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At least 163 records · Page 9Linked to original sources

PubMed2003

A novel multiplex quantitative DNA array based PCR (MQDA-PCR) for quantification of transgenic maize in food and feed.

We have developed a novel multiplex quantitative DNA array based PCR method (MQDA-PCR). The MQDA-PCR is general and may be used in all areas of biological science where simultaneous quantification of multiple gene targets is desired. We used quantification of transgenic maize in food and feed as a model system to show the applicability of the method. The method is based on a two-step PCR. In the first few cycles bipartite primers containing a universal 5' 'HEAD' region and a 3' region specific to each genetically modified (GM) construct are employed. The unused primers are then degraded with a single-strand DNA-specific exonuclease. The second step of the PCR is run containing only primers consisting of the universal HEAD region. The removal of the primers is essential to create a competitive, and thus quantitative PCR. Oligo nucleotides hybridising to internal segments of the PCR products are then sequence specifically labelled in a cyclic linear signal amplification reaction. This is done both to increase the sensitivity and the specificity of the assay. Hybridisation of the labelled oligonucleotides to their complementary sequences in a DNA array enables multiplex detection. Quantitative information was obtained in the range 0.1-2% for the different GM constructs tested. Seventeen different food and feed samples were screened using a twelve-plex system for simultaneous detection of seven different GM maize events (Bt176, Bt11, Mon810, T25, GA21, CBH351 and DBT418). Ten samples were GM positive containing mainly mixtures of Mon810, Bt11 and Bt176 DNA. One sample contained appreciable amounts of GA21. An eight-plex MQDA-PCR system for detection of Mon810, Bt11 and Bt176 was evaluated by comparison with simplex 5' nuclease PCRs. There were no significant differences in the quantifications using the two approaches. The samples could, by both methods, be quantified as containing >2%, between 1 and 2%, between 0.1 and 1%, or <0.1% in 43 out of 47 determinations. The described method is modular, and thus suited for future needs in GM detection.

Animal Feed↗

PubMed2005

Multiplex PCR: use of heat-stable Thermus thermophilus RecA protein to minimize non-specific PCR products.

In this paper we report that the inclusion of heat-resistant RecA protein from a thermophilic bacteria, Thermus thermophilus, and its cofactor (ATP) in PCR effectively eliminates non-specific PCR products. The effect of RecA protein, which catalyzes pairing between homologous DNA molecules with great fidelity in genetic recombination, is due to its promotion of precise priming in PCR (i.e. priming at sites where the primer sequence is completely complementary to that of the target sequence). In addition, the RecA protein substantially reduces the primer concentration required for PCR. These experimental results have led to the realization of multiplex PCR, which involves PCR for multiple sites in the same reaction mixture. We were able to successfully perform multiplex PCR with over a dozen reactions without affecting the amplification pattern of the PCR products.

Base Pair Mismatch↗

PubMed1997

Demonstration of cytoplasmic tyrosinase mRNA in tissue-cultured cells by reverse transcription (RT) in situ polymerase chain reaction (PCR) and RT PCR in situ hybridization.

To evaluate the specificity and applicability to the study of human tumor cells of the reverse transcription (RT) in situ PCR and RT polymerase chain reaction (PCR) in situ hybridization techniques, we examined five melanoma cell lines and five nonmelanoma lines for tyrosinase mRNA using primers specific for tyrosinase. Each procedural step was optimized and minutely controlled, and results from the in situ techniques and solution-phase RT-PCR were compared. All melanoma lines showed a specific pattern of perinuclear cytoplasmic reaction not seen in nonmelanoma lines. There was exact agreement between the results from the RT in situ PCR and RT-PCR in situ hybridization techniques and those from solution-phase RT-PCR. Ribonuclease digestion abolished cytoplasmic staining, as did omission of the reverse transcriptase step. Nuclear staining was seen in melanoma and nonmelanoma lines, apparently as a result of DNA synthesis from repair-replication and mispriming or nonspecific amplification. Neither high concentrations of deoxyribonuclease nor long incubation periods abolished this effect completely. Demonstration of cytoplasmic mRNA by RT in situ PCR and RT-PCR in situ hybridization specifically identifies cells of melanocytic lineage.

