without detectable HGV RNA; a finding that supports the assumption HGV infection does not cause detectable hepatitis. HGV RNA prevalence was 11.8% among children with 2-10 transfusions, 48.8% with 11-50 transfusions, 21.7% in those with 51-100 transfusions, and 16.7% among those with over 100 transfusions. This pattern suggests that at least some of the children recovered from HGV infection and may have developed immunity to reinfection. The clinical significance of HGV, as well as the apparent immunity acquired against reinfection, merit further investigation.
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PMID:High prevalence of hepatitis G virus infection in multiply transfused children with thalassaemia. 957 Feb 37

This was a retrospective study to evaluate the prevalence and impact of hepatitis G virus (HGV) infection in hepatitis C virus (HCV)-positive drug addicts, according to the serological status of hepatitis B virus (HBV) and human immunodeficiency virus (HIV) coinfection. Two hundred and thirty-five randomly selected intravenous drug addicted patients (147 French, 88 Italian) were studied. All patients were positive for antibodies to HCV (anti-HCV). HGV RNA positivity was measured by reverse transcriptase-polymerase chain reaction (RT-PCR). Comparisons of HCV RNA positivity rate, and biological and histopathological variables, were made between HGV RNA-positive and negative patients, according to their HBV and HIV status. HGV prevalence was around 30% in both French and Italian groups. No clear association between HGV infection and a particular HCV genotype was observed. The rate of HCV RNA positivity did not differ between HGV-positive and HGV-negative patients after stratification for hepatitis B surface antigen (HBsAg) and HIV positivity. Histological severity of the underlying chronic hepatitis did not differ according to the HGV status; however, in HIV-positive HBsAg-negative patients, the hepatitis activity was moderately increased in HGV-positive patients. A striking negative influence of HBsAg positivity on HCV replication was observed in HIV-negative patients; an HCV RNA-positive rate of 25% was found in HBsAg-positive patients vs 86% in HBsAg-negative patients; similar significant results were observed in HIV-positive patients, although to a lesser extent. The underlying chronic hepatitis was significantly more severe in HBsAg-positive than in HBsAg-negative HIV-negative patients. Hence, HGV infection is highly prevalent in anti-HCV positive drug addicts but the co-infection with HCV does not seem to influence HCV replication nor to worsen the underlying chronic hepatitis, in HIV-negative patients at least. Reciprocal influence between HBV, HCV and HIV appears rather complex, HBsAg carriage seeming to exert per se a negative effect on HCV replication, particularly in HIV-negative patients, suggesting that interactions between hepatitis viruses should always be analysed in the light of HIV status.
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PMID:Hepatitis G virus infection in hepatitis C virus-positive patients co-infected or not with hepatitis B virus and/or human immunodeficiency virus. 957 37

We investigated the possible role of hepatitis G virus (HGV or GBV-C) in the aetiology of acute non-A-E hepatitis in Argentina by detecting viral RNA in sera by reverse transcriptase-polymerase chain reaction (RT-PCR) using primers specific for the putative NS3 helicase region of HGV. Sixty two patients with acute hepatitis were included in this study. The absence of hepatitis A-E was confirmed by serological testing, and all patients were negative for HCV RNA and autoimmune markers. All patients denied alcohol intake and the use of hepatotoxic drugs. Their mean age was 35.3 years and 37 were males. HGV RNA was present in 19/62 (30.6%) of the patients with non-A-E acute hepatitis. Among HGV-positive patients, three had parenteral risk factors within 3 months of onset, one was a health care worker, one was sexually promiscuous, one had travelled to the Middle East and 13 (68.4%) had no history of parenteral exposure. Epidemiological, clinical and biochemical features between HGV-positive and negative patients did not achieve statistical significance. Hence, HGV appears to play a role in the pathogenesis of acute viral hepatitis; however, the etiology of a significant number of hepatitis cases remains unclear, suggesting the existence of an additional agent(s). The absence of parenteral exposure in most of the HGV RNA-positive patients in this study shows that routes of community-acquired HGV infection are not yet completely understood.
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PMID:Detection of hepatitis G virus RNA in patients with acute non-A-E hepatitis. 965 68

Hepatitis G virus (HGV) is a flavivirus that can cause acute hepatitis and persistent infection but its role in chronic liver disease or primary liver cancer is unproven. In this study we have examined the prevalence of HGV RNA in the serum of patients with hepatitis C virus (HCV) infection and in patients with cryptogenic chronic liver disease, including non-alcoholic steatohepatitis (NASH), and in patients with HCV-related hepatocellular carcinoma (HCC) and HCC arising in patients with cryptogenic liver disease. One-hundred and thirty patients who were positive for antibody to HCV (anti-HCV), 54 patients with cryptogenic chronic liver disease (including 17 patients with NASH) and 46 patients with hepatitis C-related (n = 27) or cryptogenic liver disease-related HCC (n = 19) were studied. HGV RNA was detected using nested reverse transcriptase-polymerase chain reaction (RT-PCR) and was found in 16.1% of patients with HCV infection. HGV RNA was not detected in any patient with cryptogenic liver disease. In patients with HCC, 7/34 samples were positive for HGV RNA and six out of seven HGV-positive subjects also had HCV infection. Only one patient with HCC in cryptogenic liver disease was positive for HGV RNA. Hence, cryptogenic liver disease in the UK is not caused by HGV/GBVc infection. It seems unlikely that HGV plays a significant role in hepatocarcinogenesis.
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PMID:Hepatitis G infection: role in cryptogenic chronic liver disease and primary liver cell cancer in the UK. Trent Hepatitis C virus Study Group. 965 69

