BACKGROUND: Real-time PCR has been widely used not only for quantification?of disease-related genes but also for detection of bacteria or viruses. In this study, we evaluated the performance of Artus HBV LC PCR kit (Qiagen, Hilden, Germany) using recently developed SLAN real-time PCR detection system (Shanghai Hongshi Medical Technology Co., Shanghai, China) to assess clinical relevance of the new instrument. METHODS: Precision, linearity and detection limit of Artus HBV LC PCR kit were evaluated using SLAN real-time PCR detection system. We also compared the SLAN real-time PCR detection system with LightCycler 1.5 (Roche Molecular System, Branchburg, NJ, USA) and ABI PRISM 7500 (Applied Biosystems, Foster City, CA, USA). WHO International Standard for HBV DNA Nucleic Acid Amplification Techniques (NIBSC code:97/750) and 40 HBV DNA positive sera were tested for this evaluation. RESULTS: Within-run and between-day coefficients of variation were 5.63%, 4.01% at 6.2x10(3) IU/mL and 1.12%, 0.80% at 2.1x10(1) IU/mL, respectively. Linearity was verified from 1.0x10(1) to 1.0x10(5) IU/mL (r(2)=1.000; slope=1.1412). Detection limit for HBV DNA was verified to be 7.54 IU/mL. It showed a good correlation with LightCycler 1.5 (r=0.9723) and ABI PRISM 7500 (r=0.9768). CONCLUSIONS: Artus HBV LC PCR kit using SLAN real-time PCR detection system showed a good precision, linearity and assay sensitivity. It correlated well with LightCycler 1.5 and ABI PRISM 7500. We conclude that it can be used in clinical laboratories for nucleic acid quantification.
Bacteria ; DNA ; Limit of Detection ; Nucleic Acid Amplification Techniques ; Polymerase Chain Reaction ; Real-Time Polymerase Chain Reaction

OBJECTIVETo establish the reverse transcription loop-mediated isothermal amplification (RT-LAMP) methods for on-site HIV-1 detection.

METHODSAs for the real-time fluorescent RT-LAMP, we firstly tested the specificity and sensitivity, then explored its quantitative determination, and finally applied the method to the detection of 35 HIV-1 positive samples. For colorimetric judgment, after choosing different ameliorates to modify Hydroxynaphthol blue (HNB), we tested their real effects on coloration, and then picked out the modified dyes with obvious color change to test the sensitivity and the detection of the 35 HIV-1-positive samples.

RESULTSThe real-time fluorescent RT-LAMP showed great specificity of HIV-1, and the sensitivity to detect HIV-1 RNA was between 10 and 100 copies per reaction. On testing 35 HIV-1-positive samples, the method could reach 100 percent detection rate. However, for the quantitative determination, the quantitative relation was not observed regarding the HIV-1 RNA of below 10(3) copies per reaction. Three modified HNB dyes with clear color variation between the reaction tubes of the negative and the positive were got in the study, and their sensitivities equaled to the level of agarose gel electrophoresis. Similarly, 100% (35/35) detection rate was reached when the colorimetric RT-LAMP with the modified dyes was applied to detect 35 HIV-1-positive samples.

CONCLUSIONThe established real-time fluorescence method and the modified color judgment of RT-LAMP could be helpful for truly achieving rapid, accurate, and sensitive on-site detection of HIV-1.

HIV-1 ; genetics ; isolation & purification ; Nucleic Acid Amplification Techniques ; methods ; Reverse Transcriptase Polymerase Chain Reaction

BACKGROUND: The Anyplex plus MTB/NTM and MDR-TB Detection kits (Seegene, Korea) a real-time PCR assays for direct detection of Mycobacterium tuberculosis (MTB) and nontuberculous mycobacteria (NTM) and for identification of rifampin (RIF) and isoniazid (INH) resistance of MTB in various specimens. We evaluated the diagnostic performance of the Anyplex plus MTB/NTM and MDR-TB Detection kit. METHODS: To determine the ability of the kit to detect MTB and NTM, 557 samples were tested. The diagnostic performance of the Anyplex plus MTB/NTM Detection kit was determined based on the results of culture, nucleic acid amplification tests (NAAT), radiologic analysis, and clinical features suggestive of mycobacterial infection. The performance of the kit was compared with those of other real-time PCR kits. For the drug susceptibility test (DST), 51 MTB isolates were tested. The diagnostic performance of the Anyplex plus MDR-TB Detection kit was determined based on the conventional DST and compared with other molecular DST kits. RESULTS: Sensitivity and specificity for MTB detection of the Anyplex plus MTB/NTM Detection kit were 82.9% (63/76) and 99.4% (478/481), respectively, while those for NTM detection were 76.5% (13/17) and 89.6% (484/540). Sensitivity and specificity for RIF resistance detection of the Anyplex plus MDR-TB Detection kit were 100% (3/3) and 97.9% (47/48), respectively, while those for INH resistance detection were 83.3% (5/6) and 100% (45/45). CONCLUSION: The Anyplex plus MTB/NTM Detection kit showed good diagnostic performance for detection of MTB and NTM. Especially in MTB-positive cases, the Anyplex plus MDR-TB Detection kit provided rapid and reliable results of drug resistance to RIF and INH.
Drug Resistance ; Isoniazid ; Molecular Diagnostic Techniques ; Mycobacterium tuberculosis ; Nontuberculous Mycobacteria ; Nucleic Acid Amplification Techniques ; Real-Time Polymerase Chain Reaction ; Rifampin ; Tuberculosis, Multidrug-Resistant

