scholarly journals Real-Time Polymerase Chain Reaction for One-Hour On-Site Diagnosis of Pierce's Disease of Grape in Early Season Asymptomatic Vines

2002 ◽  
Vol 92 (7) ◽  
pp. 721-728 ◽  
Author(s):  
N. W. Schaad ◽  
D. Opgenorth ◽  
P. Gaush
Keyword(s):  
Polymerase Chain Reaction ◽  
Real Time ◽  
Real Time Pcr ◽  
Xylella Fastidiosa ◽  
Molecular Techniques ◽  
Plant Diseases ◽  
Pierce's Disease ◽  
Chain Reaction ◽  
Pierce’S Disease ◽  
Polymerase Chain

Molecular-based techniques, such as polymerase chain reaction (PCR), can reduce the time needed for diagnosis of plant diseases when compared with classical isolation and pathogenicity tests. However, molecular techniques still require 2 to 3 days to complete. To the best of our knowledge, we describe for the first time a real-time PCR technique using a portable Smart Cycler for one-hour on-site diagnosis of an asymptomatic plant disease. Pierce's disease (PD) of grape, caused by the fastidious bacterium Xylella fastidiosa, causes serious losses in grapes in California and the southeastern United States. The disease has been difficult to diagnose because typical leaf scorching symptoms do not appear until late (June and after) in the season and the organism is very difficult to isolate early in the season. Sap and samples of macerated chips of secondary xylem from trunks of vines were used in a direct real-time PCR without extraction of DNA. Using two different sets of primers and probe, we diagnosed PD in 7 of 27 vines (26%) from four of six vineyards sampled 10 to 12 days after bud break in Kern, Tulare, and Napa counties of California. The diagnosis was confirmed by isolation of Xylella fastidiosa from two of the original PCR positive samples and later from symptomatic leaf petioles of four out of four vines from one vineyard that were originally PCR positive.

scholarly journals DETEKSI CLOSTRIDIUM DIFFICILE TOKSIGENIK MENGGUNAKAN UJI CEPAT TOKSIN DAN REAL TIME POLYMERASE CHAIN REACTION (Toxigenic Clostridium Difficile Detection Using Toxin Rapid Test and Real Time Polymerase Chain Reaction)

2018 ◽  
Vol 22 (1) ◽  
pp. 22
Author(s):  
Ika Yasma Yanti ◽  
Dalima Ari Wahono Astrawinata
Keyword(s):  
Polymerase Chain Reaction ◽  
Clostridium Difficile ◽  
Antibiotic Therapy ◽  
Real Time ◽  
Real Time Pcr ◽  
Rapid Test ◽  
Chain Reaction ◽  
Chi Square ◽  
Polymerase Chain ◽  
Clostridium Difficile Associated Diarrhea

Toxigenic Clostridium difficile infection, causing a Pseudo Membrane Colitis (PMC) and Clostridium Difficile Associated Diarrhea(CDAD) has increased sharply. The largest risk factor is the use of antibiotics. The purpose of this study was to know how to determinethe prevalence and characteristics of subjects with Toxigenic Clostridium difficile and to assess the ability of the toxin rapid test comparedto real-time PCR. Ninety adult subjects with antibiotic therapy more than two (2) weeks were enrolled in this study. The results of toxinrapid test and real-time PCR were presented in a 2x2 table, statistical test used was Chi square. The prevalence of Toxigenic Clostridiumdifficile based on the toxin rapid test and by real-time PCR was 27.3% and 37.5%, respectively. There were significant differences betweenstool consistency and number of antibiotics used with the detection of Toxigenic Clostridium difficile. There was a relationship betweenthe duration of antibiotic therapy with the detection of Toxigenic Clostridium difficile using real-time PCR (p=0.010, RR=2.116). Thesensitivity, specificity, PPV, NPV, PLR and NLR rapid test against real-time PCR were 69.7%; 98.2%; 95.8%; 84.4%; 39.2 and 0.31,respectively. This study concluded that the prevalence of Clostridium difficile in RSCM was higher compared to that in Malaysia, Thailandand India; the subjects with antibiotic therapy for more than four (4) weeks had a double risk to have Toxigenic Clostridium difficilethan subjects with antibiotic therapy for less than that time (4 weeks). Thus, in this study, toxin rapid test could be used as a tool todetect Toxigenic Clostridium difficile.