The aims of the present study were to identify characteristics that are more often associated with hepatitis G virus (HGV) coinfection in Australian patients infected with the hepatitis C virus (HCV) and to investigate the effects of HGV on the histological and functional severity of chronic hepatitis C. Serum samples from 209 patients with chronic hepatitis C were tested for HGV-RNA using single-round reverse transcriptase-polymerase chain reaction to primers directed at the NS5 region of the HGV genome. Hepatitis G virus RNA was detected in 40 cases (19%). Hepatitis G virus-coinfected patients tended to be younger and parenteral risks could be identified in all but six. Although country of birth did not differ significantly between the coinfected and HCV-alone groups, HGV-positive patients appeared to be less likely to have originated from Asia. On logistic regression analysis, HCV genotype 3a was found in a significantly higher proportion of patients with HGV coinfection than other genotypes (P < 0.01). Liver histology and response to interferon were similar in the HGV-coinfected and HCV-alone groups and liver-related complications appeared to occur less frequently in patients with both HGV and HCV. On univariate analysis, antipyrine clearance was found to be higher in the coinfected group (P < 0.05), implying better preservation of hepatic metabolic function, but this difference was lost when adjusted for HCV genotype. In conclusion, coinfection with HGV was more commonly associated with HCV genotype 3a, a genotype associated with injection drug use in younger patients. However, the presence of HGV coinfection did not adversely affect liver disease or the response to interferon treatment in patients with chronic hepatitis C.
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PMID:Effects of hepatitis G virus coinfection on severity of hepatitis C: relationship to risk factors and response to interferon treatment. 973 67

Hepatitis G virus (HGV) is a recently discovered RNA virus, which belongs to the Flaviviridae family. Although HGV infection is usually not associated with elevated serum transaminases, some recent studies have reported that HGV infection is found in a significant number of patients with fulminant hepatitis and may play a role in its etiopathogenesis. In this study the prevalence of HGV infection was determined in 500 healthy blood donors and in 24 patients admitted to hospital because of acute liver failure caused by fulminant hepatitis. The presence of HGV RNA was tested in sera, obtained at admission and before any transfusion was given, by a sensitive seminested reverse transcriptase-polymerase chain reaction (RT-PCR) assay specific for detection of the non-structural (NS)5 region. Nine of the 500 blood donors (1.8%) and two of the 24 patients (8.3%) were found to be HGV RNA positive. One patient was co-infected with HCV and was known to be an intravenous (i.v.) drug user. After intensive supporting treatment, this patient recovered completely. The second patient had no serological markers of known viral hepatitis infection, including hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), cytomegalovirus (CMV), Epstein-Barr virus (EBV) and herpes simplex virus (HSV). This patient was successfully transplanted. From both patients, from HGV RNA-positive healthy blood donors and from other patients coinfected with HCV, a part of the HGV NS3 region (nucleotides 4191-4345, EMBL entry U45966) was cloned and sequenced. Sequence comparison revealed that the NS3 region of HGV in patients with fulminant hepatitis contained three nucleotide substitutions as part of the six substitutions described in previous work. These nucleotide substitutions were not found in the tested blood donors or in patients with HCV co-infection. Our findings therefore support the concept of the association of fulminant hepatitis with infection of a specific HGV strain.
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PMID:Hepatitis G virus infection in acute fulminant hepatitis: prevalence of HGV infection and sequence analysis of a specific viral strain. 979 13

The replication site for the GB virus-C/hepatitis G virus (GBV-C/HGV) was investigated by using polymerase chain reaction (PCR)-based assays and in situ hybridisation. A total of 28 patients with consecutive GBV-C/HGV infection were enrolled in this study: Nine patients were being treated with immunosuppressive therapy after liver transplantation, and the remaining 19 patients were not receiving such treatment. GBV-C/HGV RNA was detected by using reverse transcriptase-polymerase chain reaction (RT-PCR) and was quantitated by using competitive RT-PCR in all patients. Positive and negative strands of GBV-C/HGV RNA in liver tissue were detected with in situ hybridisation by using RNA probes that were specific for the GBV-C/HGV genome. Concentrations of GBV-C/HGV RNA in serum were significantly higher (P=0.003) in the nine patients who were receiving immunosuppression (median, 10(7) copy/ml; range, 10(5)-10(7)) than in the 19 patients who were not receiving immunosuppressive therapy (median, 10(4) copy/ml; range, 10(2)-10(7)). In situ hybridisation of GBV-C/ HGV RNA was performed on paraffin-embedded liver tissue that was obtained from six patients with GBV-C/HGV infection. Two of those six patients were receiving immunosuppressive therapy, and four were not. Significant positive signals were observed in the samples from two of the six patients who were infected with GBV-C/HGV, but such signals were not observed in any of the six patients who were without the infection. The two patients with positive signals (both were undergoing immunosuppressive therapy) showed both positive and negative strands of GBV-C/HGV RNA in mononuclear cells that infiltrated into portal areas, but neither of the strands was observed in hepatocytes. Moreover, the GBV-C/HGV replication was analysed in peripheral blood mononuclear cells by using strand-specific PCR (conventional RT-PCR and rTth method). Two of the six patients were positive for negative-strand GBV-C/HGV RNA by using conventional RT-PCR. In conclusion, GBV-C/HGV replication was active under an immunosuppressive state, and it is suggested that GBV-C/HGV replicates in mononuclear cells.
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PMID:Detection of GB virus-C/hepatitis G virus genome in peripheral blood mononuclear cells and liver tissue. 989 94


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