Colonic Neoplasms↗

PubMed2004

Cytomegalovirus infection in organ-transplant recipients: diagnostic value of pp65 antigen test, qualitative polymerase chain reaction (PCR) and quantitative Taqman PCR.

BACKGROUND: The human cytomegalovirus (CMV) is a major cause of morbidity and mortality in transplant patients. In this study, we compared the diagnostic value of pp65 antigen test, qualitative nested polymerase chain reaction (PCR), and quantitative Taqman PCR in predicting the clinical outcome of CMV infection. METHODS: A total of 169 samples derived from 59 organ-transplant recipients (kidney n= 46, liver n= 11, kidney and pancreas n= 2) were analyzed. Peripheral blood leukocytes (PBL) were isolated using dextran gradient centrifugation, and 2 x 10 cells were analyzed for pp65 antigen by immunofluorescence. A crude DNA extract obtained from the same number of cells was used for qualitative nested PCR and quantitative Taqman PCR analysis. RESULTS.: The correlation coefficient of pp65 antigen test and Taqman PCR was R= 0.699 (P = 0.001). With cut-off values for pp65 antigen test set at greater than 10 positive nuclei per 2 x 10 PBL, sensitivity was 91%, and positive predictive value (PPV) was 70%. When the corresponding cut-off value for Taqman PCR was applied (>125000 genome copies per 2 x 10 PBL), a sensitivity of 83% and a PPV of 68% were found. Both assays allowed for the monitoring of successful antiviral therapy. Although qualitative nested PCR was highly sensitive (95%), it was less useful in predicting CMV disease (PPV 47%) and in therapy control. CONCLUSION: Our data show that pp65 antigen test and Taqman PCR are almost equivalent in the monitoring of CMV infection and disease when identical cell numbers are used for both assays.

Adult↗

PubMed1995

Comprehensive, serologically equivalent DNA typing for HLA-B by PCR using sequence-specific primers (PCR-SSP).

Polymorphic products of HLA class I genes from the human major histocompatibility complex (MHC) are traditionally assigned by serology with additional heterogeneity detectable using one-dimensional isoelectric focusing (1D-IEF). With the increased availability of HLA class I DNA sequence information it has become feasible to genotype for class I by polymerase chain reaction utilising sequence-specific primers (PCR-SSP). We describe here a comprehensive HLA-B PCR-SSP typing system based on available HLA nucleotide sequences which can detect all serologically defined antigens in most heterozygous combination in 48 one-step PCR reactions. In addition, four new unsequenced variants have been identified. DNA samples from 57 International Histocompatibility Workshop reference cell lines and 160 control individuals have been typed by the HLA-B PCR-SSP technique. 3/57 cell line types and 12/160 normal control individuals types were discrepant with the reported serological types. The SSP system has been designed to be higher resolution than serology but is not a complete allele-specific PCR although many single alleles can be identified. The system is entirely complementary to previous published PCR-SSP systems for HLA-Class II and HLA-Class I in that the same PCR conditions and controls are used which allows us to do one step PCR-SSP for all relevant HLA loci in under 3 hours in a system suitable for the typing of cadaver donors.

Alleles↗

PubMed2005

Rapid assignment of the swine major histocompatibility complex (SLA) class I and II genotypes in Clawn miniature swine using PCR-SSP and PCR-RFLP methods.

