One-step Real-time Reverse Transcription-polymerase Chain Reaction Research Articles

ƩS COVID-19 is a rapid high throughput and sensitive one-step quadruplex real-time RT-PCR assay

Real-time reverse transcription polymerase chain reaction (RT-PCR), a standard method recommended for the diagnosis of coronavirus disease 2019 (COVID-19) requires 2–4 h to get the result. Although antigen test kit (ATK) is used for COVID-19 screening within 15–30 min, the drawback is its limited sensitivity. Hence, a rapid one-step quadruplex real-time RT-PCR assay: termed ƩS COVID-19 targeting ORF1ab, ORF3a, and N genes of SARS-CoV-2; and Avocado sunblotch viroid (ASBVd) as an internal control was developed. Based on strategies including designing high melting temperature primers with short amplicons, applying a fast ramp rate, minimizing hold time, and reducing the range between denaturation and annealing/extension temperatures; the assay could be accomplished within 25 min. The limit of detection of ORF1ab, ORF3a, and N genes were 1.835, 1.310, and 1 copy/reaction, respectively. Validation was performed in 205 combined nasopharyngeal and oropharyngeal swabs. The sensitivity, specificity, positive predictive value, and negative predictive value were 92.8%, 100%, 100%, and 97.1%, respectively with 96.7% accuracy. Cohen’s Kappa was 0.93. The newly developed rapid real-time RT-PCR assay was highly sensitive, specific, and fast, making it suitable for use as an alternative method to support laboratory diagnosis of COVID-19 in outpatient and emergency departments.

Integrating Magnetic-Bead-Based Sample Extraction and Molecular Barcoding for the One-Step Pooled RT-qPCR Assay of Viral Pathogens without Retesting.

Pooling multiple samples prior to real-time reverse-transcription polymerase chain reaction (RT-PCR) analysis has been proposed as a strategy to minimize expenses and boost test throughput during the COVID-19 pandemic. Nevertheless, the traditional pooling approach cannot be effectively deployed in high-prevalence settings due to the need for secondary tests in the case of a positive pool. In this study, we present a pooling test platform with high adaptability and simplicity that allows sample-specific detection of multiple-tagged samples in a single run without the need for retesting. This was accomplished by labeling distinct samples with predefined ID-Primers and identifying tagged pooled samples using one-step RT-PCR followed by melting curve analysis with rationally designed universal fluorescence- and quencher-tagged oligo probes. Using magnetic beads (MBs), nucleic acid targets from different individuals can be tagged and extracted concurrently and then pooled before RT, eliminating the need for extra RNA extraction and separate RT and enzyme digestion steps in the recently developed barcoding strategies. Pools of six samples (positive and negative) were successfully identified by melting temperature values under two fluorescent channels, with a detection sensitivity of 5 copies/μL. We validated the reproducibility of this assay by running it on 40 clinical samples with a hypothetical infection rate of 15%. In addition, to aid the scenario of large-scale pooling tests, we constructed a melting curve autoreadout system (MCARS) for statistical analysis of melting curve plots to eliminate error-prone manual result readout. Our results suggest that this strategy could be a simple and adaptable tool for alleviating existing bottlenecks in diagnostic pooling testing.

Genetic diversity of porcine reproductive and respiratory syndrome virus and evaluation of three one-step real-time RT-PCR assays in Korea

