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)

We tested for infection with hepatitis C virus (HCV) in 58 patients affected by humoral immunodeficiencies: 43 common variable immunodeficiency (CVI), two hyper IgM syndrome (HIM), two IgG subclass deficiency, four ataxia-telangiectasia (AT), and seven X-linked agammaglobulinaemia (XLA). While the assessment of serum specific HCV antibodies in some of these patients was not informative because of the impairment in specific antibody production, the reverse transcriptase polymerase chain reaction (RT-PCR) assay used to detect serum HCV RNA was a useful method for diagnosing infection. We found that 38% of late onset hypogammaglobulinaemic patients (CVI, HIM or IgG subclass deficiency) had evidence of HCV infection. HCV infection was not detectable in patients with XLA or AT. The majority of our patients had persistent viraemia, and those who underwent liver biopsy showed histological findings of chronic hepatitis. Moreover, we could demonstrate in vitro that eight of 18 HCV-infected patients were actively producing anti-HCV antibodies, despite their impaired antibody production. The high rate of HCV infection in hypogammaglobulinaemic patients could be related to several nosocomial routes of transmission, including intravenous immune globulin administration. Despite the persistent viremia only two patients had cirrhosis and none had hepatocarcinoma.
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PMID:HCV infection in patients with primary defects of immunoglobulin production. 755 76

A nonselective ex vivo assay was used to directly detect and quantify zidovudine (AZT)-resistant human immunodeficiency virus type 1 (HIV-1) in the blood of treated and untreated patients. In contrast to previous reports, drug-resistant virus was detected in peripheral blood mononuclear cells of a few of the patients who had never received AZT. The AZT resistance of HIV-1 isolates from one untreated individual was confirmed by further susceptibility studies in vitro and by the finding of a characteristic mutation (Lys-->Arg at codon 70) in the reverse transcriptase. In patients who were clinically stable while on AZT, HIV-1 titers in plasma and mononuclear cells were generally low but resistant viruses already predominated. In those individuals who were deteriorating despite AZT administration, high levels of viremia were observed, and the resistance phenotype was nearly universal. These findings serve to emphasize the magnitude of the AZT-resistance problem in patients on drug treatment.
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PMID:Quantitation of zidovudine-resistant human immunodeficiency virus type 1 in the blood of treated and untreated patients. 767 40

Chimpanzees are currently the only nonhuman animal model for reproducible propagation of hepatitis C virus (HCV). A chimeric mouse model was used for the induction of hepatitis C viremia, using BNX (beige/nude/X-linked immunodeficient) mice preconditioned by total body irradiation and reconstituted with SCID mouse bone marrow cells. HCV-infected liver fragments from patients with HCV RNA-positive sera were transplanted under the kidney capsule of the chimeric mice. HCV-specific RNA sequences were detected by reverse transcriptase nested polymerase chain reaction (RT-PCR) in serum of approximately 50% of grafted animals. In addition, normal liver specimens were incubated with HCV serum and transplanted into chimeric mice, leading to viremia in approximately 25% of animals. Sequential histologic evaluation of the liver implants, from day 2 to week 14 after transplantation, revealed loss of lobular architecture within the implants. However, viremia persisted for 10-50 days after transplantation. These results offer a new HCV model.
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PMID:Hepatitis C virus viremia in SCID-->BNX mouse chimera. 779 23

Quantitation of human immunodeficiency virus type 1 (HIV-1) RNA in the plasma of seropositive individuals was performed by using an external control assay with techniques to standardize and control each measurement. Rigorous study of the variability of the assay showed that the median intraassay reproducibility was log10 0.15 RNA copies per ml of plasma, while the median interassay reproducibility on replicate plasma samples was log10 0.25 copies perml. Specimen stability studies showed reproducible recovery of RNA from plasma stored at -70 degrees C for up to 12 months. In clinically stable patients who were either untreated or taking zidovudine, the average week-to-week variation in plasma RNA levels, measured in real time, was log10 0.30 RNA copies per ml. In contrast, patients either initiating or changing antiretroviral therapy showed a fall of log10 0.8 to log10 2.0 copies per ml in plasma RNA levels. Overall, 105 of 110 (96%) HIV-1-seropositive individuals with CD4 counts of 36 to 868 cells per mm3 had quantifiable HIV-1 RNA over a range of log10 2.70 to log10 6.23 RNA copies per ml, including 81% (13 of 16) of the individuals with greater than 500 CD4 cells per mm3. Accurate and reproducible quantitation of plasma viremia in real time by reverse transcriptase polymerase chain reaction, particularly in asymptomatic HIV-1-infected individuals with high CD4 counts, provides a basis for the use of this virologic measure to monitor the short- and long-term effects of early intervention therapeutic strategies on viral burden.
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PMID:Biological variation and quality control of plasma human immunodeficiency virus type 1 RNA quantitation by reverse transcriptase polymerase chain reaction. 790 17