BACKGROUND: Inbred miniature swine with defined novel SLA haplotypes will be useful in allo- and xeno-transplantation studies, which can be carried out representing variable combinations of SLA haplotypes. METHODS: In Clawn miniature swine, two haplotypes (c1 and c2) and one crossover haplotype (c3) have been assigned by nucleotide sequence determination of RT-PCR products of the three SLA classical class I genes and two SLA class II genes. To select SLA class I and II homozygotes in Clawn miniature swine individuals, we developed a rapid and simple SLA-class I- and II-DNA typing method by a combination of polymerase chain reaction-sequence specific primer (PCR-SSP) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) techniques. RESULTS: Seven allele specific primer pairs were designed for amplification of the second exons of three SLA class I genes, SLA-1, SLA-2, and SLA-3, and one SLA class II gene, DRB1. Furthermore, based on PCR-RFLP patterns in the SLA-DQB1 gene, two allelic variants were recognized in the second exon in the Clawn miniature swine. Three haplotypes, c1, c2 and c3, were simply identified by the combination of PCR-SSP and PCR-RFLP methods in 22 samples from five families. A single allele at each of the class I and II genes was also observed in seven samples as SLA class I and II homozygotes with either the c1 or c2 haplotype. CONCLUSIONS: The combination of PCR-SSP and PCR-RFLP methods facilitate the rapid identification of the three haplotypes and SLA class I and II homozygotes in individual Clawn miniature swine.

Alleles↗

PubMed2004

Rapid diagnosis of bacterial meningitis by using multiplex PCR and real time PCR.

BACKGROUND: The purpose of the present study was to improve a method for a rapid identification of bacteria in bacterial meningitis by using multiplex polymerase chain reaction (PCR). METHODS: Ten species of bacteria which cause meningitis in children were investigated, and cerebrospinal fluid from patients with purulent meningitis was studied. The ribosomal RNA genes of bacteria are essential, and are highly conserved in the bacterial kingdoms with consensus region. The 23S rRNA region shows a larger variation among species than in the 16S rRNA region. The authors set primers in the universal region and specific region of 23S rRNA, then amplified these regions by multiplex PCR and real-time PCR. RESULTS: All species of bacteria showed one band by PCR using universal primer. Haemophilus influenzae and Streptococcus pneumoniae showed two bands by multiplex PCR using a combination of universal primers and specific primers. The authors detected H. influenzae within 15 min by using real-time PCR. CONCLUSION: It was possible to identify clinically significant bacterial species in cerebrospinal fluid by multiplex PCR, and to identify H. influenzae by real-time PCR within a short period.

Cerebrospinal Fluid↗

PubMed2002

Detection of duck hepatitis B virus DNA on filter paper by PCR and SYBR green dye-based quantitative PCR.

Duck hepatitis B virus (DHBV) belongs to the Hepadnaviridae family, which includes human Hepatitis B virus (HBV) and Woodchuck hepatitis virus. It is widely distributed in wild and domestic ducks due to congenital transmission. HBV is a worldwide health problem, with carriers at risk of developing cirrhosis and liver cancer. Medical staff and scientists working with HBV must be vaccinated because of its contagious nature. DHBV is a safe surrogate for HBV because of their similarities. Collection of serum and blood samples on filter paper has been used to screen for metabolic disorders, genetic diseases, and viral infection and for evolutionary studies of the genome. In this study, DHBV from serum and blood dried on filters was detected by PCR. A 0.1-microl sample was sufficient for detection. The immobilization potential of filter papers for DHBV was examined, and the highest yield of PCR products was observed with Whatman paper. Dried serum was stable under different storage temperatures for 4 weeks, but the yields of PCR products decreased when the temperature was >or=4 degrees C. The optimal condition for storage was -70 degrees C. A newly developed quantitative PCR based on monitoring the amplification by measuring the increase in fluorescence caused by the binding of SYBR green dye to double-stranded products was applied herein. DHBV genomic DNA cloned in a plasmid was used for the generation of standard DHBV DNA for quantitative PCR. It validated results from PCR in terms of the copy number of DHBV particles. The specificity of PCR was demonstrated by melting curve analysis, and the differentiation of two DHBV isolates amplified from dried serum was demonstrated based on their melting temperatures determined by GC contents and sequence. It was easier and simpler than other PCR-based DNA techniques. The use of serum dried on filters allows samples from distant field for which cold storage and transportation are a problem to be mailed to the diagnostic laboratory. Samples can be archived for comparison and used as a source of DNA for cloning and sequencing.

