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Development of a multiplex immunocapture PCR with colourimetric detection for viruses of banana.

A multiplex, immunocapture PCR (M-IC-PCR) was developed for the simultaneous detection of three viruses from crude sap extracts of banana and plantain (Musa spp.). A reverse transcription step was required for Banana bract mosaic virus and Cucumber mosaic virus, which have ssRNA genomes. The detection of Banana bunchy top virus (ssDNA genome) was not adversely affected by inclusion in this step. All the three viruses could be detected simultaneously from a mixed infection. Identification and detection of individual viruses was achieved through the visualisation of discretely sized PCR amplicons by gel electrophoresis. Alternatively, a colourimetric microplate detection system utilising digoxigenin-labelled virus-specific probes was used. The latter assay was up to five times more sensitive than detection by gel electrophoresis and between 25 and 625 times more sensitive than ELISA for the various viruses. Careful selection of PCR primers was necessary to ensure the detection of a wide range of virus isolates and to avoid detrimental interactions between heterologous templates and primers.

Badnavirus↗

A novel usage of random primers for multiplex RT-PCR detection of virus and viroid in aphids, leaves, and tubers.

A multiplex reverse transcription polymerase chain reaction (m-RT-PCR) was developed for the simultaneous detection of five potato viruses and a viroid. The synthesis of cDNAs used for amplification was primed by hexanucleotides (random primers, RP). An RNA extraction procedure employing DNase I, is routinely used to isolate potato viruses and viroid (Potato virus S, PVS; Potato leafroll virus, PLRV; Potato virus X, PVX; Potato virus A and Y, PVA, PVY; and Potato spindle tuber viroid, PSTVd) from infected tissues. This extraction method produced deoxy-oligonucleotides, which in turn were used to prime the reverse transcription of RNA templates of all the viruses and the viroid. A time-course study from 15 s to 30 min showed optimal oligonucleotide generation by DNase I occurred at 10 min, an incubation time already incorporated in the extraction protocol. The presence of oligonucleotides capable of priming cDNA synthesis was also demonstrated in RNA preparations from aphids, leaves, and tubers. In order to duplicate the priming of templates by oligonucleotides, commercially available hexanucleotides were used as RP. When fragments were amplified from 5'- and 3'-ends of the random primed cDNA of PVY genome, bands of similar intensity were observed. In contrast, when two fragments (short and long) from the P1 gene region of the PVA genome were amplified, the yield of the short fragment was significantly higher in intensity than that of the long fragment in random primed cDNA. Irrespective of the origin of the primers (generated during extraction vs. commercially purchased), single or multiple viruses or the viroid were detected by amplification of random primed cDNAs present individually in the reaction or in a cDNA pool consisting of five viruses and the viroid. The cDNA produced by RP or virus specific primers (SP) was used to detect PLRV and PVY from infected tubers in a duplex reverse transcription polymerase chain reaction (d-RT-PCR). The RP cDNA gave increased detection. Comparison of RP primed cDNAs from dormant or sprouted tubers and leaves showed that for some cultivars, such as 'Shepody', leaves were more reliable for PVY and PLRV detection than the tubers, in both the d- and m-RT-PCR.

Animals↗

Single-step multiplex RT-PCR for simultaneous and colourimetric detection of six RNA viruses in olive trees.

A single-step multiplex RT-PCR was developed for the simultaneous and colourimetric detection of six RNA viruses (Cucumber mosaic virus, Cherry leaf roll virus, strawberry latent ringspot virus, Arabis mosaic virus, Olive latent-1 virus and Olive latent-2 virus) which infect olive trees. Six compatible primer set for one-step RT-PCR amplification in a single closed-tube and 3' digoxigenin labelled probes were designed in optimal, specific and conserved regions. The method has been assessed with 195 Spanish field olive trees, suggesting that approximately 1.5% of the tested material was infected by Cucumber mosaic virus and 0.5% by Cherry leaf roll virus. This method saves time and reagent costs compared with monospecific RT-PCR which needs several reactions for the same number of tests. Using colourimetric detection, it is possible to analyse many samples, it increases sensitivity 10-fold, and whilst facilitating the interpretation of results, it avoids the use of gels and the toxic ethidium bromide. The method could be used routinely for sanitary and certification programmes.

