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:2.6.1.2 (alanine aminotransferase)
26,722 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

GB virus-B (GBV-B) causes an acute hepatitis in tamarins characterized by increased alanine transaminase levels that quickly return to normal as the virus is cleared. Phylogenetically, GBV-B is the closest relative to hepatitis C virus (HCV), and thus GBV-B infection of tamarins represents a powerful surrogate model system for the study of HCV. In this study, the course of infection of GBV-B in tamarins was followed using a real-time 5' exonuclease (TaqMan) reverse transcription-PCR assay to determine the level of GBV-B in the serum. Peak viremia levels exceeded 10(9) genome equivalents/ml, followed by viral clearance within 14 to 16 weeks. Rechallenge of animals that had cleared infection resulted in viremia that was limited to 1 week, suggestive of a strong protective immune response. A robust tissue culture system for GBV-B was developed using primary cultures of tamarin hepatocytes. Hepatocytes obtained from a GBV-B-infected animal maintained high levels of cell-associated viral RNA and virion secretion for 42 days of culture. In vitro infection of normal hepatocytes resulted in rapid amplification of cell-associated viral RNA and secretion of up to 10(7) genome equivalents/ml of culture supernatant. In addition, infection could be monitored by immunofluorescence staining for GBV-B nonstructural NS3 protein. This model system overcomes many of the current obstacles to HCV research, including low levels of viral replication, lack of a small primate animal model, and lack of a reproducible tissue culture system.
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PMID:Development of a primary tamarin hepatocyte culture system for GB virus-B: a surrogate model for hepatitis C virus. 1109 Jan 76

GB viruses A and B (GBV-A and GBV-B) are members of the Flaviviridae family and are isolated from tamarins injected with serum from a human hepatitis patient. Along with a related human virus, GB virus C, or alternatively, hepatitis G virus (GBV-C/HGV), the three viruses represent the GB agents. Of the three viruses, GBV-B has been proposed as a potential surrogate model for the study of hepatitis C virus (HCV) infections of humans. GBV-B is phylogenetically most closely related to HCV and causes an acute, self-resolving hepatitis in tamarins as indicated by an increase in alanine aminotransferase and changes in liver histology. Similarities between GBV-B and HCV are found at the nucleotide sequence level with the two viruses sharing 28% amino acid homology over the lengths of their open reading frames. Short regions have even higher levels of homology that are functionally significant as shown by the ability of the GBV-B NS3 protease to cleave recombinant HCV polyprotein substrates. The shared protease substrate specificities suggest that GBV-B may be useful in testing antiviral compounds for activity against HCV. Although there are numerous similarities between GBV-B and HCV, there are important differences in that HCV frequently causes chronic infections in people, whereas GBV-B appears to cause only acute infections. The acute versus chronic course of infection may point to important differences between the two viruses that, along with the numerous similarities, will make GBV-B in tamarins a good surrogate model for HCV.
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PMID:GB virus B as a model for hepatitis C virus. 1140 17

Although hepatitis C virus (HCV) is a major cause of non-A non-B hepatitis, its pathogenic role in fulminant hepatitis remains controversial. A 32-year-old man contracted hepatitis. Serum ALT concentration was reached to 6,970 IU/L, the lowest prothrombin time value was 16% and jaundice and stage II encephalopathy were developed. HCV RNA was detected in this patient by reverse transcription polymerase chain reaction in sera at the acute phase, and it was undetectable during the remission phase when anti-HCV was found. The entire genome of infected HCV was recovered, cloned, and sequenced from this patient, and compared with the clones of six other chronic hepatitis patients. Phylogenetic analysis revealed a clustering around genotype 2a and a deviation from the other 2a chronic hepatitis strains. Calculating the genetic distance in each subgenomic region revealed that the 5'untranslated region (5'UTR), core, nonstructural (NS) 3, and NS5A were severely deviated. Of 20 clones of the hypervariable region (HVR), 17 showed an identical sequence with the others showing a difference of only one amino acid. HCV was isolated from a fulminant hepatitis patient and its entire genome was recovered; a clustering around genotype 2a was observed, but the sequence deviated especially in 5'UTR, core, NS3, and NS5A; and monoclonality of the HVR sequence was found not only in the fulminant hepatitis patient but in a certain percentage of chronic hepatitis patients.
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PMID:Sequence analysis of hepatitis C virus isolated from a fulminant hepatitis patient. 1142 23