BackgroundPorcine reproductive and respiratory syndrome virus (PRRSV) has caused huge economic losses in the global swine industry. Frequent genetic variations in this virus cause difficulties in controlling and accurately diagnosing PRRSV.MethodsIn this study, we investigated the genetic characteristics of PRRSV-1 and PRRSV-2 circulating in Korea from January 2018 to September 2021 and evaluated three one-step real-time reverse transcription polymerase chain reaction (RT-PCR) assays.ResultsA total of 129 lung samples were collected, consisting of 47 samples for PRRSV-1, 62 samples for PRRSV-2, and 20 PRRSV-negative samples. Nucleotide sequence analysis of open reading frames (ORFs) 5, ORF6, and ORF7 genes from PRRSV samples showed that PRRSV-1 belonged to subgroup A (43/47, 91.49%) and subgroup C (4/47, 8.51%), whereas PRRSV-2 was classified as lineage 1 (25/62, 40.32%), Korean lineage (Kor) C (13/62, 20.97%), Kor B (10/62, 16.13%), lineage 5 (9/62, 14.52%), and Kor A (5/62, 8.06%). Amino acid sequence analysis showed that the neutralizing epitope and T cell epitope of PRRSV-1, and the decoy epitope region and hypervariable regions of PRRSV-2 had evolved under positive selection pressure. In particular, the key amino acid substitutions were found at positions 102 and 104 of glycoprotein 5 (GP5) in some PRRSV-2, and at positions 10 and 70 of membrane protein (M) in most PRRSV-2. In addition, one-step real-time RT-PCR assays, comprising two commercial tests and one test recommended by the World Organization for Animal Health (OIE), were evaluated.ConclusionThe results revealed that two of the real-time RT-PCR assays had high sensitivities and specificities, whereas the real-time RT-PCR assay of the OIE had low sensitivity due to mismatches between nucleotides of Korean PRRSVs and forward primers. In this study, we genetically characterized recent PRRSV occurrences and evaluated three one-step real-time RT-PCR assays used in Korea.

Surveillance of dengue virus in individual Aedes aegypti mosquitoes collected concurrently with suspected human cases in Tarlac City, Philippines

BackgroundVector control measures are critical for the prevention and reduction of dengue virus (DENV) transmission. Effective vector control is reliant not only on knowledge of mosquito abundance, but also on the timely and accurate detection of mosquito-borne infection. Mosquito-based virus surveillance programs typically rely on pool-based mosquito testing, although whether individual-based mosquito testing is a feasible alternative to this has not been widely studied. Applying an individual-based mosquito testing approach, we conducted a 1-month surveillance study of DENV in adult Aedes aegypti mosquitoes in homes of suspected dengue patients during the 2015 peak dengue season in Tarlac City, Philippines to more accurately assess the mosquito infection rate and identify the DENV serotypes and genotypes concurrently co-circulating in mosquitoes and patients there.MethodsWe performed a one-step multiplex real-time reverse transcription-polymerase chain reaction (RT-PCR) assay for the simultaneous detection and serotyping of DENV in patients and individual female Ae. aegypti mosquitoes. Additionally, we performed sequencing and phylogenetic analyses to further characterize the detected DENV serotypes in mosquitoes and patients at the genotype level.ResultsWe collected a total of 583 adult Ae. aegypti mosquitoes, of which we individually tested 359 female mosquitoes for the presence of DENV. Ten (2.8%) of the 359 female mosquitoes were positive for the presence of DENV. We detected DENV-1, DENV-2, and DENV-4 in the field-collected mosquitoes, which was consistent with the serotypes concurrently found in infected patients. Sequencing and phylogenetic analyses of the detected DENV serotypes based on the partial sequence of the evelope (E) gene revealed three genotypes concurrently present in the sampled mosquitoes and patients during the study period, namely DENV-1 genotype IV, DENV-2 Cosmopolitan genotype, and DENV-4 genotype II.ConclusionsWe demonstrated the utility of a one-step multiplex real-time RT-PCR assay for the individual-based DENV surveillance of mosquitoes. Our findings reinforce the importance of detecting and monitoring virus activity in local mosquito populations, which are critical for dengue prevention and control.

Development of a multiplex one-step real-time RT-PCR assay for the simultaneous detection of eight viruses associated with febrile rash illnesses