Animals↗

PubMed2004

Comparison of real-time PCR signal-amplified in situ hybridization and conventional PCR for detection and quantification of human papillomavirus in archival cervical cancer tissue.

Archival paraffin-embedded tumor specimens offer a wealth of information for both cancer research and for routine clinical applications. However, the use of formalin-fixed, paraffin-embedded specimens for quantitative real-time PCR is not yet a standard diagnostic method in many laboratories, in particular for the quantification of human papillomavirus (HPV). Particularly high-risk HPV types are involved in almost 100% of the carcinogenesis of cervical cancer. We compared the diagnostic applicability and sensitivity of real-time PCR to that of chromogenic tyramide-signal-amplified in situ hybridization and conventional PCR for the detection of HPV from archival tissue in 164 cases of carcinoma in situ and cervical cancer. Furthermore, we examined whether the viral load of HPV is of prognostic relevance. Our findings indicate that patients in tumor stage I with a lower viral load of HPV type 16 (HPV16; up to 1,000 copies/ng of DNA) had a significantly better survival than HPV 16-negative patients (P = 0.037). We observed a greater sensitivity of both real-time PCR and conventional PCR for the detection of HPV16 and -18 compared to signal amplified in situ hybridization. We found a considerable concordance between HPV16 (kappa = 0.661) and HPV18 (kappa = 0.781) status as measured by real-time PCR and conventional PCR, indicating similar sensitivities. We recognized an inhibitory effect of formalin fixation and paraffin embedding on the evaluation of real-time PCR quantification.

Base Sequence↗

PubMed2005

Touch-down reverse transcriptase-PCR detection of IgV(H) rearrangement and Sybr-Green-based real-time RT-PCR quantitation of minimal residual disease in patients with chronic lymphocytic leukemia.

BACKGROUND: Patients with chronic lymphocytic leukemia (CLL) can relapse even after aggressive therapy and autografts. It is commonly assumed that to prevent relapse the level of minimal residual disease (MRD) should be as low as possible. To evaluate MRD, highly sensitive quantitative assays are needed. AIM: The aim of the study was to develop a robust and sensitive method for detection of the clonal immunoglobulin heavy-chain variable (IgV(H)) rearrangement in CLL and to introduce a highly sensitive and specific methodology for MRD monitoring in patients with CLL who undergo intensive treatment. METHODS: As a prerequisite for MRD detection, touch-down reverse transcriptase (RT)-PCR using degenerate primers were used for the diagnostic identification of (H) gene rearrangement(s). For quantitative MRD detection in 18 patients, we employed a real-time RT-PCR assay (RQ-PCR) making use of patient-specific primers and the cost-saving Sybr-Green reporter dye (SG). For precise calibration of RQ-PCR, patient-specific IgV(H) sequences were cloned. RESULTS: Touch-down RT-PCR with degenerate primers allowed the successful detection of IgV(H) clonal rearrangement(s) in 252 of 257 (98.1%) diagnostic samples. Biallelic rearrangements were found in 27 of 252 (10.7%) cases. Degenerate primers used for the identification of clonal expansion at diagnosis were not sensitive enough for MRD detection. In contrast, our RQ-PCR assay using patient-specific primers and SG reached the sensitivity of 10(-)(6). We demonstrated MRD in each patient tested, including four of four patients in complete remission following autologous hematopoietic stem cell transplantation (HSCT) and three of three following allogeneic 'mini'-HSCT. Increments in MRD might herald relapse; aggressive chemotherapy could induce molecular remission. CONCLUSIONS: Our touch-down RT-PCR has higher efficiency to detect clonal IgV(H) rearrangements including the biallelic ones. MRD quantitation of IgV(H) expression using SG-based RQ-PCR represents a highly specific, sensitive, and economic alternative to the current quantitative methods.

