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)

A quantitative reverse transcriptase PCR assay with automated detection by nonradioactive hybridization was developed for the determination of human immunodeficiency virus (HIV) type 1 RNA levels. This assay is based on the use of an external standard curve with an internal standard. The accuracy of quantification was verified by comparison with reference commercial tests, the Chiron branched-DNA and Roche AMPLICOR HIV MONITOR assays. This assay was able to quantify viremia in patients with CD4 cell numbers below and above 500/mm3 and to quantify some HIV strains which could not be titrated by the MONITOR assay.
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PMID:Development of a reverse transcriptase PCR-enzyme-linked immunosorbent assay for quantification of human immunodeficiency virus type 1 RNA in plasma: comparison with commercial quantitative assays. 911 17

A nonradioactive reverse transcriptase (RT) assay was used to measure RT activity in serum during the viremia peak associated with primary infection and for measuring the generation and maintenance of RT activity-blocking antibody (RTb-ab) titers during and after seroconversion in SIV-infected macaques. The RT assay was compared to an antigen capture immunoassay designed for HIV-2/SIVsm and was found to be approximately 40 times more sensitive in detecting SIVsm in serum from infected macaques. The RT assay detected RT activity in serum corresponding to levels from 3 pg/ml. Earliest detection of viral replication using the RT assay was on day 6-8, with a peak at day 10 (up to 8000 pg/ml). The earliest detection of RTb-ab was seen on day 17-23, with established RTb-ab titers by day 29, followed by increasing titers of 15,000-120,000 by day 62-77. The usefulness of RT and RTb-ab for monitoring the course of SIV infection in monkey models is discussed.
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PMID:Reverse transcriptase and corresponding activity-blocking antibody for monitoring SIVsm infection in macaques. 913 78

A reverse transcriptase-polymerase chain reaction (RT-PCR) method was developed as a rapid diagnostic test of dengue viremia. To detect dengue viruses in serum or plasma specimens, a pair of universal primers was designed for use in the RT-PCR. Using these primers, the 3'-noncoding region of dengue virus types 1, 2, 3, and 4 could be amplified, but not those of other flaviviruses, such as West Nile virus, Japanese encephalitis virus, and yellow fever virus, or the alphavirus Sindbis virus. The sensitivity of the RT-PCR assay was similar to that of a quantitative fluorescent focus assay of dengue viruses in cell culture. Combining a silica method for RNA isolation and RT-PCR dengue virus could be detected in a 6-hr assay. In a preliminary study using this method, we detected dengue virus in 38 of 39 plasma specimens from which dengue virus had been isolated by mosquito inoculation. We then applied this method for detecting dengue viremia to 117 plasma samples from 62 children with acute febrile illnesses in a dengue-endemic area. We detected dengue viremia in 19 of 20 samples obtained on the day of presentation, which had been confirmed as acute dengue infection by mosquito inoculation and antibody responses. The overall sensitivity of this method was 91.4% (32 of 35; 95% confidence interval [CI] = 82.2-100%). The results from testing plasma samples from febrile nondengue patients showed a specificity of 95.4% (42 of 44; 95% CI = 89.3-100%).
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PMID:Rapid diagnosis of dengue viremia by reverse transcriptase-polymerase chain reaction using 3'-noncoding region universal primers. 915 52

Chimpanzees were challenged with HIV-1IIIB while receiving a short regimen of nevirapine (Viramune), a nonnucleoside inhibitor of HIV-1 reverse transcriptase. The untreated, control chimpanzee developed an infection characterized by seroconversion, viremia in peripheral blood mononuclear cells (PBMCs), and plasma positive for viral RNA. In contrast, the three nevirapine-treated chimpanzees remained negative for all viral markers with the exception of nested polymerase chain reaction (PCR) analysis of PBMCs for viral DNA. Although PBMCs from the three nevirapine-treated chimpanzees tested intermittently positive for viral DNA, this PCR signal disappeared and remained negative for the final five months of the study. These data indicate that orally administered nevirapine provided protection from HIV-1 infection in the chimpanzee model.
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PMID:Prophylaxis against HIV-1 infection in chimpanzees by nevirapine, a nonnucleoside inhibitor of reverse transcriptase. 917 94