Fever and rash illnesses (FRIs) are a series of common diseases with fever and rashes as clinical manifestations, most of which are caused by viral infection. The rashes of FRIs are generally nonspecific; therefore it is difficult to identify FRI-associated viruses solely based on clinical symptoms. To achieve rapid and accurate identification of FRI pathogens, a multiplex one-step real-time reverse transcription-polymerase chain reaction (RT-PCR) assay was developed and evaluated in this study. Primers and probes were selected for the detection of measles virus (MeV), rubella virus (RV), human enterovirus (EV), varicella-zoster virus (VZV), dengue virus (DENV), human parvovirus B19 (B19), Epstein-Barr virus (EBV), and human herpes virus 6 (HHV-6), which cover the most common pathogenic viruses of FRIs. Detection of the eight FRI-associated viruses, which was divided into two groups/tubes, was simultaneously performed under universal optimized reaction conditions in multiplex one-step real-time RT-PCR assay. The multiplex real-time RT-PCR showed high sensitivity and specificity in detecting the eight FRI-associated viruses. The limits of detection (LODs) for the eight viruses were in the range of 47–177 copies/reaction, and no cross reactions for the eight FRI-associated viruses were found in the multiplex assay. In addition, the results of the multiplex real-time RT-PCR assay were consistent with the results of a monoplex real-time RT-PCR assay and sequencing for clinical specimens obtained from FRI patients. With its advantages of high efficiency and rapid and accurate diagnosis, multiplex real-time RT-PCR was very feasible for the early diagnosis of FRI pathogenic viruses and would be of great help for the proper treatment, monitoring, and initiation of preventive measures for FRI cases.

A one-step real-time RT-PCR helps to identify mixed rotavirus infections in Mexico

Rotaviruses continue being the most important pathogens responsible of diarrhea in young children worldwide. Seminested reverse transcription polymerase chain reaction (RT-PCR) is used to determine rotavirus genotype; however, this technique employs multistep procedures. The real-time RT-PCR is a fast and reliable tool that can be used as rotavirus genotyping tool, especially in rotavirus outbreaks. In this study, we tested a real-time RT-PCR to identify rotavirus genotype using a panel of 252 samples from patients with diarrheal disease caused by G9P[4] and G12P[8] genotypes, which were identified as emerging rotaviruses in 2 outbreaks in Chiapas, Mexico. Our results show that the real-time RT-PCR assay detected these rotaviruses, and it allowed us to identify mixed genotype infections, G/P combinations, and the viral abundance in some samples in which the seminested assay could not identify them. Therefore, the real-time RT-PCR is a molecular tool that can be great support during rotavirus outbreaks.

Internal control for real-time polymerase chain reaction based on MS2 bacteriophage for RNA viruses diagnostics.

BACKGROUND Real-time reverse transcription polymerase chain reaction (RT-PCR) is routinely used to detect viral infections. In Brazil, it is mandatory the use of nucleic acid tests to detect hepatitis C virus (HCV), hepatitis B virus and human immunodeficiency virus in blood banks because of the immunological window. The use of an internal control (IC) is necessary to differentiate the true negative results from those consequent from a failure in some step of the nucleic acid test.OBJECTIVES The aim of this study was the construction of virus-modified particles, based on MS2 bacteriophage, to be used as IC for the diagnosis of RNA viruses.METHODS The MS2 genome was cloned into the pET47b(+) plasmid, generating pET47b(+)-MS2. MS2-like particles were produced through the synthesis of MS2 RNA genome by T7 RNA polymerase. These particles were used as non-competitive IC in assays for RNA virus diagnostics. In addition, a competitive control for HCV diagnosis was developed by cloning a mutated HCV sequence into the MS2 replicase gene of pET47b(+)-MS2, which produces a non-propagating MS2 particle. The utility of MS2-like particles as IC was evaluated in a one-step format multiplex real-time RT-PCR for HCV detection.FINDINGS We demonstrated that both competitive and non-competitive IC could be successfully used to monitor the HCV amplification performance, including the extraction, reverse transcription, amplification and detection steps, without compromising the detection of samples with low target concentrations. In conclusion, MS2-like particles generated by this strategy proved to be useful IC for RNA virus diagnosis, with advantage that they are produced by a low cost protocol. An attractive feature of this system is that it allows the construction of a multicontrol by the insertion of sequences from more than one pathogen, increasing its applicability for diagnosing different RNA viruses.

An outbreak of influenza A(H3N2) in Alappuzha district, Kerala, India, in 2011.