Quantitative Real-Time Polymerase Chain Reaction Detection of BK Virus Using Labeled Primers

2010 ◽  
Vol 134 (3) ◽  
pp. 444-448 ◽  
Author(s):  
Zhengming Gu ◽  
Jianmin Pan ◽  
Matthew J. Bankowski ◽  
Randall T. Hayden
Keyword(s):  
Polymerase Chain Reaction ◽  
Real Time ◽  
Real Time Pcr ◽  
Quantitative Polymerase Chain Reaction ◽  
Bk Virus ◽  
Clinical Samples ◽  
Quantitative Detection ◽  
Chain Reaction ◽  
Pcr Method ◽  
Polymerase Chain

Abstract Context.—BK virus infections among immunocompromised patients are associated with disease of the kidney or urinary bladder. High viral loads, determined by quantitative polymerase chain reaction (PCR), have been correlated with clinical disease. Objective.—To develop and evaluate a novel method for real-time PCR detection and quantification of BK virus using labeled primers. Design.—Patient specimens (n = 54) included 17 plasma, 12 whole blood, and 25 urine samples. DNA was extracted using the MagNA Pure LC Total Nucleic Acid Isolation Kit (Roche Applied Science, Indianapolis, Indiana); sample eluate was PCR-amplified using the labeled primer PCR method. Results were compared with those of a user-developed quantitative real-time PCR method (fluorescence resonance energy transfer probe hybridization). Results.—Labeled primer PCR detected less than 10 copies per reaction and showed quantitative linearity from 101 to 107 copies per reaction. Analytical specificity of labeled primer PCR was 100%. With clinical samples, labeled primer PCR demonstrated a trend toward improved sensitivity compared with the reference method. Quantitative assay comparison showed an R2 value of 0.96 between the 2 assays. Conclusions.—Real-time PCR using labeled primers is highly sensitive and specific for the quantitative detection of BK virus from a variety of clinical specimens. These data demonstrate the applicability of labeled primer PCR for quantitative viral detection and offer a simplified method that removes the need for separate oligonucleotide probes.

scholarly journals Sensitive SYBR Green—Real Time PCR for the Detection and Quantitation of Avian Rotavirus A

2018 ◽  
Vol 6 (1) ◽  
pp. 2 ◽  
Author(s):  
David De la Torre ◽  
Claudete Astolfi-Ferreira ◽  
Ruy Chacon ◽  
Antonio Piantino Ferreira
Keyword(s):  
Polymerase Chain Reaction ◽  
Real Time ◽  
Sybr Green ◽  
Molecular Techniques ◽  
Economic Losses ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Rotavirus A ◽  
Avian Nephritis Virus ◽  
Polymerase Chain

Avian rotavirus A (ARtV-A) is a virus that affects young birds, causing acute diarrhea and economic losses in the poultry industry worldwide. The techniques used for the diagnosis of ARtV-A include electron microscopy, isolation in cell culture, and serology, as well as molecular techniques, such as the reverse transcription-polymerase chain reaction (RT-PCR). The objective of this work was to standardize a real-time RT-polymerase chain reaction (RT-qPCR) using SYBR Green chemistry for the rapid detection and quantification of ARtV-A from bird tissues and materials fixed on FTA cards on the basis of the nucleotide sequence of segment 6 (S6), which codes for the structural VP6 protein of ARtV-A. The results show the efficient amplification of the proposed target, with a limit of detection (LoD) of one copy gene (CG) per microliter of cDNA and a limit of quantification (LoQ) of 10 CGs per microliter. The efficiency of the primers was determined to be 95.66% using a standard curve, with an R2 value of 0.999 and a slope of −3.43. The specificity was determined using samples coinfected with ARtV-A, the chicken parvovirus, the chicken astrovirus, and the avian nephritis virus as positive controls and commercially available vaccines of the infectious bronchitis virus, infectious bursa disease virus, avian reovirus and healthy organs as negative controls. This technique, which lacks nonspecific PCR products and dimers, demonstrated greater sensitivity and specificity than conventional RT-PCR, and it reduced the analysis time by more than 50%.