Colorimetry↗

Development of a multiplex AmpliDet RNA assay for simultaneous detection and typing of potato virus Y isolates.

A multiplex AmpliDet RNA assay was developed for the specific detection of potato virus Y (PVY), and for the differentiation of the PVY(N), PVY(O/C) strains and the tuber necrotic isolates (PVY(NTN)). The assay is based on the generic amplification of a region within the coat protein coding region of all known PVY isolates by nucleic acid sequence-based amplification (NASBA) and strain-specific detection by molecular beacons. PVY(NTN)-specific diagnosis is achieved by detecting PVY(N) and PVY(O)-specific sequences flanking a recombination site that is associated with the tuber necrotic pathotype. The assay exhibited good specificity toward the various PVY strains in both single and mixed infections. The technique was validated by the use of 47 PVY isolates originating from six countries. The results of the AmpliDet RNA assay were identical or consistent with those of biological characterisation in the decisive majority of cases.

Base Sequence↗

A new approach for the simultaneous differentiation of biological and geographical strains of Potato virus Y by uniplex and multiplex RT-PCR.

Two strains of Potato virus Y (PVY), the common (PVY(O)) and the tobacco veinal necrosis (PVY(N)) have been known for decades. More recently, a tuber ringspot necrosis (PVY(NTN)), and several recombinants of PVY(O) and PVY(N) (designated here as PVY(N:O)) have been described. Further, the PVY(N) group of strains have been assigned to two geographical subgroups of European (EU) PVY(N/NTN) and the North American (NA) PVY(N/NTN). The evolution of new PVY(N) strains, has complicated the diagnosis, which requires a combination of bioassay, serological and molecular assays. To simplify the identification and differentiation of various PVY(N) strain groups, a competitive (single antisense and multiple sense primers) reverse transcription-polymerase chain reaction (RT-PCR) was used, making use of minor differences in the variable region part of the PVY genome. Specifically, primers based on small variations in nucleotide stretches of P1 gene permitted a broad range separation of PVY(O) and PVY(N) groups and the specific detection of strain subgroups. The primer pairs designed for identifying PVY(O), EU-PVY(N/NTN), NA-PVY(N) and NA-PVY(NTN) are described. Primer pairs can be used in a uniplex (single pair of primer) or multiplex (duplex, tetraplex or pentaplex) competitive RT-PCR, allowing simultaneous testing for any combination of PVY(O), EU-PVY(N/NTN), NA-PVY(N) and NA-PVY(NTN).

DNA Primers↗

Development of a multiplex real-time reverse transcriptase-polymerase chain reaction for equine infectious anemia virus (EIAV).

A single-tube reverse transcriptase-polymerase chain reaction (RT-PCR) using a fluorogenic real-time PCR detection method is described for the quantitation of equine infectious anemia virus (EIAV) RNA in the plasma of equids. To compensate for variations inherent in sample preparation a multiplex real-time RT-PCR system was developed that permitted the simultaneous calculation of the nucleic acid recovery rate along with the copy number of viral RNA molecules. Detection of EIAV RNA was linear from 10(9) to 10(1) molecules with intra- and inter-assay variability of less than 1% at 10(8), 10(6), 10(4) and 10(2) molecules.

Animals↗

Detection of rhinovirus and enterovirus in upper respiratory tract samples using a multiplex nested PCR.

Human enteroviruses and rhinoviruses are respiratory pathogens whose role in acute respiratory infection is underestimated due to the use of diagnostic procedures with poor sensitivity. To determine the prevalence of these two pathogens in the upper respiratory tract infections, a multiplex procedure was developed that both detect and differentiate rhinoviruses and enteroviruses. This sensitive procedure allowed the detection of both pathogens from archival material (nasal swabs) collected during the previous winters and differentiated rhinoviruses from enteroviruses. This procedure can be used to determine the role of these pathogens in mild or severe upper respiratory tract infections.

Animals↗

Multiplex RT-PCR detection of four aphid-borne strawberry viruses in Fragaria spp. in combination with a plant mRNA specific internal control.

