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)

Amplification of viral nucleic acids from the cerebrospinal fluid (CSF) has considerably improved the diagnosis of several acute, subacute and chronic viral infections of the nervous system. In herpes simplex virus (HSV) encephalitis (HSE) the polymerase chain reaction (PCR) has become the method of choice for the rapid, non invasive diagnosis. Other herpes virus associated diseases which can now be reliably diagnosed are encephalitis, ventriculoencephalitis, polymyeloradiculitis, myelitis and an inflammatory polyradiculoneuropathy caused by cytomegalovirus (CMV), HSV, varicella-zoster virus (VZV) or Epstein-Barr virus (EBV), EBV associated primary B-cell-lymphoma of the brain, acute aseptic meningitis in young adults allied with VZV, and meningoencephalitis with recurrent seizures due to human herpes virus type 6 (HHV-6). In AIDS patients, PCR has helped to differentiate lesions either due to the human immunodeficiency virus (HIV) itself or to opportunistic infections such as progressive multifocal leukoencephalopathy (PML) caused by JC virus (JCV) or CMV related complications. HIV can be detected early in the course of infection in the CSF and the amount of proviral DNA in CSF cells seems to be correlated with the severity and/or progression of neurological signs and symptoms. Acute epidemic aseptic meningitis caused by enterovirus infections can now be reliably diagnosed and typed by reverse transcriptase PCR (RT-PCR). Meningitis cases caused by vaccination with the Jeryl Lynn and Urabe vaccine strain of mumps virus have been identified using RT-PCR and sequencing of the amplified products (amplicon).
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PMID:Clinical implications of nucleic acid amplification methods for the diagnosis of viral infections of the nervous system. 879 10

A simple and sensitive method was developed for the differentiation of the Hoshino vaccine strain from wild strains with a restriction fragment length polymorphism (RFLP) analysis in the part of hemagglutinin-neuraminidase (HN) gene. The virus genome was amplified by using a reverse transcriptase-polymerase chain reaction (RT-PCR) directly from clinical samples. The PCR product of the Hoshino vaccine strain was cleaved into 2 fragments after digestion with Sca I and Afl II. All wild strains showed 2 RFLP profiles, A and B, different from that of vaccine strain. Wild A strains were cut into 2 fragments after digestion with Sca I only, while wild B strains were cleaved neither with Sca I nor Afl II. This molecular approach provides an effective method for differentiation of the Hoshino vaccine strain from wild strains of mumps virus in patients after vaccination.
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PMID:Detection of mumps virus genome directly from clinical samples and a simple method for genetic differentiation of the Hoshino vaccine strain from wild strains of mumps virus. 917 68

A reverse transcriptase nested polymerase chain reaction (PCR) was developed to detect the small hydrophobic (SH) gene of mumps virus (MuV). Phylogenetic analysis was performed on the entire SH gene sequence (318 nucleotides) and the putative SH protein (57 amino acids). At least 4 MuV genotypes were identified in the United Kingdom between 1995 and 1998 by direct sequencing of 26 PCR amplicons from a variety of specimens. Comparison of these and GenBank sequences identified 2 new genotypes in the United Kingdom. The results suggest that, after the introduction of universal mumps vaccination in the United Kingdom in 1988, there appears to have been a switch from a predominant genotype to a heterogeneous group of strains.
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PMID:Genetic heterogeneity of mumps virus in the United Kingdom: identification of two new genotypes. 1043 73

Viral RNAs extracted from fifteen mumps virus isolated from throat swab, saliva, blood, urine or CSF during mumps epidemics between 1997-1998 in Korea were amplified by reverse transcriptase-polymerase chain reaction (RT-PCR) and compared by nucleotide sequencing of the small hydrophobic (SH) gene. The deduced amino acid sequences of the SH gene were aligned with the published sequences of mumps virus isolated in different geographic areas. A comparison of the SH gene of mumps viruses in Korea indicated 96.2-100% and 91.2-100% similarity at the nucleotide and amino acid levels, respectively. Phylogenetic analysis, using the neighbor-joining method, showed that Korean mumps virus strains formed a genetically distinct monophyletic group from previously reported genotypes based on the 315-bp length nucleotide and 57 deduced amino acid sequences of the SH gene, and possibly be designated as a new genotype (I).
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PMID:Phylogenetic analysis of the small hydrophobic (SH) gene of mumps virus in Korea: identification of a new genotype. 1078 4