scholarly journals In Planta Distribution of ‘Candidatus Liberibacter asiaticus’ as Revealed by Polymerase Chain Reaction (PCR) and Real-Time PCR

2008 ◽  
Vol 98 (5) ◽  
pp. 592-599 ◽  
Author(s):  
Satyanarayana Tatineni ◽  
Uma Shankar Sagaram ◽  
Siddarame Gowda ◽  
Cecile J. Robertson ◽  
William O. Dawson ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Real Time ◽  
Real Time Pcr ◽  
Citrus Tree ◽  
Candidatus Liberibacter Asiaticus ◽  
In Planta ◽  
Chain Reaction ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus ◽  
Polymerase Chain

Huanglongbing (HLB) is one of the most devastating diseases of citrus worldwide, and is caused by a phloem-limited fastidious prokaryotic α-proteobacterium that is yet to be cultured. In this study, a combination of traditional polymerase chain reaction (PCR) and real-time PCR targeting the putative DNA polymerase and 16S rDNA sequence of ‘Candidatus Liberibacter asiaticus,’ respectively, were used to examine the distribution and movement of the HLB pathogen in the infected citrus tree. We found that ‘Ca. Liberibacter asiaticus’ was distributed in bark tissue, leaf midrib, roots, and different floral and fruit parts, but not in endosperm and embryo, of infected citrus trees. Quantification analysis of the HLB bacterium indicated that it was distributed unevenly in planta and ranged from 14 to 137,031 cells/μg of total DNA in different tissues. A relatively high concentration of ‘Ca. Liberibacter asiaticus’ was observed in fruit peduncles. Our data from greenhouse-infected plants also indicated that ‘Ca. Liberibacter asiaticus’ was transmitted systemically from infection site to different parts of the plant. Understanding the distribution and movement of the HLB bacterium inside an individual citrus tree is critical for discerning its virulence mechanism and to develop management strategies for HLB.

Real-Time Polymerase Chain Reaction Detection of Asymptomatic Clostridium difficile Colonization and Rising C. difficile–Associated Disease Rates

2014 ◽  
Vol 35 (6) ◽  
pp. 667-673 ◽  
Author(s):  
Hoonmo L. Koo ◽  
John N. Van ◽  
Meina Zhao ◽  
Xunyan Ye ◽  
Paula A. Revell ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Clostridium Difficile ◽  
Real Time ◽  
Real Time Pcr ◽  
Pcr Detection ◽  
Adult Patients ◽  
Incidence Density ◽  
Enzyme Linked Immunosorbent Assay ◽  
Chain Reaction ◽  
Polymerase Chain

Objective.To evaluate the accuracy of real-time polymerase chain reaction (PCR) for Clostridium difficile–associated disease (CDAD) detection, after hospital CDAD rates significantly increased following real-time PCR initiation for CDAD diagnosis.Design.Hospital-wide surveillance study following examination of CDAD incidence density rates by interrupted time series design.Setting.Large university-based hospital.Participants.Hospitalized adult patients.Methods.CDAD rates were compared before and after real-time PCR implementation in a university hospital and in the absence of physician and infection control practice changes. After real-time PCR introduction, all hospitalized adult patients were screened for C. difficile by testing a fecal specimen by real-time PCR, toxin enzyme-linked immunosorbent assay, and toxigenic culture.Results.CDAD hospital rates significantly increased after changing from cell culture cytotoxicity assay to a real-time PCR assay. One hundred ninety-nine hospitalized subjects were enrolled, and 101 fecal specimens were collected. C. difficile was detected in 18 subjects (18%), including 5 subjects (28%) with either definite or probable CDAD and 13 patients (72%) with asymptomatic C. difficile colonization.Conclusions.The majority of healthcare-associated diarrhea is not attributable to CDAD, and the prevalence of asymptomatic C. difficile colonization exceeds CDAD rates in healthcare facilities. PCR detection of asymptomatic C. difficile colonization among patients with non-CDAD diarrhea may be contributing to rising CDAD rates and a significant number of CDAD false positives. PCR may be useful for CDAD screening, but further study is needed to guide interpretation of PCR detection of C. difficile and the value of confirmatory tests. A gold standard CDAD diagnostic assay is needed.Infect Control Hosp Epidemiol 2014;35(6):667–673