Influenza is an RNA virus that belongs to the Orthomyxoviridae family. It causes a highly contagious acute respiratory illness, has been recognized since ancient times, and is a major health threat throughout the world. An outbreak of influenza-like illness (ILI) was reported from Alappuzha district of Kerala State between late June and July 2011. This investigation was conducted to determine the clinical picture, causative agents, and epidemiological characteristics of the illness. The World Health Organization (WHO)'s case definition for ILI was followed throughout the investigation. Nasal or throat swabs were collected from 204 suspected patients. Real-time reverse transcription polymerase chain reaction (RT-PCR)-based diagnosis was performed to detect influenza A and B viruses and their subtypes. Madin-Darby canine kidney (MDCK) cell line was used for virus isolation. One-step RT-PCR was performed to amplify the HA1 gene of influenza A(H3N2). The amplicons for the HA1 gene of influenza A(H3N2) were sequenced, and phylogenetic analysis was done. Analysis of the data revealed that 96 (47.05%) of the 204 respiratory specimens collected were influenza A(H3N2) and only 6 (2.94%) were A(H1N1)pdm09. Phylogenetic analysis revealed that the isolated A(H3N2) was closely related to the 2012-2013 northern hemisphere vaccine strain (A/Victoria/361/2011/H3N2). An influenza A(H3N2) outbreak was confirmed in Alappuzha district of Kerala state with a co-circulation of A(H1N1)pdm09. No substantial difference in the sequence was observed in the etiological agent, and the virus was found to be sensitive to oseltamivir.

Development and Validation of One-Step SYBR Green Real-Time RT-PCR for the Rapid Detection of Newly Emerged Duck Tembusu Virus

Duck Tembusu virus (DTMUV) is a single-stranded positive-sense RNA virus that causes disease to emerge in duck flocks and results in huge economic losses to the duck industry. However, no vaccines and control measures are available in China to date. Development of reliable and fast detection methods is necessary to prevent and control this disease. Therefore, a one-step SYBR Green real-time reverse transcription polymerase chain reaction (RT-PCR) method is established here for DTMUV detection. The results show that the method can specifically detect DTMUV without cross-reactions with selected avian pathogens. The sensitivity of the assay was 1000 times greater than that of a conventional RT-PCR and able to test as few as 20 copies from RNA standard samples. The coefficients of variations of inter- and intra-assay values ranged from 0.09% to 0.36% and 0.1% to 0.23%, respectively. Testing 168 field samples and 96 experimentally infected samples by conventional RT-PCR and the one-step SYBR Green real-time RT-PCR, the positive rates were 35.1% and 73.8% from field samples and 30.2% and 64.6% from infected samples. The one-step SYBR Green real-time RT-PCR developed in this study was shown to be a sensitive, specific, high-throughput, cost-effective, and simple diagnostic tool for the rapid detection and epidemiological surveillance of the emerging DTMUV infection.

Development of one-step SYBR Green real-time RT-PCR for quantifying bovine viral diarrhea virus type-1 and its comparison with conventional RT-PCR

BackgroundBovine viral diarrhea virus (BVDV) is a worldwide pathogen in cattle and acts as a surrogate model for hepatitis C virus (HCV). One-step real-time fluorogenic quantitative reverse transcription polymerase chain reaction (RT-PCR) assay based on SYBR Green I dye has not been established for BVDV detection. This study aims to develop a quantitative one-step RT-PCR assay to detect BVDV type-1 in cell culture.ResultsOne-step quantitative SYBR Green I RT-PCR was developed by amplifying cDNA template from viral RNA and using in vitro transcribed BVDV RNA to establish a standard curve. The assay had a detection limit as low as 100 copies/ml of BVDV RNA, a reaction efficiency of 103.2%, a correlation coefficient (R2) of 0.995, and a maximum intra-assay CV of 2.63%. It was 10-fold more sensitive than conventional RT-PCR and can quantitatively detect BVDV RNA levels from 10-fold serial dilutions of titrated viruses containing a titer from 10-1 to 10-5 TCID50, without non-specific amplification. Melting curve analysis showed no primer-dimers and non-specific products.ConclusionsThe one-step SYBR Green I RT-PCR is specific, sensitive and reproducible for the quantification of BVDV in cell culture. This one-step SYBR Green I RT-PCR strategy may be further optimized as a reliable assay for diagnosing and monitoring BVDV infection in animals. It may also be applied to evaluate candidate agents against HCV using BVDV cell culture model.