The principal aphid-borne viruses infecting Strawberry (Fragaria spp.) Strawberry crinkle virus (SCV), Strawberry mild yellow edge virus (SMYEV), Strawberry mottle virus (SMoV) and Strawberry vein banding virus (SVBV) can cause serious crop losses. In this paper, a multiplex reverse transcriptase polymerase chain reaction (RT-PCR) method is described for the simultaneous detection of all four viruses in combination with a plant mRNA specific internal control which can be used as an indicator of the effectiveness of the extraction and RT-PCR. In total, 18 strawberry isolates infected naturally were analysed by this method. Every combination of RNA virus was able to be detected and a full complement of all four viruses were found together in three isolates, all taken from wild strawberry (Fragaria chiloensis (L.) Duch.) in Chile. The upper detection limit for the four viruses was at an extract dilution of 1/200. The broad applicability of the RNA specific internal control primers-which produced a PCR fragment of the expected size in 25 of 27 plant species tested-combined with improvements, made in extraction methods described provides potentially a standard method for comparable RT-PCR analyses in a wide variety of plant species.

Animals↗

High throughput screening of 16 million serologically negative blood donors for hepatitis B virus, hepatitis C virus and human immunodeficiency virus type-1 by nucleic acid amplification testing with specific and sensitive multiplex reagent in Japan.

Nationwide nucleic acid amplification testing (NAT) for hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus type 1 (HIV-1) of blood donated voluntarily after serological screening was implemented on July 1st 1999 for transfusion and plasma fractionation by the Japanese Red Cross blood transfusion services. From February 1st 2000, HBV, HCV and HIV-1 NAT screening of pools of 50 negative serologically screened donated blood was started and the results were reported within 1 day after blood donation. Systems were established for rapid shipment, electronic communication, automated specimen preparation, pooling and automated amplification and detection. At present, NAT screening is carried out within 1 day after donation. This report describes the blood screening system by NAT and the results obtained from over 16 million blood samples using simultaneous screening for HBV, HCV and HIV-1 with multiplex reagent. Between February 1, 2000 and December 31, 2002, 16012175 serologically negative units were tested by NAT. 308 units with Hepatitis B virus DNA (HBV DNA) were detected. The sensitivity of 50 pool NAT screening with input volume of 0.2 ml is significantly higher than that of highly sensitive HBsAg testing. 46 cases with HCV RNA and six cases with HIV-1 RNA were detected. These cases were not detected by HCV antibody and HIV-1 antibody screening. The false positive rate was 0.18%. The NAT system was developed from serological screening test negative non-remunerated voluntary donations. We supply blood products to medical organizations after screening by NAT for HBV, HCV and HIV-1 for transfusion and source plasma for fractionation. This is the first automated integrated system for prevention of transfusion transmitted HBV, HCV and HIV-1 infections, by NAT screening.

Antibodies, Viral↗

A simple and reliable protocol for the detection of apple stem grooving virus by RT-PCR and in a multiplex PCR assay.

Primers were identified which amplify specifically a 499 bp fragment in the coat protein coding region of apple stem grooving virus (ASGV) genome. These primers were used in various RT-polymerase chain reaction (PCR) analyses for the detection of ASGV in Chenopodium quinoa, Nicotiana occidentalis, and in species of Malus and Pyrus. Isolates of ASGV in Malus and Pyrus from locations in Canada, China, Israel, Japan, Nepal, Pakistan, South Africa, and the U.S.A. were reliably detected in leaf and bark (budwood) tissue. Storage of the tissues at -80 degrees C for more than 4 months did not affect the reliability of detection by immunocapture (IC) RT-PCR. Triton-X was not necessary for the detection of ASGV by IC/RT-PCR, and it was also possible to combine the antibody incubation and virus sap incubation into a single step without any obvious loss in sensitivity. A Tube Capture (TC) RT-PCR procedure was developed that eliminated the need for antibody binding of the virus. Phosphate buffered saline with 2% PVP was identified as the most effective sample-grinding buffer for the detection of ASGV by IC/RT-PCR and TC/RT-PCR. TC/RT-PCR facilitated the simultaneous detection (multiplex PCR) of ASGV and cherry mottle leaf virus.

