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)

For this retrospective study, infectious bursal disease virus (IBDV) was detected in 134 bursal samples that originated from flocks with conditions such as airsacculitis, tracheitis, pneumonia, septicaemia, inclusion body hepatitis, coccidiosis, and/or a history of production problems without overt clinical symptoms. Samples were from seven Canadian provinces: Ontario, Quebec, Manitoba, British Columbia, Nova Scotia, Alberta, and Newfoundland and Labrador. Viral RNA was identified in bursae with moderate to severe and acute to chronic bursal damage. The ages of the flocks from which samples were collected ranged from 3 to 63 days. Following reverse transcriptase-polymerase chain reaction the nucleotide sequence of the VP2 hypervariable region was determined and compared with sequences available in GenBank. The most common Canadian IBDV field strains were North-American variant viruses. Forty-four viruses were highly related (97.5% to 100.0%) to the US IBDV strain NC171. Moreover, 16 field viruses whose VP2 sequences were 99.2% to 100% identical to the South African 05SA8 IBDV strain appeared closely related to the NC171 group. Delaware E-related field viruses, 98.3% to 100.0% identical to the prototype virus, were identified in 33 samples. Thirty-four Canadian IBDVs showed the highest identity, 94.2% to 98.3%, to US IBDV strain 586. Five samples contained vaccine-related viruses, while two field strains showed the best match to Del A (United States) and IBDV strains SP_04_02 (Spain). Very virulent IBDVs were not detected in Canada.
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PMID:Genotyping of Canadian field strains of infectious bursal disease virus. 1789 69

Bursal samples collected from different field outbreaks in commercially reared chicken flocks from India that were suspected of very virulent (vv) infectious bursal disease (vvIBD) were tested. Two vaccine strains that are commonly being used in India also were included to ascertain their relatedness with the field isolates. When tested with real-time reverse transcriptase-polymerase chain reaction (RT-PCR), 14 of the 15 samples were found to be positive for vvIBD virus (vvIBDV) genetic sequences as determined by the vv232 and vv256 vvIBDV-specific probes. A melting temperature of 50 C and above was characteristic of vvIBDV strains. The vaccine strain infectious bursal disease intermediate (IBDI)-plus (IBDI+) had a higher melting temperature compared with IBDI, suggesting more relatedness to the vvIBDV strains. The real-time RT-PCR technique can be a useful tool in differentiating classic and vvIBDV strains and thereby assist in adopting more effective control strategies. Sequencing of the VP2 hypervariable region of these isolates further confirmed the results of real-time RT-PCR. All the suspected vvIBDV samples were found to share unique amino acid substitutions at positions 222 A, 256 I, 294 I, and 299 S characteristic of the very virulent strains. More sequence differences occurred at the nucleotide level among the vvIBDVs. They shared exactly the same amino acid sequence among themselves and also with the Bangladesh isolate BD-3-99 and some of the Nigerian isolates. They differed by one amino acid from earlier published Indian, Asian, and European vvIBDV VP2 sequences. The nucleotide sequence of IBDI+ vaccine showed more similarities with vvIBDV sequences; hence, it may be of more value in the control of these very virulent strains.
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PMID:Real-time reverse transcriptase-polymerase chain reaction detection and sequence analysis of the VP2 hypervariable region of Indian very virulent infectious bursal disease isolates. 1799 37

Twenty bursal samples were obtained from four infectious bursal disease virus (IBDV)-vaccinated layer flocks experiencing problems with immune suppression that was thought to be infectious bursal disease. All the samples were found to be positive for IBDV by reverse transcriptase polymerase chain reaction (RT-PCR). Restriction fragment length polymorphism analysis of the samples identified them as classic molecular group 3 and group 4 viruses. Two samples from each of the four flocks were sequenced, and within a flock, these sequences were identical; however, between flocks, some differences were observed. One virus from each of the four flocks was selected for further analysis. The VP2 hypervariable sequence region of samples GA-1, H-30, and CS-2-35 had nucleotide and amino acid similarities with the D78 and Vi Bursa G classic vaccines that were used in those flocks. The sequence of HPR-2 was similar to the Bursa Vac 4 vaccine used in that flock and the STC virulent classic IBDV strain. The deduced amino acid sequence of these isolates revealed that all the isolates had proline at position 222, which is characteristic of U.S. classic viruses. The phylogenetic analysis of these isolates on the basis of the VP2 hypervariable amino acid sequence clustered GA-1, H-30, and CS-2-35 with the D78 vaccine and HPR-2 with STC. The pathogenicity of these isolates was tested in specific-pathogen-free chickens. Bursa-body weight (B-BW) ratios and histopathologic lesion scores in the bursa were determined. Gross lesions were observed in the bursa, and the B-BW ratios of the birds infected with all four wild-type viruses were significantly different compared with the D78 vaccine and uninoculated control groups. Histopathology of the bursa from groups infected with GA-1, H-30, CS-2-35, and HPR-2 showed different degrees of follicular depletion and necrosis. A very slight lymphoid depletion was observed in the D78-infected group at 5 days postinoculation, and no microscopic lesions were observed in this group at 8 days postinoculation or at any time in the uninoculated control group. The bursa collected from the field virus and D78-infected birds at necropsy revealed the presence of IBDV via RT-PCR, and the VP-2 hypervariable nucleotide sequences of the GA-1, H-30, CS-2-35, HPR-2, and D78 samples were identical to the original viral isolates and vaccine, respectively.
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PMID:Characterization of infectious bursal disease viruses from four layer flocks in the United States. 1825 92