Previous findings of low levels of reverse transcriptase (RT) activity in chick cell-derived measles and mumps vaccines showed this activity to be associated with virus particles containing RNA of both subgroup E endogenous avian leukosis viruses (ALV-E) and endogenous avian viruses (EAV). These particles originate from chicken embryonic fibroblast (CEF) substrates used for propagating vaccine strains. To better characterize vaccine-associated ALV-E, we examined the endogenous ALV proviruses (ev loci) present in a White Leghorn CEF substrate pool by restriction fragment length polymorphism. Five ev loci were detected, ev-1, ev-3, ev-6, ev-18, andev-19. Both ev-18 and ev-19 can express infectious ALV-E, while ev-1, ev-3, and ev-6 are defective. We analyzed the full-length sequence of ev-1 and identified an adenosine insertion within the pol RT-beta region at position 5026, which results in a truncated RT-beta and integrase. We defined the 1,692-bp deletion in the gag-pol region of ev-3, and we found that in ev-6, sequences from the 5' long terminal repeat to the 5' pol region were absent. Based on the sequences of the ev loci, RT-PCR assays were developed to examine expression of ALV-E particles (EV) in CEF supernatants. Both ev-1- and ev-3-like RNA sequences were identified, as well as two other RNA sequences with intact pol regions, presumably of ev-18 and ev-19 origin. Inoculation of susceptible quail fibroblasts with CEF culture supernatants from both 5-azacytidine-induced and noninduced CEF led to ALV infection, confirming the presence of infectious ALV-E. Our data demonstrate that both defective and nondefective ev loci can be present in CEF vaccine substrates and suggest that both ev classes may contribute to the ALV present in vaccines.
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PMID:Characterization of endogenous avian leukosis viruses in chicken embryonic fibroblast substrates used in production of measles and mumps vaccines. 1126 50

The identification of endogenous avian leukosis virus (ALV) and endogenous avian retrovirus (EAV) in chick cell-derived measles and mumps vaccines in current use has raised concern about transmission of these retroviruses to vaccine recipients. We used serologic and molecular methods to analyze specimens from 206 recipients of measles, mumps, and rubella (MMR) vaccine for evidence of infection with ALV and EAV. A Western blot assay for detecting antibodies to endogenous ALV was developed and validated. All serum samples were negative for antibodies to endogenous ALV by Western blot analysis. Peripheral blood lymphocyte samples from 100 vaccinees were further tested by polymerase chain reaction for both ALV and EAV proviral sequences; all were negative. Matching serum samples were tested by reverse transcriptase polymerase chain reaction for ALV and EAV RNA, and all 100 samples were negative, providing no evidence of viremia. These findings do not indicate the presence of either ALV or EAV infection in MMR vaccine recipients and provide support for current immunization policies.
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PMID:Lack of evidence of endogenous avian leukosis virus and endogenous avian retrovirus transmission to measles, mumps, and rubella vaccine recipients. 1126 96

Live virus vaccines for human use, 29 monovalent vaccines against measles, mumps, rubella or polio, eight polyvalent vaccines against measles-mumps-rubella and one bacterial polyvalent vaccine against Streptococcus pneumoniae, were tested by reverse transcriptase-nested PCR for the presence of petivirus or pestivirus RNA. Twenty-four samples were selected from European manufacturers, ten were from U.S.A. and four from Japan. Five (13.1%) out of 38 tested samples were positive for pestivirus RNA. Three vaccines (rubella and two measles) were from Europe and two (mumps and rubella) from Japan. The 5'-untranslated genomic region of the contaminant pestivirus RNA were amplified by reverse transcription-PCR and sequenced. Analyses based on primary nucleotide sequence homology and on secondary structures, characteristic to genotypes, revealed that the cDNA sequences belonged to bovine viral diarrhea virus (BVDV). A cDNA sequence, detected from one measles sample, belonged to BVDV-1b genotype. Pestiviral cDNA detected from the Japanese mumps and rubella vaccine samples, belonged to the BVDV genotypes 1a and 1c, respectively. Analysis on two cDNA sequences detected from measles and rubella vaccine samples from Europe showed their appurtenance to a new genotype, BVDV-1d. These findings indicate that contamination by animal pestivirus may occur in biological products for human use.
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PMID:Genotypes of pestivirus RNA detected in live virus vaccines for human use. 1150 99

