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

---

Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Experiments were performed in chickens to ascertain whether application of infectious bronchitis (IB) H120 vaccine had an effect on the replication of an attenuated avian pneumovirus (APV) strain, using as indicators virus detection, humoral antibody responses and clinical protection against in vivo APV challenge. A preliminary experiment demonstrated that pharyngeal swabs were as efficient for recovery of APV as were buccal cavity swabs, and that either site was superior to swabbing the nasal cavity. APV was detected to a similar extent by both a reverse transcriptase-polymerase chain reaction (RT-PCR) and virus isolation; therefore, RT-PCR was used in subsequent experiments. In chickens vaccinated with APV alone, APV was detected by RT-PCR in most birds for 1 week after vaccination. When IB vaccine had been applied 1 week earlier, APV detection was delayed and much reduced. This interference by IBV resulted in a lower APV antibody response to vaccination. Following challenge with virulent APV, birds that had been vaccinated with APV alone were fully protected both clinically and virologically. Chickens that had received both vaccines were still protected clinically, but challenge virus could be detected in some pharyngeal swabs 4 days after challenge. In contrast, the APV vaccine had no effect on either the antibody response to the IB vaccine or the level of protection against IB challenge. It is concluded that IB vaccination interferes with the replication of APV, resulting in a reduction in the antibody response but with no adverse effect on the induction of protective immunity.
...
PMID:Infectious bronchitis virus vaccine interferes with the replication of avian pneumovirus vaccine in domestic fowl. 1918 5

Infectious bronchitis virus (IBV) was isolated from each of 236 broiler flocks that had respiratory infection (86%), impaired growth, enteritis and/or nephritis (14%), over a 10-year period from 1986 to 1995 in Belgium. Among them, 65% of the investigated flocks had not been vaccinated against infectious bronchitis. Type-specific reverse transcriptase polymerase chain reactions (RT-PCRs) were used after propagation of the isolates in embryonated eggs in order to detect and differentiate Massachusetts, D274, B1648 and 793/B types. The incidence of these types was approximately 50, 38, 11 and 1%, respectively. In 16% of cases, two or three types of IBV were detected, representing mostly combinations of Massachusetts and D274. The majority of the Massachusetts and D274 isolates (68 and 69%, respectively) were recovered from non-vaccinated flocks, confirming that such flocks are at greatest risk of infection by these types of IBV. Interestingly, the B1648 type was isolated from more vaccinated flocks (14%) than non-vaccinated flocks (7.6%). Most surprising was the very low incidence (1%) of the 793/B type, which was the dominant type in some neighbouring countries, during the period of investigation. The DNA derived by RT-PCR from 24 of the Massachusetts-type isolates from 12 vaccinated and 12 non-vaccinated flocks was sequenced and compared with the sequence of Massachusetts vaccines used in Belgium. This revealed that the sequence of four of the isolates (two from vaccinated and two from non-vaccinated flocks) was identical to that of a Massachusetts vaccine strain. Similar results were obtained for D274 isolates when compared with the sequence of D274 vaccines. These sequencing results demonstrate a co-circulation of vaccine and wild-type infectious bronchitis viruses in broilers, and are further justification for permanent monitoring of circulating strains in order to rationally modify vaccination strategies to make them appropriate to the field situation.
...
PMID:Epidemiology of infectious bronchitis virus in Belgian broilers: a retrospective study, 1986 to 1995. 1918 26

Polymerase chain reaction (PCR)-based approaches to the detection, differentiation and characterization of avian pathogens continue to be developed and refined. The PCRs, or reverse transcriptase-PCRs, may be general, designed to detect all or most variants of a pathogen, or to be serotype, genotype or pathotype specific. Progress is being made with respect to making nucleic acid approaches more suitable for use in diagnostic laboratories. Robotic workstations are now available for extraction of nucleic acid from many samples in a short time, for routine diagnosis. Following general PCR, the DNA products are commonly analyzed by restriction endonuclease mapping (restriction fragment length polymorphism), using a small number of restriction endonucleases, based on a large body of sequence data. Increasingly, however, nucleotide sequencing is being used to analyze the DNA product, in part due to the expanding use of non-radioactive sequencing methods that are safe and enable high throughout. In this review, I highlight some recent developments with many avian viruses: Newcastle disease virus; circoviruses in canary and pigeon; infectious bursal disease virus (Gumboro disease virus); avian adenoviruses, including Angara disease/infectious hydropericardium virus, haemorrhagic enteritis virus of turkeys, and egg drop syndrome virus; avian herpesviruses, including infectious laryngotracheitis virus, duck plague virus, psittacine herpesvirus (Pacheco's parrot disease virus), Marek's disease virus and herpesvirus of turkeys; avian leukosis virus (associated with lymphoid leukosis or myeloid leukosis, and egg transmission); avian pneumoviruses (turkey rhinotracheitis virus); avian coronaviruses, including infectious bronchitis virus, turkey coronavirus and pheasant coronavirus; astrovirus, in the context of poult enteritis and mortality syndrome, and avian nephritis virus; and avian encephalomyelitis virus, a picornavirus related to hepatitis A virus.
...
PMID:Innovation and discovery: the application of nucleic acid-based technology to avian virus detection and characterization. 1918 52