Benzothiazoles↗

PubMed1999

Multiprobe RNase protection assay with internally labeled radioactive probes, generated by RT-PCR and nested PCR.

RNase Protection Assay (RPAs) is a highly sensitive and reproducible method of quantitating the levels of specific mRNA transcripts. The introduction of the commercially available Multiprobe RPAs allow comparing and quantifying the expression of up to different mRNA species in a single sample of 1-20 micrograms of total RNA. To generate probes which are not commercially available, we prepared highly specific probes by RT-PCR and nested PCR. Then, after ligation of a T7 promoter, another PCR was performed with a primer set consisting of a specific sense primer and antisense T7 primer. Only the antisense strand of the double stranded PCR-product contained the T7-promoter sequence on its 5' end, allowing in vitro transcription and internal labeling with [alpha-32]UTP. Probe concentration was determined in a scintillation counter and equal counts were introduced in the assay. In vitro transcription of the PCR generated probes resulted in radioactive probes with a very high specific activity, allowing simultaneous analysis of 70 different RNA samples. RPA could be performed under the same conditions as recommended for the commercially available probe sets, avoiding time consuming optimization of reaction conditions. Negative controls consisted of yeast RNA and sense RNA probes. Positive controls were single stranded templates, generated by asymmetric PCR. Dilution series revealed a high reproducibility and the potential of this technique to semi-quantitate mRNA in different RNA samples. In conclusion, probes may be generated by RT-PCR and nested PCR that will work with the commercially available Multiprobe RPAs. The high probe yield allows analysis of a great number of samples using the same set of probes with a high reproducibility.

Antigens, CD↗

PubMed2005

Simultaneous detection of listeria monocytogenes in chicken meat enrichments by PCR and reverse-transcription PCR without DNA/RNA isolation.

Environmental and food samples can be analyzed using PCR and reverse transcription (RT)-PCR techniques to discriminate between viable and nonviable cells of bacterial pathogens. Here, we describe the use of a commercial lysis buffer, initially designed for mammalian cells, that permits the rapid extraction of bacterial DNA and RNA. The buffer is an RT-PCR-compatible lysis solution in which RNA is stable and can be frozen for later use. RT-PCR is carried out directly after DNase I treatment of crude bacterial lysates using rTth polymerase for RT-PCR in a single tube. Untreated lysate is used for standard PCR. The procedure permits the amplification of either mRNA or DNA of Listeria monocytogenes at a level similar to that obtained with purified nucleic acids. Using lysates obtained with this buffer, nested PCR and RT-PCR assays detected low numbers of L. monocytogenes cells from artificially contaminated chicken meat samples. The simplicity of this system may foster the development of similar buffers specifically designed for bacteria to improve RNA detection methods that can be performed in parallel with DNA analysis. The use of a single buffer decreases the time needed for analysis, is amenable to automation and real-time assays, and might be adaptable to all bacteria and amplification methods.

Animals↗

PubMed2001

Reverse transcription polymerase chain reaction (RT-PCR) for diagnosis of respiratory syncytial virus infection in adults: use of a single-tube "hanging droplet" nested PCR.