All currently licensed yellow fever (YF) vaccines are propagated in chicken embryos. Recent studies of chick cell-derived measles and mumps vaccines show evidence of two types of retrovirus particles, the endogenous avian retrovirus (EAV) and the endogenous avian leukosis virus (ALV-E), which originate from the chicken embryonic fibroblast substrates. In this study, we investigated substrate-derived avian retrovirus contamination in YF vaccines currently produced by three manufacturers (YF-vax [Connaught Laboratories], Stamaril [Aventis], and YF-FIOCRUZ [FIOCRUZ-Bio-Manguinhos]). Testing for reverse transcriptase (RT) activity was not possible because of assay inhibition. However, Western blot analysis of virus pellets with anti-ALV RT antiserum detected three distinct RT proteins in all vaccines, indicating that more than one source is responsible for the RTs present in the vaccines. PCR analysis of both chicken substrate DNA and particle-associated RNA from the YF vaccines showed no evidence of the long terminal repeat sequences of exogenous ALV subgroups A to D in any of the vaccines. In contrast, both ALV-E and EAV particle-associated RNA were detected at equivalent titers in each vaccine by RT-PCR. Quantitative real-time RT-PCR revealed 61,600, 348,000, and 1,665,000 ALV-E RNA copies per dose of Stamaril, YF-FIOCRUZ, and YF-vax vaccines, respectively. ev locus-specific PCR testing of the vaccine-associated chicken substrate DNA was positive both for the nondefective ev-12 locus in two vaccines and for the defective ev-1 locus in all three vaccines. Both intact and ev-1 pol sequences were also identified in the particle-associated RNA. To investigate the risks of transmission, serum samples from 43 YF vaccine recipients were studied. None of the samples were seropositive by an ALV-E-based Western blot assay or had detectable EAV or ALV-E RNA sequences by RT-PCR. YF vaccines produced by the three manufacturers all have particles containing EAV genomes and various levels of defective or nondefective ALV-E sequences. The absence of evidence of infection with ALV-E or EAV in 43 YF vaccine recipients suggests low risks for transmission of these viruses, further supporting the safety of these vaccines.
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PMID:Identification and characterization of avian retroviruses in chicken embryo-derived yellow fever vaccines: investigation of transmission to vaccine recipients. 1250 26

A review of mumps outbreaks among both non-vaccinated and vaccinated children and young adults in the East Bohemian region in 2003-2005 is presented. A significant increase in mumps cases was observed over this period. The clinical diagnosis was confirmed serologically by ELISA detection of IgM antibodies and/or IgG seroconversion and increased levels of IgG antibodies. A reverse transcriptase nested PCR was introduced for direct detection of mumps virus RNA from clinical specimens (nasopharyngeal secretion, saliva, CSF and serum). The isolated RNA will be stored for further analysis and mumps virus genotyping attempts, helpful in tracing the virus circulation in the East Bohemia region. Possible causes of the recent significant increase in mumps cases among the vaccinated population in the Czech Republic are discussed.
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PMID:[Mumps--a reemerging infection? The current incidence of mumps in the East Bohemian region in the Czech Republic]. 1735 87

It has been demonstrated that the detection of enteroviruses and mumps virus nucleic acid in cerebrospinal fluid (CSF) specimens improves the management of the patients with aseptic meningitis. To determine the effect of overnight enrichment of mumps and enteroviruses in CSF samples on cell culture for increasing the sensitivity of viral detection, we developed a multiplex reverse transcriptase-polymerase chain reaction (RT-PCR). CSFs were collected from 100 patients younger than 7 years. The samples were tested for the presence of enteroviruses and mumps virus by multiplex RT-PCR method. Negative samples in Multiplex RT-PCR were enriched for viral template RNAs by overnight culture of CSF samples on cells and followed by the optimized Multiplex RT-PCR. Overall, 35% of the CSF samples were positive for enteroviruses, whereas only 1% of CSF samples were positive for both viruses. After enriching in cell culture, 34% of the negative samples showed a positive polymerase chain reaction band for enteroviruses, and a 3% increase was observed for both viruses. The results showed that enrichment of viral template RNAs in cell culture can increase the sensitivity of the multiplex RT-PCR assay and provide a rapid and sensitive method for detection of viral infections.
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PMID:Enrichment of cerebrospinal fluid samples on cell culture for enhancement of sensitivity of mumps and enterovirus detection by multiplex RT-PCR. 1808 20


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