Base Sequence↗

A comparison of virus isolation, indirect immunofluorescence and nested multiplex polymerase chain reaction for the diagnosis of primary and recurrent herpes simplex type 1 and type 2 infections.

134 swabs in viral transport medium were received from 126 patients with suspected clinical HSV-1 and HSV-2 infections. They were tested by (i) nested multiplex polymerase chain reaction NMPCR (strongly positive specimens had visible bands on both rounds of PCR) without prior extraction, (ii) culture in primary rhesus monkey kidney, E6-Vero, RD and HEp-2 cells and (iii) antigen detection by immunofluorescence (IF). Antigen detection employed four novel pools (A-D) of monoclonal antibodies (Mab): A was HSV-1 specific, B was HSV-2 specific while C and D were generic. In comparison to NMPCR the sensitivity and specificity of (i) culture was 59% (22/37) and 100% (134/134), (ii) IF by Pool A was 59% (16/27) and 100% (117/117), (iii) IF by Pool B was 40% (4/10) and 100% (130/130) and (iv) IF by Pools C and D were 60% (18/30) and 100% (96/96). Specimens positive by culture were more likely to be strongly positive by NMPCR (chi2 P = 0.004). Typing by each method concurred on all occasions. NMPCR was cost effective, easier to perform and was the most sensitive method for HSV detection. It should become the method of choice for HSV diagnosis.

Base Sequence↗

Measuring infectious bursal disease virus RNA in blood by multiplex real-time quantitative RT-PCR.

A quantitative reverse transcription polymerase chain reaction (RT-PCR) protocol for assessing infectious bursal disease virus (IBDV) RNA levels in blood was developed using the ABI PRISM 7700 Sequence Detection System coupled with TaqMan chemistry. To control for variations in sampling and processing between samples 28S rRNA was co-amplified in a multiplex reaction and used to quantify total RNA. Relative quantification and standardisation was achieved using a log10 dilution series of RNA extracted from IBDV stock. A linear relationship was observed between input RNA and cycle threshold values (C(T)) over 5 log10 dilutions for the IBDV-specific product and 6 log10 dilutions for the 28S rRNA-specific product. As a test of the assay it was used to determine whether differences in susceptibility to IBDV observed between inbred lines of chickens could be detected at the level of viral load in the blood. Viral RNA levels peaked 2 days post-infection when there was significantly less viral RNA in the blood of resistant line 6(1) chickens compared with the more susceptible Brown Leghorns (P = 0.01). These results demonstrate that the course of IBDV infection can be monitored by quantifying IBDV RNA extracted from blood of infected chickens using TaqMan technology.

Animals↗

Subtyping of foodborne and environmental isolates of Escherichia coli by multiplex-PCR, rep-PCR, PFGE, ribotyping and AFLP.

A total of 54 isolates were characterized by multiplex-PCR for toxin genes and genotyped using several DNA fingerprinting methods: using repetitive extragenic palindromes (REP) and Box primers (rep-PCR), amplified fragment length polymorphism (AFLP), pulsed-field gel electrophoresis (PFGE) and ribotyping. The known-pathogenic strains tested were from food and clinical samples (34 strains) and included serovars O157:H7, O111:H8, O111:H11, O91:H21 and O55:H7. Two type cultures, Escherichia coli K12 (ATCC 29425) and DUP-101 (ATCC 51739), were included as known non-pathogenic strains and an additional 17 previously unclassified isolates from animal fecal samples. Comparisons of genomic DNA fingerprint patterns using unweighted pair group method with arithmetic averages (UPGMA) cluster analysis of Jaccard similarity indices indicated that all methods tested showed a greater similarity between the E. coli O157:H7 strains than to other isolates. On the basis of these studies, we propose that AFLP, REP-PCR, Box-PCR and ribotyping techniques can all be used for discriminating O157:H7 isolates and are preferred for large-scale screening because of the speed and ease of the methods. The PFGE method is the best to discriminate between subtypes of O157:H7 associated with specific outbreak investigations; however, it is more time consuming and unnecessary if subtyping is not required. There are differences between the dendrograms generated from each method and the relationship between the other strains analyzed. However, the fingerprint profiles of the O157:H7 isolates were virtually identical using REP-PCR and Box-PCR enabling easy distinction of the group. Thus, these typing methods have the potential to aid investigators in identifying the source of an outbreak to prevent or control further spread of E. coli O157:H7.