Cross-platform evaluation of commercial real-time reverse transcription PCR master mix kits using a quantitative 5′nuclease assay for Ebola virus

Selection of optimal reaction master mix reagents is essential to obtain the best performance with diagnostic real-time reverse transcription polymerase chain reaction (RT-PCR) assays. Every year the number of commercially available master mix kits increases, so it is prudent to periodically evaluate kits on the market. In this study we evaluated five commercial real-time RT-PCR master mix kits, the RealMasterMix RT-PCR ROX kit, the AgPath-ID One-Step RT-PCR kit, the SuperScript III Platinum One-step Quantitative RT-PCR system, the QuantiTect Probe RT-PCR kit, and the LightCycler RNA HybProbe amplification kit, using a 5′nuclease assay for Ebola virus. The kits were evaluated using the manufacturer’s recommended conditions, as well as conditions which have been used with the Ebola virus assay during outbreaks. When evaluated for use in Ebola virus RNA detection, the AgPath-ID kit resulted in the greatest sensitivity in comparison to the other four kits. The efficacy of the AgPath-ID kit was instrument-independent in the five real-time PCR platforms tested. This study demonstrated that Ebola virus RNA detection was not equivalent among the master mix reagents studied and, thus, that this variable can affect real-time RT-PCR assay sensitivity. Furthermore, this study rates the master mix reagents for their suitability, providing diagnostic laboratories the option to select from these kits to suit their specific laboratory needs for real-time RT-PCR.

Development of a method for the detection of infectious myonecrosis virus by reverse‐transcription loop‐mediated isothermal amplification and nucleic acid lateral flow hybrid assay

We report the development of a reverse-transcription loop-mediated isothermal amplification and nucleic acid lateral flow method (RT-LAMP-NALF) for detection of infectious myonecrosis virus (IMNV). The RT-LAMP-NALF method combines simplified nucleic acid extraction, a reverse-transcription loop-mediated isothermal amplification platform, and one-step visual colorimetric confirmation of the IMNV amplified sequences using a generic NALF qualitative detection test strip. The sensitivity of RT-LAMP (using two and three primer pairs) and nested RT-LAMP (using three primer pairs) was compared by real-time reverse-transcription-polymerase chain reaction (RT-PCR) using TaqMan probe. The detection of RT-LAMP (three primer pairs) products was accomplished by using a NALF-test strip. The RT-LAMP-NALF showed equivalent sensitivity to RT-LAMP (using three primer pairs), and it was found to be 100 and 10 times more sensitive than one-step RT-PCR and RT-LAMP (two primer pairs), respectively. On the other hand, the RT-LAMP-NALF was 10 and 100 times less sensitive than nested RT-PCR and real-time RT-PCR, respectively. The simplified RNA extraction method ranged from 4.4 x 10(6) to 2.2 x 10(8) IMNV copy numbers microL(-1) RNA, and it was similar with the standard RNA extraction (from 1.2 x 10(6) to 6.3 x 10(7) IMNV copy numbers microL(-1) RNA). These results clearly demonstrate that the RT-LAMP-NALF method is specific, sensitive, can shorten the time for analysis, and has potential application for IMNV diagnosis in resource-poor diagnostic settings.

