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)

During a field study in Zimbabwe, clinical specimens were collected from 403 cattle in six herds, in which the history of foot-and-mouth disease (FMD) vaccination and infection appeared to be known with some certainty. Five herds had reported outbreaks of disease one to five months previously but clinical FMD had not been observed in the sixth herd. A trivalent vaccine (South African Territories [SAT] types 1, 2 and 3) had been used in some of the herds at various times either before and/or after the recent outbreaks of FMD. The primary aim of this study was to evaluate the performance of serological tests for the detection of SAT-type FMD virus infection, particularly elisas for antibodies to non-structural proteins (NSPs) of FMD virus and solid phase competition ELISAS (SPCEs) for serotypes SAT1 and SAT2. Secondary aims were to examine NSP seroconversion rates in cattle that had been exposed to infection and to compare virus detection rates by virus isolation and real-time reverse transcriptase-PCR (rtRT-PCR) tests on both oesophagopharyngeal fluids and nasopharyngeal brush swabbings. In addition, the hooves of sampled animals were examined for growth arrest lines as clinical evidence of FMD convalescence. Laboratory tests provided evidence of FMD virus infection in all six herds; SAT2 viruses were isolated from oesophagopharyngeal fluids collected from two herds in northern Zimbabwe, and SAT1 viruses were isolated from three herds in southern Zimbabwe. Optimised rtRT-PCR was more sensitive than virus isolation at detecting FMD virus persistence and when the results of the two methods were combined for oesophagopharyngeal fluids, between 12 and 35 per cent of the cattle sampled in the convalescent herds were deemed to be carriers. In contrast, nasopharyngeal swabs yielded only two virus-positive specimens. The overall seroprevalence in the five affected herds varied with the different NSPS from 56 per cent to 75 per cent, compared with 81 per cent and 91 per cent by homologous SPCE and virus neutralisation tests respectively. However, if serological test results were considered only for the cattle in which persistent infection with FMD virus had been demonstrated, 70 to 90 per cent scored seropositive in the different NSPs.
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PMID:Evaluation of laboratory tests for SAT serotypes of foot-and-mouth disease virus with specimens collected from convalescent cattle in Zimbabwe. 1749 71

This report describes the development of a one-step reverse transcriptase loop-mediated isothermal amplification (RT-LAMP) assay for the detection of swine vesicular disease virus (SVDV). The assay detects the virus rapidly, within 30-60 min and the result is visualised either by gel-electrophoresis or by the naked eye through the addition of SybrGreen. A collection of 28 SVDV isolates were tested positive, while heterologous viruses such as foot-and-mouth disease virus and vesicular stomatitis virus remained negative. The performance of the RT-LAMP was compared directly with real-time PCR using RNA from clinical samples including nasal swabs, serum and faeces. For nasal swabs and serum the sensitivity of the RT-LAMP was shown to be at least equivalent to real-time PCR. Interestingly, for faecal samples the RT-LAMP assay was shown to be even more sensitive than real-time PCR, possibly because it is less sensitive to inhibitory substances. This RT-LAMP assay provides a number of benefits for the diagnosis of SVD, since the assay is sensitive and rapid, and the isothermal amplification strategy used is not reliant upon expensive equipment it is particularly suited for "front line" diagnosis of SVD in modestly equipped laboratories, in field stations or in mobile diagnostic units.
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PMID:A one-step reverse transcriptase loop-mediated isothermal amplification assay for simple and rapid detection of swine vesicular disease virus. 1792 Jul 1

Large outbreaks of hand, foot, and mouth disease have been reported in the Asia Pacific region over the last few years and resulted in significant fatalities. The 2 main etiologic agents are Enterovirus 71 (EV71) and Coxsackievirus A16 (CA16). Both viruses are closely related genetically and show similar clinical symptoms. However, EV71 are associated with neurologic complications and can lead to fatalities. In this study, we developed a multiplex real-time hybridization probe reverse transcriptase polymerase chain reaction to detect and differentiate EV71 from CA16 using the LightCycler (Roche Molecular Biochemicals). Specific primers and hybridization probes were designed based on highly conserved VP1 region of EV71 or CA16. Our results showed high specificity and sensitivities in detecting EV71 or CA16 from 67 clinical specimens, and no other enterovirus serotype was detected. Rapid diagnosis to differentiate EV71 from CA16 in outbreak situations will enable pediatricians to identify and manage the patients more effectively.
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PMID:Development of multiplex real-time hybridization probe reverse transcriptase polymerase chain reaction for specific detection and differentiation of Enterovirus 71 and Coxsackievirus A16. 1839 44