Bacterial Toxins↗

Quantitative, multiplexed detection of bacterial pathogens: DNA and protein applications of the Luminex LabMAP system.

Escherichia coli, Salmonella, Listeria monocytogenes and Campylobacter jejuni are bacterial pathogens commonly implicated in foodborne illnesses. Generally used detection methods (i.e., culture, biochemical testing, ELISA and nucleic acid amplification) can be laborious, time-consuming and require multiple tests to detect all of the pathogens. Our objective was to develop rapid assays to simultaneously detect these four organisms through the presence of antigen or DNA using the Luminex LabMAP system. For nucleic acid detection, organism-specific capture probes corresponding to the 23S ribosomal RNA gene (rrl) were coupled covalently to LabMAP microspheres. Target molecules included synthetic complementary oligonucleotides and genomic DNA isolated from ATCC type strains or other well-characterized strains of each organism. Universal PCR primers were designed to amplify variable regions of bacterial 23S ribosomal DNA, yielding biotinylated amplicons of 86 to 109 bp in length. Varying quantities of targets were hybridized to the combined microsphere sets, labeled with streptavidin-R-phycoerythrin and analyzed on the Luminex(100) system. Results of nucleic acid detection assays, obtained in 30 to 40 min following amplification, correctly and specifically identified each bacterial species with a detection sensitivity of 10(3) to 10(5) genome copies. Capture-sandwich immunoassays were developed with organism-specific antibodies coupled to different microsphere sets. Microspheres were incubated with organism-specific standards and reactivity was assessed with biotinylated detection antibodies and streptavidin-R-phycoerythrin. In the immunoassays, microsphere-associated fluorescence was organism concentration dependent with detectable response at < or = 1000 organisms/ml and with no apparent cross-reactivity. We have demonstrated that the Luminex LabMAP system is a rapid, flexible platform capable of simultaneous, sensitive and specific detection of pathogens. The practical significance of this multiplexing approach would be to provide more timely, economical and comprehensive information than is available with conventional isolation and identification methodologies.

Antigens, Bacterial↗

Detection of pathogenic Yersinia enterocolitica in enrichment media and pork by a multiplex PCR: a study of sample preparation and PCR-inhibitory components.

A multiplex PCR assay including sample preparation was developed to detect viable pathogenic strains of Yersinia enterocolitica in PCR-inhibitory samples, such as pork and enrichment media. The method developed was used to simultaneously detect the plasmid-borne virulence gene yadA and a Yersinia-specific region of the 16S rRNA gene. According to an auto-agglutination test for virulence-plasmid-bearing strains of Y. enterocolitica, all potential pathogenic strains tested were detected by the assay. A DNA extraction procedure, an aqueous two-phase system composed of polyethylene glycol 4000 and dextran 40 and a buoyant density centrifugation method, based on Percoll, were compared with regard to their efficiency in separating Yersinia enterocolitica from PCR inhibitors originating from enrichment media and pork. Using the density gradient centrifugation method resulted in a detection level of 4.0 x 10(2) CFU Y. enterocolitica per ml enrichment media. To ensure detection of viable bacteria a short enrichment step was included in the sample preparation together with the density gradient centrifugation. When this sample treatment method was evaluated with a selective enrichment medium together with a background flora inoculated with approximately 1.0 x 10(1) CFU per ml of Y. enterocolitica and incubated at 25 degrees C, a positive PCR result was obtained after 6 to 8 h. Our results indicate that selective enrichment followed by buoyant density gradient centrifugation provides a convenient and user-friendly sample preparation method prior to PCR.

Agglutination Tests↗

Multiplex differential display identifies a novel zinc-finger protein repressed during withdrawal from cocaine.