Development of a sensitive and quantitative assay for spring viremia of carp virus based on real-time RT-PCR

A one-step real-time reverse transcription-polymerase chain reaction (RT-PCR) using a TaqMan probe to quantitatively detect spring viremia of carp virus (SVCV) is described. In this assay, a pair of primers amplifying an 81-bp DNA fragment and a TaqMan probe was designed targeting the conserved region at the SVCV glycoprotein ( G) gene. To avoid the disadvantages arising from plasmids, an extension adding a T7 phage polymerase promoter to the 5′ end of the antisense primer was carried out to obtain viral cRNA. Standardized cycle threshold (Ct) values for 10-fold serial dilutions of SVCV cRNA were achieved by real-time RT-PCR and used to create standard curves. A regression line between the mean Ct values and viral template concentrations over a 1:10 7 dilution range with an r 2 value (0.9916) and a slope (−3.36) and the coefficient of variation (intra- or inter-assay is <2% and <4%, respectively) indicated that the assay was highly reproducible. The assay was specific to SVCV and there was no cross-reactivity with other fish viruses (viral hemorrhagic septicemia virus, VHSV; infectious pancreatic necrosis virus, IPNV; grass carp reovirus, GCRV; epizootic haematopoietic necrosis virus, EHNV). The standard curve allows precise absolute quantitation and shows that the detection limit of the assay is 40 copies of the viral RNA. This one-step RT-PCR assay was evaluated using 60 clinical common carp samples collected during the year 2006, indicating such technology offers considerable advantages over conventional RT-PCR methods in current routine use for SVCV surveillance. This is the first report of the development of a one-step TaqMan ® RT-PCR for SVCV detection.

Comparison of different molecular methods for assessment of equine arteritis virus (EAV) infection: A novel one-step MGB real-time RT-PCR assay, PCR-ELISA and classical RT-PCR for detection of highly diverse sequences of Slovenian EAV variants

In the present study, a new one-step real-time reverse transcription-polymerase chain reaction (RT-PCR) strategy with minor-groove-binder (MGB) technology for the detection of EAV from 40 semen samples of Slovenian carrier stallions was tested. A novel MGB probe (EAVMGBpr) and a reverse primer (EAV-R) based on the multiple sequence alignment of 49 different EAV strain sequences of the highly conserved ORF7 (nucleocapsid gene) were designed. The performance of the assay was compared with different molecular detection methods. Three different primer pairs targeting the ORF1b and ORF7 were used, respectively. The real-time RT-PCR assay was at least 2 log 10 more sensitive than the classical RT-PCR and at least 1 log 10 more sensitive than the primer set used in the semi-nested PCR. The specificities of the amplification reactions were confirmed with biotinylated probes in the PCR-enzyme-linked immunosorbent assay (PCR-ELISA). Under the conditions described in our study, the sensitivity of the real-time RT-PCR was found to be superior to the PCR-ELISA assay. Thus, while the PCR-ELISA method was found to be both relatively demanding and time consuming, better sensitivity coupled with high specificity and speed of the assay makes the real-time RT-PCR a valuable tool for diagnosis of EAV infection.

Development of a one-step immunocapture real-time TaqMan RT-PCR assay for the broad spectrum detection of Pepino mosaic virus

A real-time reverse-transcription polymerase chain reaction (RT-PCR) was developed for efficient detection of genetically diverse Pepino mosaic virus (PepMV) isolates. The novel detection system was designed to use a duo-primer system targeting the conserved region in the triple gene block 2 (TGB2) gene with a single conserved TaqMan™ probe to broaden its reaction to cover all available PepMV strains. This duo-primer real-time RT-PCR assay was evaluated against US1, US2, Ch1, Ch2 and 25 field isolates collected from six major commercial tomato greenhouse facilities in U.S. and Canada in 2006. Under optimum reaction conditions, sensitivity of the detection was as low as 100 fg of purified viral RNA. This assay was also evaluated for its efficiency in detecting PepMV in various levels of contaminated seed samples. Using immunocapture sample preparation, real-time RT-PCR was able to detect PepMV in one infested seed in 1000. This level of sensitivity indicated that the one-step immunocapture duo-primer TaqMan™ real-time RT-PCR developed in the present study could be used for routine seed health assays.