A nucleic acid-based multiplexed assay was developed that combines detection of foot-and-mouth disease virus (FMDV) with rule-out assays for two other foreign animal diseases and four domestic animal diseases that cause vesicular or ulcerative lesions indistinguishable from FMDV infection in cattle, sheep and swine. The FMDV "look-alike" diagnostic assay panel contains 5 PCR and 12 reverse transcriptase PCR (RT-PCR) signatures for a total of 17 simultaneous PCR amplifications for 7 diseases plus incorporating 4 internal assay controls. It was developed and optimized to amplify both DNA and RNA viruses simultaneously in a single tube and employs Luminex liquid array technology. Assay development including selection of appropriate controls, a comparison of signature performance in single and multiplex testing against target nucleic acids, as well of limits of detection for each of the individual signatures is presented. While this assay is a prototype and by no means a comprehensive test for FMDV "look-alike" viruses, an assay of this type is envisioned to have benefit to a laboratory network in routine surveillance and possibly for post-outbreak proof of freedom from foot-and-mouth disease.
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PMID:Multiplexed molecular assay for rapid exclusion of foot-and-mouth disease. 1863 27

A case of foot-and-mouth disease (fmd) on a cattle farm in Normandy, Surrey, was confirmed on Friday August 3, 2007, the first case in the uk since 2001. The infection was detected nearby on a second farm on August 6. On September 12, fmd was confirmed on a farm approximately 20 km from Normandy in Egham, and this was followed by cases on five more farms in that area in the next three weeks. The majority of the infected farms consisted of multiple beef cattle holdings in semi-urban areas. In total, 1578 animals were culled on the infected farms, and fmd virus infection was confirmed in 278 of them by the detection of viral antigen, genome or antibodies to the virus, or by clinical signs. This paper describes the findings from animal inspections on the infected farms, including the estimated ages of the fmd lesions and the numbers of animals infected. It also summarises the test results from samples taken for investigation, including the detection of preclinically viraemic animals by using real-time reverse transcriptase-pcr.
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PMID:Clinical and laboratory investigations of the outbreaks of foot-and-mouth disease in southern England in 2007. 1867 97

The goal of this study was to identify the primary sites of replication of foot-and-mouth disease virus (FMDV) in cattle subsequent to aerogenous inoculation. A novel aerosol inoculation method was developed to simulate natural, airborne transmission and thereby allow the identification of early replication sites. Virus distribution after aerosol inoculation was compared at 24h post inoculation with simple nasal instillation. Aerosol inoculation of FMDV consistently resulted in virus detection by real-time reverse transcriptase-polymerase chain reaction and viral isolation in the soft palate, pharynx, and lungs. Viral antigen was also detected in each of these tissues by immunohistochemistry. Aerosol exposure resulted in typical clinical signs of FMD when animals were kept alive long enough to develop disease. This aerosol infection method is highly reproducible regarding inoculum dose and volume, and allowed the detailed study of early events in FMDV-infected cattle. Extensive postmortem sampling and trimodal virus detection system allows a more precise determination of FMDV localization than previously reported.
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PMID:Early events in the pathogenesis of foot-and-mouth disease in cattle after controlled aerosol exposure. 1893 Apr 17

Twenty-four specific pathogen free pigs were inoculated intradermally at the front-right heel bulb with 0.5 ml of viral suspension containing 10(6.0)tissue culture infectious dose (TCID(50)) with the porcinophillic strain (O/Taiwan/97) of foot-and-mouth disease virus (FMDV) isolated from the epizootic of FMD in Taiwan in 1997. Two pigs were euthanatized at 8 h, 1, 2, 3, 6, 8, 12, 15, 21, 26 and 63 days post-inoculation (DPI), and two pigs remained for long-term observation and terminated at 400 DPI. Typical symptoms of depression and inappetence appeared in the inoculated pigs at 1 DPI and subsided by 7 DPI. Vesicles developed in the epidermis over non-inoculated metacarpals joints at 1 DPI and vesicles in the mouth and on the snout were noticed at 2 DPI. Lesions in the feet were characterized by necrosis in the stratum spinosum, intercellular oedema, and vesicle formation accompanied by neutrophilic and mononuclear cells infiltration. Baby hamster kidney-21 cell cultures were used for virus isolation and viraemia was detected beginning at 1 DPI and persisted till 3 DPI and was no longer detectable when neutralizing antibody (NA) developed at 4 DPI. However, virus was isolated from skin samples from 1 to 12 DPI, from faeces from 2 to 8 DPI, and from 95% oesophageal-pharyngeal (OP) fluid samples at 8 HPI. Among the samples tested in this study, skin vesicles had the highest virus titre, 10(8.63) TCID(50). No virus was isolated from the skin or visceral organs obtained from post-mortem at day 15 after infection and the virus was not detectable from the OP fluid from 12 DPI till the end of this study (400 DPI). By using reverse transcriptase-polymerase chain reaction, viral RNA was detected first from the tissues at the inoculation site at 1 DPI, and still detectable at 21 DPI. Neutralizing antibody emerged at 4 DPI and the geometric mean NA titre reached to 1:861 and 1:1097 at 21 and 301 DPI respectively. The re-growth of hoof began at 21 DPI; however, minimal lesions including remnants of the old hoof were still presented at the end of this study. These results suggest that monitoring pig's hooves for residual lesions should be part of the FMD diagnosis.
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PMID:Pathology and viral distributions of the porcinophilic foot-and-mouth disease virus strain (O/Taiwan/97) in experimentally infected pigs. 1943 40