The majority of hepatitis C virus (HCV)-infected individuals fail to resolve the infection and become chronically infected despite the presence of HCV-specific CTL responses directed to different HCV-derived peptide antigens. Only a minority of individuals is able to clear the virus by mounting efficient CTL responses early after acute infection, but at present it is not clear whether viral clearance is associated with CTL responses of defined specificity. To elucidate those responses associated with improvement of the disease, we analyzed CTL responses to 16 different HLA-A2-presented, HCV-derived epitopes in 12 chronically infected patients, 14 chronically infected patients treated with interferon-alpha, and in one patient with acute symptomatic disease. We show here that the majority of chronically infected individuals present CTL responses directed to an NS4-derived peptide antigen (amino acids 1789-1797). Treated patients presented stronger HCV-specific CTL responses and therapy-induced changes in CTL target choice. In particular, 13 out of 14 individuals responded to an NS3-derived epitope (amino acids 1073-1081). By longitudinal analysis we show that five individuals responding to IFN-alpha therapy with decreases in alanine aminotransferase levels presented a strong CTL activity directed to the NS3-derived epitope. One patient that spontaneously resolved the infection presented a generally strong CTL activity specific for HCV-derived epitopes with a dominant response to the NS3-derived peptide antigen. This suggests that CTL responses directed to this NS3-derived antigen may be beneficial for the control of HCV infection. Improvement of these responses may represent a therapeutic intervention in chronic HCV infection.
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PMID:Effect of interferon-alpha therapy on epitope-specific cytotoxic T lymphocyte responses in hepatitis C virus-infected individuals. 1175 55

Our objective was to verify the presence of prostaglandin-producing suppressor cells in response to hepatitis C virus antigens in peripheral blood mononuclear cells proliferation. Standard proliferation tests were performed in 31 patients: 20 with chronic hepatitis C after antiviral treatment [7 long-term responders (LTR), 7 relapsers (RR), 6 nonresponders (NR)], 7 with HCV infection with persistently normal aminotransferase levels (PNAL), and 4 with hepatocellular carcinoma. Six antigens were used from the core and NS3 regions. A modified proliferation assay consisting of the addition of indomethacin was also done. Lymphoproliferative responses to the HCV antigens were detectable in 27% (11/41) of test points of LTR, 10% (3/31) of RR, 26% (9/35) of NR, and 18% (7/39) of patients with PNAL. Indomethacin only had effect in PNAL patients, by increasing the frequency of reactivity from 18% (7/39) to 36% (14/39) tests points (P = 0.037); also, in three of these patients (43%) indomethacin strongly modified proliferation to core 31-50 and NS3 1248-1261 antigens, increasing both the frequency and stimulation index from 33% (6/18) to 72% (13/18) (chi2 = 5.43, P = 0.019) and 1.89 +/- 0.43 to 6.18 +/- 4.74 (P = 0.028), respectively. These results suggest that prostaglandin-producing suppressor may play a role in chronic HCV infection by inhibiting cellular immune responses in patients with persistently normal ALT.
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PMID:Evidence for prostaglandin-producing supressor cells in HCV patients with normal ALT. 1191 41