The hepatitis G virus (HGV) has recently been identified as a new member of the Flaviviridae family. Infection by this virus is thought to be associated with blood borne hepatitis. In this study, the presence of HCV- and HGV-RNAs in serum or plasma (175 patients) and in peripheral blood mononuclear cells (PBMC) (133 patients) was investigated in patients with clotting disorders using a sensitive reverse transcriptase polymerase chain reaction (RT-PCR). HGV-RNA was detected in serum of 26 patients (14.8%). In apparently healthy blood donors, serum HGV-RNA was detected in 4 of 358 individuals investigated (1.12%). Ninety two percent of the 26 serum HGV-RNA positive patients had coinfection with the hepatitis C virus (HCV), especially with HCV genotype 1b, the most common genotype in Belgium. Of these coinfected patients, 15 (62.5%) showed elevated serum ALT levels. Two patients who were solely infected with HGV had normal serum ALT.HGV-RNA in PBMC was found in 18 patients, of whom 3 were negative for serum HGV-RNA. As in case of HCV, HGV-RNA in PBMC is preferentially sensitive to interferon treatment. Nevertheless, rapid reappearance of HGV-RNA in PBMC was observed after cessation of treatment. In one patient, persistent serum ALT elevation seems to be associated with continued HGV viremia, despite the disappearance of serum HCV-RNA.
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PMID:Hepatitis G viral RNA in serum and in peripheral blood mononuclear cells and its relation to HCV-RNA in patients with clotting disorders. 918 94

It has become clear that the acquired immunodeficiency syndrome follows continuous replication of the human immunodeficiency virus (HIV) and a decrease in immune capability, most obviously a decline in the number of CD4 lymphocytes. An understanding of key elements in the infectious life cycle of HIV has led to the development of potent antiretroviral drugs selectively targeting unique reverse transcriptase and protease enzymes of the virus. Completed clinical trials have shown that antiretroviral therapy for HIV infection, begun early, reduces viral replication and reverses the decline in CD4 lymphocyte numbers. Recent studies of combination therapies have shown that decreases in plasma HIV viremia to low levels and sustained increases in CD4 cell numbers are associated with longer survival. Potent combination regimens including protease inhibitors and non-nucleoside reverse transcriptase inhibitors suppress detectable viral replication and have demonstrated clinical benefits in patients with advanced disease. Progress in antiretroviral therapy and methods to monitor responses to treatment are providing new hope in the treatment of HIV infection.
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PMID:Antiretroviral therapy for human immunodeficiency virus infection in 1997. 921 34

Although hepatitis G virus infection (HGV) is usually asymptomatic, it has been associated with mild hepatic injury. Whether hepatitis G co-infection alters the natural history of other viral hepatitis infections remains to be determined. In the present study, we investigated whether hepatitis G impacts on the time to recurrent hepatitis or on the time to progression to fibrosis in hepatitis C-infected patients who undergo liver transplantation. Forty-five liver transplantation recipients with persistent hepatitis C viremia by polymerase chain reaction (PCR) were evaluated. Stored sera obtained before and after liver transplantation was tested for HGV RNA by reverse transcriptase (RT)-PCR using primers to the 5' region of the HGV genome. A median of eight serial liver biopsy specimens were reviewed per patient. The prevalence of HGV co-infection was 21% before transplantation and 22% following transplantation. During a median follow-up of 29 months, 78% (35/45) of patients with hepatitis C viremia developed histological features of recurrent hepatitis. Fifty-one percent (23/45) progressed to fibrous portal expansion and 16% (7/45) developed bridging fibrosis. Comparisons of patients with and without hepatitis G co-infection following transplantation showed no significant difference in time to recurrent hepatitis, fibrous portal expansion, bridging fibrosis, or of allograft or patient survival. In conclusion, hepatitis G co-infection does not seem to impact on the time to recurrent hepatitis C or progression of hepatitis C-related histological injury after liver transplantation.
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PMID:Hepatitis G virus co-infection does not alter the course of recurrent hepatitis C virus infection in liver transplantation recipients. 925 55

Hepatitis C virus (HCV) has been recognized as the cause of thrombocytopenia occurring in patients with chronic hepatitis C, possibly through autoimmune mechanisms. A patient is described with B cell chronic lymphocytic leukaemia, presenting with a marked leuko-thrombocytopenia and an associated mild haemolysis secondary to HCV infection, in the absence of clinical and biochemical signs of hepatitis. Anti-HCV antibodies were detected in the serum both by ELISA and RIBA but not 2 months before the onset of cytopenia. The presence of HCV RNA was documented both in the peripheral blood mononuclear cells and in the bone marrow by reverse transcriptase polymerase chain reaction of the 5' untranslated region of the viral genome. Of interest, HCV RNA was also found in the serum, showing that viraemia was associated with the presence of circulating anti-HCV antibodies. HCV genotyping, performed by PCR amplification of the core region, revealed the presence of an unclassifiable genotype. The hypothetical mechanisms leading to HCV-induced cytopenia in this patient are briefly discussed. Treatment with corticosteroids was effective in controlling blood cell counts, without increasing viraemia and deterioration of liver disease. HCV infection should be considered in the differential diagnosis of possible causes of cytopenia, mainly in immunosuppressed patients, even in absence of clinical and biochemical signs of hepatitis.
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PMID:Hepatitis C virus-induced leuko-thrombocytopenia and haemolysis. 933 31

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


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