Virtually full protection against hepatitis E and partial or complete protection against infection with hepatitis E virus (HEV) were achieved in passively or actively immunized cynomolgus monkeys. Hepatitis, viremia, and shedding of the virus in feces were detected in all nonimmunized animals that were challenged with HEV. HEV titers detected by reverse transcriptase PCR were higher in feces than in serum of nonimmunized animals. Anti-HEV antibody titers at the time of challenge ranged between 1:40 and 1:200 in animals passively immunized with convalescent plasma from a cynomolgus monkey previously infected with HEV and between 1:100 and 1:10,000 in animals actively immunized with a recombinant 55-kDa open reading frame 2 protein. The estimated 50% protective titer of passively acquired anti-HEV antibodies was 1:40. Although only one of four passively immunized animals showed histopathologic evidence of hepatitis, all four were infected after challenge; however, the titers of HEV in serum and feces were lower in the passively immunized animals than in the nonimmunized group. The actively immunized animals developed neither hepatitis nor viremia when challenged with HEV and virus was either not detected or was present in low titer in feces. The protective response was a function of the ELISA anti-HEV antibody titer at the time of challenge and the immunization schedule.
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PMID:Successful passive and active immunization of cynomolgus monkeys against hepatitis E. 793 61

Coxsackievirus B3 (CVB3)-induced myocarditis was studied in euthymic (nu/+) and athymic (nu/nu) C3H/HeN (H-2k) mice. Mice were inoculated intraperitoneally with 10(6) p.f.u. of CVB3 (Nancy strain) and sacrificed at intervals up to 92 days post-inoculation (p.i.). Viraemia peaked at day 2 to 3 p.i. and ceased at day 5 to 7 p.i. in a synchronized manner in both sets of mice. Very few infectious particles were detected in the blood of nu/nu mice after day 14 p.i. In nu/nu mice, CVB3 persisted in myocardial tissue with constant titres between 2.7 +/- 1.9 x 10(4) and 7.6 +/- 5.2 x 10(4) p.f.u./mg from day 3 to 92 p.i., which were comparable to those of nu/+ mice in the acute phase. In nu/+ mice, the virus was recovered from all animals examined by day 11 p.i. and from three out of 13 mice between days 14 and 21 p.i., yet no virus was recovered from nu/+ mice at day 42 p.i. In nu/nu mice, sense and antisense RNA for CVB3 was detected in the myocardial tissue up to day 42 p.i. by in situ hybridization and up to day 92 p.i. by reverse transcriptase-PCR. Neither sense nor antisense RNA was detected after day 21 p.i. in nu/+ mice with the same techniques. Myocardial tissue damage was analysed morphologically. At day 92 p.i., the area of myocardial injury peaked at 23% of the section in nu/nu mice. In contrast, less than 0.6% of tissue sections contained lesions in nu/+ mice. A neutralizing antibody response to CVB3 was observed in both nu/nu and nu/+ mice. The mean titre of neutralizing antibody was significantly higher at day 21 p.i. in nu/+ mice, but similar at day 42 p.i. with nu/nu and nu/+ mice. Perforin-producing natural killer-like cells, which are considered to play an important role in causing acute myocarditic lesions in immunocompetent mice, were found in the lesions of nu/nu mice persistently infected with CVB3. Prolonged tumour necrosis factor-alpha mRNA synthesis detected in nu/nu mice appears to reflect the continuous activation of macrophages, which extend phagocytic reactions to virus-infected myocytes. These immunological results suggested that the host immune response devoid of antigen-specific T cell function is not sufficient to terminate CVB3 infection in nu/nu mice. Also, it appears that competent cellular immunity, on the whole, plays a role in curing rather than in aggravating myocarditis in nu+mice.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Persistence of replicating coxsackievirus B3 in the athymic murine heart is associated with development of myocarditic lesions. 796 2

An experimental study was performed to investigate the efficacy of irradiating HIV-contaminated allografts. Irradiation was achieved using an accelerator delivering 6.3 MeV electrons, and the viral strain was HIV-1/LAV-1. At an activity equivalent to 600.000 counts of reverse transcriptase activity per minute and per millilitre, irradiation permitted total inactivation of HIV. In the light of present data concerning plasma viremia in HIV-infected patients, this experiment suggested that irradiation minimizes as far as possible the risk of transmitting HIV infection through bone transplantation from a seronegative, contaminant donor. However, in view of the relative imprecision of viral sensitivity curves, irradiation does not authorize bone transplantation from a seropositive patient, even though the bone has been irradiated.
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PMID:[Bone sterilization by radiation and the HIV virus]. 806 95