Rapid diagnosis of Respiratory Syncytial virus (RSV) infection is difficult in elderly persons due to the low quantities of virus shed. Therefore, reverse transcription-polymerase chain reaction (RT-PCR) was used to detect viral RNA in respiratory secretions. A single-tube nested RT-PCR that used primers from a conserved F gene sequence was developed using a "hanging droplet" to physically separate outer and inner primer pairs during the first round of the PCR reaction. This was accomplished by placing the inner primers in a 5 microL droplet on the underside on the reaction tube cap and mixing after the first round of PCR. As few as 0.05 pfu of virus could be detected and gave positive results with RSV strains that represented the major groups and subgroups of RSV grown in tissue culture. The nested PCR was approximately 100-fold more sensitive than standard single primer PCR reactions and equivalent to standard two-tube nested PCR. Viral RNA was detected in nasopharyngeal samples from 12 of 15 culture positive illnesses and in 5 of 17 culture-negative, seropositive illnesses despite specimen volumes less than 1 microL in some samples. The method was also positive in 14 of 25 elderly volunteers inoculated with a live attenuated RSV vaccine candidate, only one of whom was culture positive. Use of a nested RT-PCR significantly improves the ability to detect RSV in respiratory samples and should improve the ability to rapidly diagnose RSV infection in adults, especially in the elderly.

Aged↗

PubMed2005

Increasing detection of polymerase chain reaction (PCR) by isolation of PCR products (IPCRp).

AIM: To develop a method for enhanced polymerase chain reaction (PCR) product detection. METHODS: During the PCR, the double-stranded product is generated with fluorescent dye on one strand, and biotin on the other strand. The product is captured on the streptavidin-coated plates with high efficiency (IPCRp). Washing of the all unamplified compounds, including dye-labeled unincorporated primers, follows the PCR. The targeted dye-labeled PCR product is released by denaturation and loaded on the detection platform. RESULTS: After the application of the IPCRp, the resulting product is highly concentrated targeted dye-labeled single-stranded DNA, free of the unincorporated primers and other PCR artifacts. The strength of the signal of the IPCRp product on detection platform is two- to five-fold higher than the strength of the signal of the conventional PCR product. CONCLUSION: The IPCRp procedure can be accomplished in less than 20 minutes. Efficient isolation of the PCR products has two steps, washing and denaturation. It can increase the yield of targeted PCR product and increase the sensitivity of the detection platform.

DNA↗

PubMed2006

Comparison between two real-time PCR assays and a nested-PCR for the detection of Toxoplasma gondii.

BACKGROUND AND AIM OF THE WORK: In recent years, the diagnosis of toxoplasmosis has been improved by Real-time PCR assays. In this study we compared the performances of two Real-time PCRs (FRET and TaqMan protocols) already described in the literature, and one nested-PCR, currently used in our laboratory for the molecular diagnosis of toxoplasmosis. METHODS: We evaluated the sensitivity and the specificity of a FRET- and a TaqMan-based Real-time PCRs targeting a 529 bp repeat region and the 18S RNA gene, respectively, and a nested-PCR, targeting the B1-gene of Toxoplasma gondii. We also tested, through nested-PCR, 46 biological samples obtained during a period of 29 months from pregnant women or immunocompromised patients with suspected T. gondii infection. RESULTS: The analytical sensitivity of nested and TaqMan PCRs was approximately 10(3) tachyzoites/ml. FRET assay showed a sensitivity of 102 tachyzoites/ml. Three out of 46 biological samples were nested-PCR-positive and these results were also confirmed by both Real-time PCRs. CONCLUSIONS: Nested- and real-time PCRs evaluated in this study resulted very sensitive and specific; in particular FRET PCR resulted more sensitive than the other assays, probably because of the greater copy number of the target sequence. Real-time PCR assays are easy-to-use, producing results faster than conventional PCR systems and reducing contamination risks.

Adult↗

PubMed1994

[Comparison of histology, immunohistochemistry, RT-PCR, in situ hybridization, and in situ RT-PCR for demonstration of hepatitis C virus in paraffin-embedded liver biopsies].