This study was conducted to characterize nine infectious bursal disease virus (IBDV) isolates from Iran. A reverse transcriptase-polymerase chain reaction (RT-PCR) procedure was used to amplify a 743-bp fragment of the VP2 gene hypervariable region from IBDV field isolates. Amplified VP2 fragments of the nine IBDV isolates were sequenced and compared with published sequences of IBDV strains from Iran and around the world, and their phylogenetic relationships were analyzed. Three isolates demonstrated close relation to classical attenuated strains of IBDVs, and six isolates showed sequences common in European and Asian strains of very virulent IBDVs (vvIBDVs). Four nucleotide changes--802A, 934A, 940A, and 1366A--were common in all Iranian vvIBDVs except in one isolate. Amino acid sequences of three Iranian vvIBDVs were 100% identical and resembled vvIBDV strains from European (UK661), Asian (HK46, GZ96), and Iranian origins (IR01, SDH1). Some unique amino acid substitutions after major hydrophilic peak A in Iranian vvIBDV field isolates were observed: 231S-L, 231S-P, and 233N-K. Phylogenetic analysis showed that the Iranian vvIBDVs were closely related to European and Asian vvIBDVs. Further comprehensive investigations will provide more information on the distribution, variability, and phylogenetic relationships of different IBDVs isolated in Iran and other parts of the world.
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PMID:Molecular characterization of Iranian infectious bursal disease viruses. 1916 60

We describe the development and preliminary characterization of a recombinant canarypox virus vectored (ALVAC) vaccine for protective immunization of equids against African horse sickness virus (AHSV) infection. Horses (n=8) immunized with either of two concentrations of recombinant canarypox virus vector (ALVAC-AHSV) co-expressing synthetic genes encoding the outer capsid proteins (VP2 and VP5) of AHSV serotype 4 (AHSV-4) developed variable titres (<10-80) of virus-specific neutralizing antibodies and were completely resistant to challenge infection with a virulent strain of AHSV-4. In contrast, a horse immunized with a commercial recombinant canarypox virus vectored vaccine expressing the haemagglutinin genes of two equine influenza H3N8 viruses was seronegative to AHSV and following infection with virulent AHSV-4 developed pyrexia, thrombocytopenia and marked oedema of the supraorbital fossae typical of the "dikkop" or cardiac form of African horse sickness. AHSV was detected by virus isolation and quantitative reverse transcriptase polymerase chain reaction in the blood of the control horse from 8 days onwards after challenge infection whereas AHSV was not detected at any time in the blood of the ALVAC-AHSV vaccinated horses. The control horse seroconverted to AHSV by 2 weeks after challenge infection as determined by both virus neutralization and ELISA assays, whereas six of eight of the ALVAC-AHSV vaccinated horses did not seroconvert by either assay following challenge infection with virulent AHSV-4. These data confirm that the ALVAC-AHSV vaccine will be useful for the protective immunization of equids against African horse sickness, and avoids many of the problems inherent to live-attenuated AHSV vaccines.
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PMID:Protective immunization of horses with a recombinant canarypox virus vectored vaccine co-expressing genes encoding the outer capsid proteins of African horse sickness virus. 1949 Sep 59

A SYBR Green I based one-step real-time reverse transcriptase polymerase chain reaction was developed for the detection and differentiation of very virulent (vv) and classical strains of infectious bursal disease virus (IBDV). The assay showed high PCR efficiency >93% and high reproducibility with coefficient of variation less than 0.5%. When tested on characterized IBDV strains, the very virulent and classical-specific primers detected accurately only vvIBDV and classical IBDV strains, respectively. The diagnostic efficacy of the assay was also tested on 140 bursal samples from experimental infection and 37 bursal samples from cases suspected of IBD. The assay was able to detect IBDV from bursal samples collected at days 3 and 5 post-infection with the vvIBDV strain UPM94/273 and the classical IBDV strain D78. The assay was also able to detect bursal samples infected dually with D78 and UPM94/273. The melting temperature values of the amplification products from the classical and very virulent viral infection were statistically significant (P<0.05). The specificity of the assay for detecting IBDV from suspected cases was confirmed by sequence analysis of the VP2 gene. The assay showed high sensitivity since bursal samples which were negative for IBDV were confirmed by virus isolation and PCR amplification. Hence, the new assay offers an attractive method for rapid detection of strains of IBDV.
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PMID:Development of SYBR green I based one-step real-time RT-PCR assay for the detection and differentiation of very virulent and classical strains of infectious bursal disease virus. 1959 73