To understand the genetic diversity of the S2 gene of infectious bronchitis viruses (IBV) isolated in Japan, we determined the nucleotide sequences of these IBVs using the reverse transcriptase polymerase chain reaction method coupled with direct sequencing. IBV isolated in Japan were classified into six different groups by phylogenetic analysis based on the S2 gene. However, the classification based on the S2 gene of IBV isolated in Japan was different for some of the strains from those obtained with our previous analysis of the S1 gene. This suggested that genetic recombination between the virus strains classified into different genetic groups had occurred in poultry, and that recombinant viruses might be epidemic in Japan.
...
PMID:Genetic diversity of avian infectious bronchitis viruses in Japan based on analysis of s2 glycoprotein gene. 1934 95

The effects of glycyrrhizin diammonium (GD) and lithium chloride (LiCl) on cell infection by avian infectious bronchitis virus (IBV) were investigated using cytopathic effect observation, plaque-reduction assay and reverse transcriptase-polymerase chain reaction. The anti-viral effect of GD and LiCl on virus, on virus-infected cells or on cells pre-treated by both drugs was analysed, respectively. Our results showed that GD had a direct antiviral activity, leading to complete inhibition of cell infection. The cell infection was not alleviated by either pre-treatment of cells with GD or addition of the drug post infection, confirming that the inhibitory effect of GD, unlike LiCl, on IBV is a viral factor, rather than a cellular factor. The inhibitory effect of both drugs was confirmed by infecting primary chicken embryo kidney cells. In addition, apoptosis of infected cells was positively related with cytopathic effect and could be inhibited by effective drug treatment. Our data indicate that GD and LiCl have potential to prevent IBV infection in vitro through different antiviral mechanisms. The data are helpful for using antivirals efficiently.
...
PMID:Comparative analysis of the effect of glycyrrhizin diammonium and lithium chloride on infectious bronchitis virus infection in vitro. 1946 38

To determine the coverage of infectious bronchitis virus (IBV) vaccine field boost in commercial broilers, estimate the relative amount of vaccine virus in the trachea, and follow the clearance of the vaccine, we collected approximately 100 tracheal swabs at various times postvaccination from 10 different flocks and used real-time reverse transcriptase-PCR (RT-PCR) to detect the virus. This allowed us to detect vaccine virus in as few as 3% of the birds in a flock of 20,000 birds with a 95% confidence level. We found that the number of birds positive for IBV vaccine following vaccination in the field resembled a parabolic-shaped curve that peaked around 14 days postvaccination, or it resembled a sinusoidal-type wave with a frequency of about 2 wk. The patterns did not appear to correlate with water or spray vaccination methods, nor did they correlate with the type of backpack sprayer used. The highest number of positive birds in a flock ranged from 66% to 100%. The viral genome copies in the tracheal swabs, as determined by real-time RT-PCR, ranged from 1 x 10(2.6)/ml to 1 x 10(5.2)/ml and, in most studies, had a positive correlation with the number of birds positive for vaccine virus in the flock. On the last sample day of each study, 21, 28, or 35 days postvaccination, from 12% to 66% of the birds were still positive for vaccine virus, and although different IBV vaccine types were used in each study, only Arkansas vaccine virus was identified in selected samples on those days. Arkansas vaccine virus was also the only virus identified in selected samples at 1, 3, and 5 days postvaccination, clearly indicating that Arkansas vaccine virus is persisting in the birds. Protection studies conducted on birds vaccinated with Arkansas- and Delaware-type vaccines and removed from the field at 21 days postvaccination showed complete protection against challenge with Delaware (except for one bird), whereas protection against Arkansas challenge was between 37.5% and 62.5%. Our findings show that introduction of IBV vaccines into a commercial broiler flock do not necessarily follow a seemingly logical pattern of a high number of birds infected followed by clearance from the trachea, but resembled either a parabolic curve or a sinusoidal-type wave. In addition, Arkansas vaccine viruses are clearly persisting in commercial broilers, which may be because of incomplete protection observed for that IBV type.
...
PMID:Infectious bronchitis virus field vaccination coverage and persistence of Arkansas-type viruses in commercial broilers. 1963 Feb 21