Quantitative assessment of hematopoietic chimerism after bone marrow transplantation by real-time quantitative polymerase chain reaction

Blood ◽  
2002 ◽  
Vol 99 (12) ◽  
pp. 4618-4625 ◽  
Author(s):  
Mehdi Alizadeh ◽  
Marc Bernard ◽  
Bruno Danic ◽  
Charly Dauriac ◽  
Brigitte Birebent ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Stem Cell ◽  
Real Time ◽  
Real Time Pcr ◽  
Quantitative Assessment ◽  
Quantitative Polymerase Chain Reaction ◽  
Chain Reaction ◽  
Hematopoietic Stem ◽  
Pcr Method ◽  
Polymerase Chain

We have developed a real-time quantitative polymerase chain reaction (PCR) assay using TaqMan technology (Applied Biosystems, Foster City, CA) for monitoring donor cell engraftment in allogenic hematopoietic stem cell transplant recipients. For this purpose, we selected 19 specific sequence polymorphisms belonging to 11 human biallelic loci located on 9 different chromosomes. Using a set of specially designed primers and fluorogenic probes, we evaluated the 19 markers' informativity on a panel of 126 DNA samples from 63 recipient/donor pairs. In more than 90% of these pairs, discrimination between recipient and donor genetic profile was possible. By using serial dilutions of mixed DNAs, we evaluated the linearity and sensitivity of the method. A linear correlation with rhigher than 0.98 and a sensitivity of 0.1% proved reproducible. Fluorescent-based PCR of short tandem repeats (STR-PCR) and real-time PCR chimerism assay were compared with a panel of artificial cell mixtures. The main advantage of the real-time PCR method over STR-PCR chimerism assays is the absence of PCR competition and plateau biases, and results evidenced greater sensitivity and linearity with the real-time PCR method. Furthermore, different samples can be tested in the same PCR run with a final result in fewer than 48 hours. Finally, we prospectively analyzed patients who received allografts and present 4 different clinical situations that illustrate the informativity level of our method. In conclusion, this new assay provides an accurate quantitative assessment of mixed chimerism that can be useful in guiding early implementation of additional treatments in hematopoietic stem cell transplantation.

Quantitative detection of human enteric adenoviruses in river water by microfluidic digital polymerase chain reaction

2014 ◽  
Vol 70 (3) ◽  
pp. 555-560 ◽  
Author(s):  
Naohiro Kishida ◽  
Naohiro Noda ◽  
Eiji Haramoto ◽  
Mamoru Kawaharasaki ◽  
Michihiro Akiba ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Real Time ◽  
River Water ◽  
Water Samples ◽  
Real Time Pcr ◽  
Quantitative Detection ◽  
Chain Reaction ◽  
Polymerase Chain ◽  
Digital Polymerase Chain Reaction ◽  
Enteric Adenoviruses

We describe an assay for simple and accurate quantification of human enteric adenoviruses (EAdVs) in water samples using a recently developed quantification method named microfluidic digital polymerase chain reaction (dPCR). The assay is based on automatic distribution of reaction mixture into a large number of nanolitre-volume reaction chambers and absolute copy number quantification from the number of chambers containing amplification products on the basis of Poisson statistics. This assay allows absolute quantification of target genes without the use of standard DNA. Concentrations of EAdVs in Japanese river water samples were successfully quantified by the developed dPCR assay. The EAdVs were detected in seven of the 10 samples (1 L each), and the concentration ranged from 420 to 2,700 copies/L. The quantified values closely resemble those by most probable number (MPN)-PCR and real-time PCR when standard DNA was validated by dPCR whereas they varied substantially when the standard was not validated. Accuracy and sensitivity of the dPCR was higher than those of real-time PCR and MPN-PCR. To our knowledge, this is the first study that has successfully quantified enteric viruses in river water using dPCR. This method will contribute to better understanding of existence of viruses in water.

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