Multiplex differential display (MDD), a modification of differential display reverse transcriptase polymerase chain reaction (DD-PCR), was used to identify cocaine-dependent regulation of previously known and unknown gene products. Direct comparison of the MDD amplification profiles of duplicate, total RNA samples from the caudate putamen (CPu) of either vehicle or cocaine treated Sprague-Dawley rats indicated that the relative induction of a 240 bp (8G247) product, likely to represent c-fos mRNA, closely paralleled changes in c-fos mRNA as measured by Northern blot analysis. MDD and Northern blot analysis also revealed substantial repression of another PCR product (8G226) at 1 h and 1 day after repeated administration of cocaine. At 2 days after cocaine exposure, the level of 8G226 had returned to control levels. The DNA sequence of 8G226 exhibited near identity with a mouse zinc-finger protein (PZf) and is thus likely to represent a transcriptional regulator. Interestingly, the repression of 8G226 immediately after cocaine treatment is in direct contrast to the cocaine-dependent increase in expression documented for NGFI-A, another zinc-finger protein which also functions as a transcriptional regulator. Detailed characterization of the prolonged reduction in the expression of 8G226 may lead to the identification of additional regulatory pathways that produce changes in cellular response after repeated cocaine exposure.

Amino Acid Sequence↗

Probing for drug-induced multiplex signal transduction pathways using high resolution two-dimensional gel electrophoresis: application to beta-adrenoceptor stimulation in the rat C6 glioma cell.

Whole-cell [(32)P]-protein phosphorylation assays and two-dimensional gel electrophoresis (2-DGE) were applied to the analysis of the beta-adrenoceptor (betaAR)-linked signal transduction pathway. Rat C6 glioma cells were stimulated with isoproterenol and the protein lysates were resolved by 2-DGE. Two dimensional [(32)P]-phosphoprotein 'maps' were generated depicting the modulation of intracellular proteins after isoproterenol stimulation versus unstimulated cells. A total of 274 distinct phosphoprotein spots were detected, of which 200 were up-regulated, 69 were down-regulated, and 5 remained unchanged. An evaluation of isoproterenol's activity across several kinase pathways was performed using a computer-generated 2-DGE template incorporating the location and identification of individual signaling phosphoprotein intermediaries. The template served as a 'reference map' for drug treatment comparisons. We observed a significant increase in the phosphorylation states of several nuclear transcription factors, notably CREB-1, ATF-1, NFkappaB/IkappaBalpha and ELK-1, but not c-Jun. A parallel series of radioimmunoprecipitation studies confirmed our 2-DGE findings. Moreover, isoproterenol increased the phosphorylation state of PKC and of several MAPK-dependent pathway kinases which correlated with a significant increase in their endogenous kinase activity. Isoproterenol's effects on PKA, PKC and ERK-dependent activities were blocked by propranolol, a betaAR antagonist. In conclusion, an acute isoproterenol stimulus induced multiplex pathway modulation via the betaAR in the C6 glioma cell indicating that signaling pathway cross-talk is an essential feature for the regulation of cellular function. Moreover, the immediate advantages of the 2-DGE analytical approach were apparent, and further development of the protein database will provide a valuable tool to screen for broad-based drug-mediated signaling activities.

Animals↗

Study of MICA alleles in 201 African Americans by multiplexed single nucleotide extension (MSNE) typing.

We have developed a method for major histocompatibility complex class I chain-related gene A (MICA) genotyping using multiplexed single nucleotide extension (MSNE) and flow cytometric analysis of an array of fluorescent microspheres. This technique employs a polymerase chain reaction-derived target DNA containing all the polymorphic sites of MICA, synthetic complementary primers, biotinylated dideoxynucleotide triphosphate, fluorescent reporter molecules (streptavidin-phycoerythrin), and thermophilic DNA polymerase. Genomic DNA was amplified by MICA locus-specific primers and the MSNE reactions were carried out in the presence of 30 MSNE primers used to assay polymorphisms in exons 2, 3, and 4 of the MICA genes. Thirty-two previously typed cell lines were used as reference material. The MICA gene frequencies among 201 African-American unrelated donors were determined. Of 51 previously known alleles, 18 were observed in African-Americans, compared to 16 that were found in North American Caucasians and 9 in South American Indians, suggesting a more diversified allelic distribution in African-Americans. MICA*00201 and MICA*00801 were the two most frequent alleles in African-Americans. We observed a high degree of linkage disequilibrium between certain alleles of MICA and of human leukocyte antigen-B in the African-American population. The methodology described here offers a powerful new approach to DNA typing of the MICA alleles.

Black or African American↗