The reverse transcriptase-polymerase chain reaction followed by restriction fragment length polymorphism (RT-PCR/RFLP) technique was used to identify and characterize Pakistani field isolates of infectious bursal disease virus (IBDV). These isolates have caused heavy losses to the poultry industry (mortality up to 60%) during the period between 1999 and 2005. Ten samples (five local isolates and five commercial vaccines) were examined for IBDV. Nine samples were positive for IBDV as evidenced by the amplification of the 743-bp region of the VP2 gene by RT-PCR. The RT-PCR products were subjected to restriction enzyme digestion with BstNI, MboI, and SspI. The RFLP profiles of all samples on digestion with the MboI enzyme yielded a fragment size of 229 and 362 bp except for vaccine strain Bursine Plus, which yielded a profile of 229 and 480 bp. However, digestion with BstNI yielded two distinct RFLP patterns. The first profile was detected in field isolates ML-1/SPVC/2001 and NP2/SPVC/2002 with four fragments of 119, 154, 172, and 209 bp, resembling RFLP profiles of molecular group 4 isolates. NL-3/SPVC/2003, NK-4/SPVC/2004, and NPK-5/SPVC/2005 generated a different RFLP profile with fragments of 119, 172, and 424 bp, resembling the profiles of molecular group 6 isolates. However, all the field and vaccine strains showed the absence of SspI restriction sites in their genome. It can be concluded that the Pakistani isolates can be grouped in molecular groups 4 and 6 of IBDV.
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PMID:Molecular characterization of Pakistani field isolates of infectious bursal disease virus. 1963 Feb 41

Deformed wing virus (DWV) was first detected in the honey bee Apis mellifera by reverse transcriptase-polymerase chain reaction (RT-PCT) in the Moscow Region. Molecular phylogenetic analysis of the detected nucleotide sequence of the virus fragment VP2-VP1 of DWV demonstrated that the Russian virus sequence is united in the common cluster with all earlier revealed nucleotide sequences of DWV in the Genbank worldwide, which confirms the previous conclusions that this virus has recently distributed in the honey bee by Varroa destructor mite. It has been shown that the level of homology for all DWV nucleotide sequences is 98%, except for nucleoside sequence of 7D isolate from Turkey (96% homology), 96% homology with Kakugo virus and 84-86% homology with Varroa destructor virus 1; there is a preponderance of insignificant nucleotide substitutions, mainly transitions, which supports the evolutionary propinquity of 3 viruses.
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PMID:[RT-PCR detection of deformed wing virus in the honey bee Apis mellifera L. in the Moscow Region]. 2126 Sep 95

Bluetongue virus (BTV) and epizootic haemorrhagic disease virus (EHDV) in deer have already been isolated in Reunion Island and have caused more or less severe clinical signs in cattle (EHDV) or in sheep (BTV), as observed in 2003. In January 2009, cattle in Reunion Island showed clinical signs suggesting infection by one or the other of these arboviral diseases. A study was set up to determine the etiology of the disease. Analysis by reverse transcriptase-polymerase chain reaction (RT-PCR) performed on blood samples from 116 cattle from different districts of the island detected the presence of the EHDV genome in 106 samples and, in 5 of them, the simultaneous occurrence of BTV and EHDV. One strain of EHDV (7 isolates) and one of BTV were isolated in embryonated eggs and a BHK-21 cell culture. Group and subgroup primer-pairs were designed on the segment 2 sequences available in GenBank to identify and type the EHDV strains. Phylogenetic analysis of the genomic segment 2 (encoding the VP2 serotype-specific protein) of the isolates confirmed the serotypes of these two orbiviruses as BTV-2 and EHDV-6 and allowed them to be compared with previously isolated strains.
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PMID:Co-circulation of bluetongue and epizootic haemorrhagic disease viruses in cattle in Reunion Island. 2200 78

This study reports pediatric surveillance over 3 years for human rhinovirus (HRV) at the District Hospital of Kilifi, coastal Kenya. Nasopharyngeal samples were collected from children presenting at outpatient clinic with no signs of acute respiratory infection, or with signs of upper respiratory tract infection, and from children admitted to the hospital with lower respiratory tract infection. Samples were screened by real-time reverse transcriptase polymerase chain reaction (real-time RT-PCR) and classified further to species by nucleotide sequencing of the VP4/VP2 junction. Of 441 HRV positives by real-time RT-PCR, 332 were classified to species, with 47% (155) being HRV-A, 5% (18) HRV-B, and 48% (159) HRV-C. There was no clear seasonal pattern of occurrence for any species. The species were present in similar proportions in the inpatient and outpatient sample sets, and no significant association between species distribution and the severity of lower respiratory tract infection in the inpatients could be determined. HRV sequence analysis revealed multiple but separate clusters in circulation particularly for HRV-A and HRV-C. Most HRV-C clusters were distinct from reference sequences downloaded from GenBank. In contrast, most HRV-A and HRV-B sequences clustered with either known serotypes or strains from elsewhere within Africa and other regions of the world. This first molecular epidemiological study of HRV in the region defines species distribution in accord with reports from elsewhere in the world, shows considerable strain diversity and does not identify an association between any species and disease severity.
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PMID:Molecular epidemiology of human rhinovirus infections in Kilifi, coastal Kenya. 2243 Oct 32


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