A correlation between the detection of proteins and an activity of the pathological process was analyzed in a study of the content of the C virus hepatitis (CVH) proteins in hepatic cells of patients with chronic C hepatitis (CCH). The expression of CVH proteins in frozen sections of biopsy samples of 69 CCH patients was evaluated by using the immune-histological method involving original monoclonal antibodies (MCA) to 5 CVH proteins. The results of the detection of proteins in patients were compared with an activity and stage of CCH (by using histological tests and a level of alanine aminotransferase--AAT). A set of the CVH proteins were found in the liver of 74% of patients, i.e. core proteins, NS3, NS4A, NS4B and NS5A--in 28, 43, 43, 55 and 58%, respectively. All studied proteins were detected in the cytoplasm of hepatocytes. Proteins were found in the liver more often as compared with the detection rate of CVH RNA in the blood serum (61%). This demonstrates a high sensitivity of the discussed test at detecting the CVH infection. The accumulation of the core protein was shown to correlate with the presence of the replicative form of CVH RNA in the liver and with a higher level of AAT. The quantity of NS5 A-expressing cells correlated directly with a CCH stage. The quantity of NSB- and NS3-positive hepatocytes correlated negatively with an activity of the inflammatory-and-necrotic processes in the liver. Hyper-fermentation was found more often among the antigen-positive patients. The CCH histological activity was proven to be reliably higher at a simultaneous detection of CCH proteins in the liver and of CVH RNA--in the serum.
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PMID:[Analysis of hepatitis C virus proteins in hepatic cells of patients with chronic hepatitis C]. 1260 53

This study was designed to evaluate the seroprevalence of hepatitis G virus (HGV) infection, its impact, and its relationship with other hepatotropic viruses among chronic renal failure patients undergoing hemodialysis at the Lok Nayak Hospital, New Delhi. The study group consisted of 100 consecutive cases of patients with chronic renal failure undergoing hemodialysis and equal healthy controls matched for age and sex. The patients were included on the basis of detailed history, clinical examination, and liver function profile. HGV RNA was detected in serum samples of all patients as well as of healthy controls using nested reverse transcription polymerase chain reaction (RT-PCR). The primers used were derived from the NS3 helicase region of the viral genome. Serological assay was used for screening the viral markers for hepatitis B and C (HbsAg and Anti HCV). A history of blood transfusion was recorded in 65% of the cases. HGV RNA was detected in only six out of 100 (6%) cases of chronic renal failure. The seroprevalence of HCV infection was detected in 27 (27%), while HBV infection was seen in 10 (10%) out of 100 cases. The mixed infection of HGV and HCV was seen in 33.3% (two out of six) of the chronic renal failure cases, while the coinfection between HGV and HBV was not observed. In the 100 cases of healthy controls, HGV RNA was detected in only three (3%) subjects. Serological markers for Anti HCV antibody and HbsAg were positive in only one (1%) and two (2%) of the subjects, respectively. The seroprevalence of HGV infection in chronic renal failure was found to be statistically nonsignificant when compared to that of healthy controls. Also, there was no difference in clinical course and liver function profile of HGV-positive and HGV-negative cases. However, alanine aminotransferase (ALT) was significantly out of range in HCV-positive patients compared with HCV-negative patients. The presence of HGV infection reflected a postparental exposure to blood and blood-contaminated products in hemodialysis patients. It is suggested that HGV infection in cases of chronic renal failure is unlikely to influence the course of the disease and may be considered an innocent bystander.
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PMID:Hepatitis G virus infection in hemodialysis patients from urban Delhi. 1571 40

The role of viral factors in the pathogenesis of chronic hepatitis C is unknown. The objective of the present study was to characterize markers of hepatitis C virus (HCV) infection and replication in liver biopsy specimens obtained from 65 genotype 1-infected subjects, including 31 who were coinfected with human immunodeficiency virus (HIV), and to analyze associations between intrahepatic viral markers and hepatitis C disease severity. The percentages of liver cells harboring HCV genomes (%G) and replicative-intermediate RNAs (%RI) were evaluated using strand-specific in situ hybridization, while HCV core and NS3 antigens were assessed by immunocytochemistry. HIV-positive and HIV-negative subjects had similar mean grades and stages of liver disease and had similar indices of HCV infection and replication in liver, even though coinfected subjects had significantly shorter mean disease duration (P = 0.0003). Multivariate analysis showed that %G was not associated with grade or stage of liver disease (P = 0.5 and 0.4, respectively), while %RI was strongly associated with liver inflammation (P < 0.001), liver fibrosis (P < 0.001), and serum alanine aminotransferase levels (P = 0.01). NS3 antigen (but not core) was more frequently detected in HCV RI-positive versus RI-negative specimens (P = 0.028). These findings demonstrate a link between HCV proliferation and hepatitis C disease severity and suggest similar pathogenic mechanisms in HIV-positive and HIV-negative individuals.
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PMID:Intrahepatic hepatitis C virus replication correlates with chronic hepatitis C disease severity in vivo. 1647 35