A method for quantitating human immunodeficiency virus type 1 plasma viremia may be useful in monitoring disease progression and the responsiveness of patients to a therapeutic regimen or vaccine. A quantitative assay for viral RNA in plasma or sera that differs in several aspects from those reported previously was developed. First, whereas conventional reverse transcriptase-PCR assays involve a two-step process and use two enzymes, the method described uses a single enzyme, rTth DNA polymerase, for both reverse transcription and PCR. The reactions are carried out in a single tube and with a single buffer solution with uninterrupted thermal cycling. Second, uracil-N-glycosylase and dUTP are incorporated into the reaction mixtures to ensure that any carryover of DNA from previous amplifications will not compromise quantitation. Third, a quantitation standard is incorporated into each reaction mixture so that differences in amplification efficiency caused by sample interferents, variability in reaction conditions, or thermal cycling can be normalized. To ensure comparable amplification efficiency, the quantitation standard has the same primer-binding regions as the human immunodeficiency virus type 1 target and generates an amplified product of the same size and base composition. The probe-binding region was replaced with a sequence that can be detected separately. Fourth, a colorimetric detection format was modified to provide at least a four-log-unit dynamic range. The quantitative assay requires only a single amplification of the sample and can be completed in less than 8 h. The procedure was used on archival samples to demonstrate the viremic spike in acute infection and the suppressed levels of circulating virus following seroconversion.
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PMID:Rapid and simple PCR assay for quantitation of human immunodeficiency virus type 1 RNA in plasma: application to acute retroviral infection. 815 Sep 37

Polymerase chain reaction (PCR) involves alternate denaturing and re-annealing of DNA in test samples in the presence of appropriate oligonucleotide primers complementary to opposite strands of the target DNA together with a heat-stable DNA polymerase, Mg2+ and the four nucleotide triphosphates. DNA target segments can be 'amplified' ten-millionfold by 25-35 such cycles. Even greater amplification (approximately 10(12)-fold) with enhanced specificity can be obtained by a second set of amplification cycles using a further pair of 'nested' primers sited within the DNA sequence defined by the original primers. PCR can be applied to the study of the whole range of transfusion-transmitted infections, both plasma and cell associated; RNA viruses can be analyzed if a DNA copy is made from the viral RNA by treatment with reverse transcriptase. In a transfusion context, the retroviruses (HIV-1, HIV-2, HTLV-I, HTLV-II), HCV and HBV have been the viruses most intensively subjected to PCR analysis. The advantages of PCR in this context include its ability to detect virus during the 'window period' or seronegative stages of infections and its value as a marker for viraemia and for the detection of viruses in products made from large pools of plasma. True immunity may also be differentiated from persistent infection in the presence of antibody. Similarly, PCR can overcome problems of diagnosis of acute infection caused by the presence of passively transferred antibody. Detailed strain differentiation is also possible by PCR, in conjunction with sequencing or with the aid of restriction endonucleases.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Polymerase chain reaction and transfusion microbiology. 838 93

Experimental intravenous challenge of 8-week-old kittens with the feline immunodeficiency virus Maryland isolate (FIV-MD) was investigated for its ability to infect the central nervous system (CNS) and induce neurologic abnormalities. Six cats were inoculated with 1,000 TCID50 units of FIV-MD isolate, with six age-matched cats serving as uninfected controls. Clinical and immunological evaluation documented that challenged cats developed immunodeficiency and growth delay. Neurologic examination revealed an abnormal stereotypic motor behavior consisting of repetitive, compulsive roaming that developed as early as 4 weeks postinfection (PI) and persisted throughout the 16-month study in three cats. Serial neuroelectrodiagnostic evaluation revealed persistent abnormal electroencephalographic recordings in three infected cats. Serial evoked potential (EP) recordings at 3, 8, and 12 months PI demonstrated significantly prolonged interpeak latencies III-V at 3 months PI and I-III at 12 months PI for brainstem EP recordings. Alterations of visual EPs were detected only at the 3-month time period. Retinocortical time, however, was significantly different from that in control cats at 3 and 12 months PI. Magnetic resonance imaging evaluation of FIV-MD-infected cats at 12 months PI revealed cortical atrophy, mild ventricular enlargement, and discrete white matter lesions. At 16 months PI, however, histopathological examination of brain tissue indicated only mild lesions limited to satellitosis and perivascular lymphocytic infiltrates. Virus was detected in the CNS by reverse transcriptase, immunofluorescence, and antigen capture. Evaluation of the cerebrospinal fluid revealed intrathecal anti-FIV-MD antibody despite lack of detectable viremia in five challenged cats. Collectively, these findings demonstrate the induction of virus-associated neurologic disease following parenteral FIV challenge in conjunction with an immunodeficiency state. The nature of the nervous system infection is analogous to HIV-1 pediatric encephalopathy.
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PMID:AIDS-associated encephalopathy with experimental feline immunodeficiency virus infection. 838 49


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