Enterovirus 71 (EV71) causes childhood hand, foot, and mouth disease and neurological complications, and no vaccines or therapeutic drugs are currently available. Formaldehyde-inactivated whole-virus vaccines derived from EV71 clinical isolates and a mouse-adapted virus (MAV) were tested in a mouse model of EV71 encephalomyelitis. After only two immunizations, given to mice at 1 and 7 days of age, the MAV vaccine protected mice at 14 days of age from disease. Tissues from immunized mice were negative for virus by viral culture, reverse transcriptase PCR, immunohistochemistry analysis, and in situ hybridization. Cross-neutralizing EV71 antibodies to strains with genotypes B3, B4, and C1 to C5 generated in immunized adult mice were able to passively protect 14-day-old mice from disease.
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PMID:Formaldehyde-inactivated whole-virus vaccine protects a murine model of enterovirus 71 encephalomyelitis against disease. 1986 78

The ability of foot-and-mouth disease (FMD) vaccine to protect sheep and goats from a homologous direct in-contact challenge and the effect on virus excretion from the nasal secretions and oropharynx was examined. An experimental oil adjuvant O(1) Manisa FMD vaccine protected sheep and goats from clinical disease from 7 days post vaccination following 24 hours of direct in-contact exposure to four infected donor sheep or goats. Goats required lower antibody titres for protection when compared with sheep. Protection from clinical disease did not prevent localized viral replication in goats and at least two goats had viral RNA detected on day 28 post challenge. Quantitative reverse transcriptase polymerase chain reaction showed that the level of virus replication shortly after direct in-contact challenge in oropharynx and nasal secretions of vaccinated animals was reduced by 100 and 1000 times respectively when compared with unvaccinated controls. The findings also show that after direct in-contact challenge, use of FMD vaccine will prevent or reduce local virus replication, thereby significantly reduce the amount of virus released into the environment in the all-important early post-exposure period. There is low risk of vaccinated animals transmitting disease as live virus could not be readily isolated.
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PMID:Protection against direct in-contact challenge following foot-and-mouth disease vaccination in sheep and goats: the effect on virus excretion and carrier status. 2035 90

The objective of this study was to investigate the inactivation and degradation of foot-and-mouth disease (FMD) virus during composting of infected pig carcasses as measured by virus isolation in tissue culture and by real-time reverse transcriptase polymerase chain reaction (RRT-PCR). Three FMD-infected pig carcasses were composted in a mixture of chicken manure and wood shavings in a biocontainment level 3 facility. Compost temperatures had reached 50 degrees C and 70 degrees C by days 10 and 19, respectively. Under these conditions, FMD virus was inactivated in specimens in compost by day 10 and the viral RNA was degraded in skin and internal organ tissues by day 21. In comparison, at ambient temperatures close to 20 degrees C, FMD virus survived to day 10 in the skin tissue specimen from the pig that had the highest initial level of viral RNA in its tissues and the viral RNA persisted to day 21. Similarly, beta-actin mRNA, tested as a PCR control, persisted to day 21 in specimens held at ambient temperatures, but it was degraded in the remnants of tissues recovered from compost on day 21. Results from this study provide evidence that composting could be used for safe disposal of pig carcasses infected with FMD virus.
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PMID:Degradation of foot-and-mouth disease virus during composting of infected pig carcasses. 2035 57


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