A total of 176 hospital patients with chronic hepatitis C (CHC), among them 110 males and 66 females, were examined. The spectrum of antibodies to four hepatitis C virus (HCV) proteins (core, NS3, NS4, NS5) and in 142 patients --IgM antibodies to HCV (anti-HCV IgM) were determined. In 92% of the CHC patients antibodies to core, NS3 and NS4 proteins were simultaneously detected. Differences in the detection of antibodies to HCV in males and females were not statistically reliable. In CHC patients aged up to 20 years anti-NS4 and anti-NS5 were less frequently detected. Among males of different age groups reliable differences in the detection rate of anti-NS5 were registered, while among females of different age groups no such differences were observed. With the increase of age these antibodies were detected somewhat more often. In females over 60 years anti-HCV IgM occurred more often than in males of the same age. The levels of alanine aminotransferase (ALT) were higher in persons with the presence of anti-NS5 and anti-HCV IgM than in persons with their absence. In all groups of CHC patients with biochemical activity and liver cirrhosis the detection rate of anti-HCV IgM was significantly higher than in patients with normal ALT activity. The antibody spectrum with the simultaneous absence of HCV IgM and anti-NS5, while found to contain antibodies to other HCV antigens, was registered significantly less frequently in patients with moderate and high CHC activity and the liver cirrhosis induced by HCV infection.
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PMID:[Antibodies to different virus antigens in patients with chronic hepatitis C]. 1675 1

Hepatitis C virus (HCV) continues to represent the main causative agent of the hepatitis, which leads to chronic transformation of the process in 60-80% individuals. It remains unclear how far cellular expression of HCV proteins in vivo may represent an index of progression of the disease and of proliferative activity in the liver in chronic hepatitis C. Aim of the studies included detection and subcellular localization of three HCV proteins (NS3, NS5A and C) in liver biopsies from adults (n=19) with chronic, long lasting hepatitis C as related to hepatocyte proliferative activity. The immunocytochemical ABC (avidin biotin-peroxidase complex) technique was applied, alone or associated with the ImmunoMax technique. Results of the immunocytochemical tests were compared to histological alterations in liver biopsies, proliferation index and with selected clinical data. A significantly higher expression of NS3 protein was noted, as compared to expressions of NS5A and C proteins. In all the patients, cytoplasmic localization of all proteins dominated over nuclear localization (p0.05). At the level of electron microscopy, protein localization in endoplasmic reticulum (ER) membranes, mitochondria, perinuclear region and/or in hepatocyte cell nucleus was observed. No direct relationships could be demonstrated between expressions of HCV proteins and of Ki-67 antigen. No correlations could also be demonstrated between cellular expression of any HCV protein on one hand and grading or staging, alanine transaminase (ALT), serum level of HCV RNA or alpha-fetoprotein (AFP) on the other. However, positive correlations were disclosed between proliferative activity of hepatocytes on one hand and patient's age, grading and staging on the other. Advanced hepatic fibrosis correlated also with serum levels of AFP. The studies were supplemented with data on subcellular localization of HCV proteins. Moreover, they indicated that in HCV infection grading and staging, proliferative activity of hepatocytes and serum AFP level represent more valuable indices of the disease progress than those provided by cellular expression of three potentially oncogenic HCV proteins in vivo.
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PMID:Intracellular expression of the proliferative marker Ki-67 and viral proteins (NS3, NS5A and C) in chronic, long lasting hepatitis C virus (HCV) infection. 1816 75


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