To compare immunohistochemical and molecular methods for the detection of hepatitis C virus (HCV) infection in archival liver biopsies we analyzed formalin-fixed and paraffin-embedded liver specimens of 10 patients with serologically confirmed HCV infection. Methods employed included indirect FITC-immunofluorescence, reverse-transcriptase polymerase chain reaction (RT-PCR) using extracted RNA and Southern blotting with chemiluminescence-based detection, non-radioactive in situ hybridization (ISH) with digoxigenin-labeled oligo- and cRNA probes, direct in situ RT-PCR with incorporation of labeled nucleotides into PCR-products, and indirect in situ RT-PCR using subsequent ISH for the visualization of intracellular PCR-products. Our results indicate that: (1) using the histological criteria described by Lefkowitch et al. (Gastroenterology 1993; 104-595) together with clinical data, most chronic HCV infections can be diagnosed by conventional histology, if liver biopsies are representative; (2) the commercially available mAB TORDJI-22 appears to cross-react with non-HCV epitopes; (3) molecular methods performed on routinely fixed and processed liver biopsies frequently yield false negative results due to sampling problems, low viral copy number and RNA degradation in infected cells; (4) analysis of HCV-RNA by RT-PCR of extracted total RNA is more sensitive than indirect in situ RT-PCR or ISH; and (5) direct in situ RT-PCR is not reliable despite the use of modifications such as DNase pretreatment and hot-start procedures. Further studies are required to define both optimal methods for sample processing and improvements of protocols, in order to increase detection sensitivity and specificity of HCV infection by immunohistochemical and molecular methods.

Biopsy↗

PubMed2001

State of HBV DNA in HBsAg-negative, anti-HCV-positive hepatocellular carcinoma: existence of HBV DNA possibly as nonintegrated form with analysis by Alu-HBV DNA PCR and conventional HBV PCR.

The role of hepatitis B virus (HBV) in carcinogenesis of hepatitis B surface antigen (HBsAg)-negative, anti-hepatitis C virus (anti-HCV)-positive hepatocellular carcinoma (HCC) remains unknown. To investigate the state of HBV DNA in such HCC, HBV DNA was examined by polymerase chain reaction (PCR) between HBV DNA and human Alu sequence (HBV-Alu PCR), which could detect integrated form of HBV DNA only, and by conventional HBV PCR, which could detect both integrated and episomal forms of HBV DNA. In all the 17 HBsAg-positive HCC, HBV DNA was detected by both HBV-Alu PCR method and conventional HBV PCR method. By contrast, in HBsAg-negative, anti-HCV-positive cases, HBV DNA was detected in 10 of 21 (47.6%) by conventional HBV PCR and in none of 21 (0%) by HBV-Alu PCR method. Thus, integrated form of HBV DNA was not found in most HbsAg-negative, anti-HCV-positive HCC in the current study. The role of episomal form of HBV DNA requires further investigation of its involvement in the process of the development of HBsAg-negative, anti-HCV-positive HCC.

Adult↗

PubMed1996

Cloning of murine LAG-3 by magnetic bead bound homologous probes and PCR (gene-capture PCR).

In recent years PCR-based gene cloning strategies have found wide application in molecular biology, due to the power, speed, and relative simplicity of the PCR methodology. We have set up a novel PCR cloning strategy to isolate homologous genes, which is based on the capture of the cDNA sequence(s) of interest with a biotinylated probe and streptavidin-coupled magnetic beads followed by PCR amplification of the selected molecules. This method does not require sequence information on 5' and 3' regions of the cDNA of interest and permits gene isolation to be sensitive, fast, simple, and specific even when the conventional screening procedures give rise to high backgrounds. By using this technique, which we propose to call gene-capture PCR (GC-PCR) cloning, we were able to isolate the full-length murine lymphocyte activation gene 3 (LAG-3) cDNA from total RNA of activated thymocytes. The GC-PCR technique represents a powerful tool for easy isolation not only of homologous genes from related species, but also of genes sharing conserved regions of suitable length, gene variants, and gene encoding proteins where only limited knowledge of the amino acid sequence exists.

Amino Acid Sequence↗