Rapid and quantitative detection of mumps virus RNA by one-step real-time RT-PCR

We developed a new TaqMan-based one-step real-time reverse transcription-polymerase chain reaction (RT-PCR) assay for detection and quantification of mumps virus RNA. Oligos targeting the matrix protein gene of mumps virus were designed by using our oligo designing and analyzing software, Oligoware 1.0. Oligos's specificity was tested with 5 strains (4 laboratory isolated and 1 Jeryl Lynn strain) of mumps virus. The suggested TaqMan-based one-step real-time RT-PCR assay correctly detected the 4 laboratory-isolated strains and 1 Jeryl Lynn strain. To confirm the specificity of the TaqMan PCR assay, parainfluenza type 1, 2, 3 strains, sendai virus, and measles virus (vaccine strain) were tested, and no cross-reactivity was observed between mumps and tested strains. In addition, a BLAST (NCBI) search showed no genomic cross-reactivity with other viruses or cells. Testing of the assay's reproducibility was repeated several times, and the same results were achieved. The new assay was able to quantify the concentrations of mumps virus gene ranging from 10 1 to 10 8 copies per reaction sensitively with generated plasmid standards. In addition, it was shown that a significant correlation ( R 2 = 0.9564) between genome number as determined by one-step real-time RT-PCR and the corresponding number of plaque in paired samples was found with regression analysis. The results of one-step real-time RT-PCR assay also corresponded well to those of nested PCR. We conclude that our one-step real-time RT-PCR assay is a reliable, specific, and sensitive tool for the diagnosis of mumps virus. We consider that these results come from highly conserved primers and probe set that were designed with Oligoware 1.0.

HEPN1, a novel gene that is frequently down-regulated in hepatocellular carcinoma, suppresses cell growth and induces apoptosis in HepG2 cells

Background/Aims: Examining genes associated with human hepatocellular carcinoma (HCC) by subtractive hybridisation, we identified a novel transcript, designated as HEPN1, in non-tumorous liver. In this study, we aimed to evaluate HEPN1 gene expression in HCC patients, to characterise and to explore the functional significance of HEPN1 in vitro. Methods: One-step reverse transcription-polymerase chain reaction (RT-PCR) and real-time RT-PCR were employed to determine HEPN1 expression in 23 paired (HCC and the adjacent non-HCC) liver specimens. Sequence analyses were performed by bioinformatics. Transfection studies were carried out by expressing HEPN1, V5-fused HEPN1, and green fluorescent protein-fused HEPN1, individually, in HepG2 cells. Results: Significant downregulation of HEPN1 ( P<0.0001) was detected in 22/23 of HCC patients tested. Gene HEPN1 maps to chromosome 11q24.2; and the predicted gene product, a 10-kDa peptide with 88 amino acids, has no homology to known proteins. When transfected into HepG2 cells, HEPN1 reduced cell viability to 37.5±2.5% ( P=0.001), and induced apoptosis with typical morphological changes as demonstrated by microscopy and Annexin V assay. Conclusions: Our data show that HEPN1 is frequently silenced in HCC, and that exogenous HEPN1 exhibits antiproliferative effect on HepG2 cells, suggesting that silencing of HEPN1 may be associated with carcinogenesis of hepatocytes.

Establishment of a rapid procedure for one-step real-time reverse transcription-polymerase chain reaction in combination with automated mRNA extraction: a clinical application to intra-operative molecular diagnosis of cancer cells

Reverse transcription-polymerase chain reaction (RT-PCR) technique is extremely useful for sensitive detection of cancer cells, but it requires at least 8 h. If the precise information on the cancer spread based on RT-PCR is available during surgery, we can give the optimal therapy to each patient during operation. We aimed to establish the ultra-rapid procedure of RT-PCR for application to the intra-operative diagnosis. We have established a one-step real-time RT-PCR using LightCycler with hybridization probes, in combination with automated mRNA extraction on MagNA Pure LC. The method can be completed in only 70 min after sampling and has a comparable sensitivity to conventional RT-PCR and/or two-step real-time RT-PCR with a wide (10–10 6) dynamic range. When this method was applied to the intra-operative detection of free cancer cells in peritoneal lavage, the results were available during operation in all cases. We could detect cancer cells more effectively compared to conventional cytology and RT-PCR. This protocol is easily accomplished, delivers rapid, sensitive and reproducible results, and is therefore applicable to intra-operative diagnosis.