Turkey coronavirus (TCoV) is a causative agent associated with poult enteritis and mortality syndrome (PEMS) in turkeys worldwide. The disease is an acute, highly contagious enteric disease that is characterized by depression, anorexia, diarrhea, and high mortality in commercial turkey flocks. The presence of TCoV in 12 intestinal-content samples, from turkey flocks aged between 10 and 104 days and exhibiting severe enteritis, was monitored during the period of 2004 to 2006. TCoV detection was accomplished by a reverse transcriptase-polymerase chain reaction (RT-PCR) through amplification of the 3' UTR region, followed by amplification of genes 3 and 5. Molecular characterization of the viruses was done through amplification of genes 3 and 5 and showed evidence of genetic similarity between them, although they differed from sequences of other TCoVs described in the literature. In relation to gene 3, samples showed a greater relationship with chicken infectious bronchitis virus (IBV), while gene 5 showed greater identity with pheasant coronavirus (PhCoV). Our results suggest that the strategy of amplification of the 3' UTR region, followed by sequencing of genes 3 and 5, has proven to be an effective means of detecting TCoV in intestinal contents.
...
PMID:Detection and molecular characterization of gene 3 and 5 of turkey coronavirus from turkeys with severe enteritis in Brazil. 1984 72

Infectious bronchitis viruses (IBVs) in Taiwan have been divided into two genogroups, Taiwan group I (TW-I) and Taiwan group II (TW-II). Heterologous Mass-type strains are widely used as vaccines in the field. This work reports on a rapid and reliable multiplex reverse transcriptase-polymerase chain reaction (mRT-PCR) assay for the genotyping of IBVs. Multiplex primer sets were designed to amplify the region covering hypervariable regions 1 and 2 of the S1 glycoprotein gene. Several local strains and commercially available vaccines were used for evaluating the viral genotyping assay, and a number of field isolates were examined for clinical application. The results showed that all of the examined IBVs were accurately genotyped by identifying the corresponding bands on agarose gels (TW-I: 322 bp, TW-II: 161 bp, Mass type: 256 bp) after the mRT-PCR, in agreement with the viral genome sequence data. The mRT-PCR assay was able to detect viral RNA copies as low as 10(3), 10(50, and 10(3) for the TW-I, TW-II, and Mass-type strains, respectively. The mRT-PCR assay accurately detected and discriminated vaccine viruses from wildtype strains in the field. This assay may be beneficial for virus identification and differentiation in routine disease surveillance.
...
PMID:A multiplex reverse transcriptase-PCR assay for the genotyping of avian infectious bronchitis viruses. 2040 7

In the present study we describe the rapid development of an attenuated live vaccine for GA08, a new serotype of infectious bronchitis virus, using a heat-treatment method. Incubation of the GA08 strain of IBV at 56 degrees C and passage in embryonated eggs was used as a method to fast track the attenuation process. The virus was incubated in a 56 degrees C water bath and aliquots were removed every 5 min for up to 1 h, and then each aliquot was inoculated into 10-day-old embryonated eggs. Virus with the longest incubation time that produced lesions in the embryos was harvested, again incubated at 56 degrees C as described and passaged in embryonated eggs. Attenuation of the virus, designated GA08/GA08HSp16/08, was verified in 1-day-old specific pathogen free chicks. A 10x dose of the vaccine was found to be safe for 2-week-old broiler chicks of commercial origin. The efficacy of the heat-treated attenuated virus was determined by vaccinating broiler chicks of commercial origin at 1 and 14 days of age intraocularly/intranasally. Vaccinated birds that were challenged with 10(4.5) median embryo infectious doses of pathogenic GA08 virus/bird at 28 days of age were protected from the disease, and challenge virus was only detected in the trachea of one of 21 birds by real-time reverse transcriptase-polymerase chain reaction at 5 days post challenge. The attenuation process took 10 weeks to complete, which is a substantially shorter time than required to attenuate infectious bronchitis virus by serial passage in embryonated eggs without heat treatment (38 weeks or more).
...
PMID:Rapid heat-treatment attenuation of infectious bronchitis virus. 2054 30

We analyzed the clinical features of inpatients at a Japanese pediatric department who were infected with pandemic (H1N1) 2009 virus. Study participants included 46 children hospitalized from July 2009 to January 2010. Infection with the virus was confirmed using real-time reverse transcriptase polymerase chain reaction (RT-PCR). The epidemic month was October 2009; 34 patients were boys, and median age was 7 years. Pandemic influenza-associated respiratory diseases included pneumonia (n = 42), bronchitis (n = 3), and pharyngitis (n = 1). The median time from onset to admission was 3 days. Children were divided into those with severe (n = 32) versus nonsevere illnesses (n = 14) according to Japanese guidelines. Significant features in the severe group were younger age, previous asthmatic attack, exacerbation of asthma, decreased oxygen saturation, elevated white blood cell/neutrophil counts and serum lactate dehydrogenase, and longer times from admission to being afebrile and discharged. Both groups showed lymphopenia at admission. Additional infection with Streptococcus pneumoniae was frequent in the severe group. Whereas 44 patients received antiviral therapy (median times from onset to initiation 2 days), 32 received antibiotics (median duration 7 days). All children recovered, with a median hospital stay of 8 days. Our observations suggest that history of asthma and preschool age might be risk factors for severe illness. Prompt initiation of antiviral and antibiotic treatments should be considered to prevent development of severe illness.
...
PMID:Characteristic findings of pediatric inpatients with pandemic (H1N1) 2009 virus infection among severe and nonsevere illnesses. 2082 63


<< Previous 1 2 3 4 5 6 7 Next >>

---