OBJECTIVETo establish real-time PCR and loop-mediated isothermal amplification (LAMP) systems for detecting Cryptococcus neoformans CAP10 gene.

METHODSSpecific primers were designed targeting CAP10 gene of Cryptococcus neoformans, and the plasmid was constructed. After optimization of the reaction condition, the plasmid was quantitatively detected using real-time PCR and LAMP, and the detection sensitivity and specificity were evaluated. Clinical samples were also detected using the two methods.

RESULTSThe detection sensitivity of real-time PCR and LAMP was 6.8×10(1) and 6.8×10(3) copies, respectively. Real-time PCR yielded a higher positivity rate than LAMP. Both of the two methods showed a high detection specificity and produced negative results in the detection of Neisseria meningitidis, Candida albicans, Candida tropicalis, Aspergillus flavus, Aspergillus niger and Escherichia coli.

CONCLUSIONReal-time PCR is highly sensitive and specific for detecting Cryptococcus neoformans CAP10 gene but requires sophisticated equipment. LAMP, though with a relatively lower sensitivity, is simple to operate without the need of special equipment, and the result can be conveniently observed. Both of the two methods are suitable for detecting Cryptococcus neoformans and evaluating the treatment outcomes.

Cryptococcus neoformans ; genetics ; Fungal Proteins ; genetics ; Nucleic Acid Amplification Techniques ; methods ; Plasmids ; RNA, Fungal ; genetics ; RNA, Messenger ; genetics ; Real-Time Polymerase Chain Reaction ; methods ; Sensitivity and Specificity

This study aimed to develop a portable, accurate and easy-to-operate scheme for rapid detection of respiratory virus nucleic acid. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to verify the effect of extraction-free respiratory virus treatment reagent (RTU) on viral nucleic acid treatment and the effect of ultra-fast fluorescence quantitative PCR instrument (FQ-8A) on nucleic acid amplification, respectively. RTU and FQ-8A were combined to develop a rapid detection scheme for respiratory virus nucleic acid, and the positive detection rate was judged by C_t value using a fluorescence quantitative PCR instrument, and the accuracy of the scheme in clinical samples detection was investigated. The results showed that RTU had comparable sensitivity to the automatic nucleic acid extraction instrument, its extraction efficiency was comparable to the other 3 extraction methods when extracting samples of different virus types, but the extraction time of RTU was less than 5 min. FQ-8A had good consistency in detection respiratory syncytial virus (RSV) and adenovirus (ADV) compared with the control instrument ABI-7500, with kappa coefficients of 0.938 (P < 0.001) and 0.887 (P < 0.001), respectively, but the amplification time was only about 0.5 h. The RTU and FQ-8A combined rapid detection scheme had a highly consistent detection rate with the conventional detection scheme, with a sensitivity of 91.70% and specificity of 100%, and a kappa coefficient was 0.944 (P < 0.001). In conclusion, by combining RTU with FQ-8A, a rapid respiratory virus nucleic acid detection scheme was developed, the whole process could be completed in 35 min. The scheme is accurate and easy-to-operate, and can provide important support for the rapid diagnosis and treatment of respiratory virus.
Humans ; Respiratory Syncytial Virus Infections/diagnosis* ; Respiratory Syncytial Virus, Human/genetics* ; Nucleic Acid Amplification Techniques ; Real-Time Polymerase Chain Reaction ; Adenoviridae ; Sensitivity and Specificity

A reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed to rapidly detect foot-and-mouth disease virus serotype C (FMDV C). By testing 10-fold serial dilutions of FMDV C samples, sensitivity of the FMDV C RT-LAMP was found to be 10 times higher than that of conventional reverse transcription-PCR (RT-PCR). No cross-reactivity with A, Asia 1, or O FMDV or swine vesicular disease virus (SVDV) indicated that FMDV C RT-LAMP may be an exciting novel method for detecting FMDV C.
Animals ; Foot-and-Mouth Disease/*diagnosis ; Foot-and-Mouth Disease Virus/genetics ; Nucleic Acid Amplification Techniques/*methods/veterinary ; Reverse Transcriptase Polymerase Chain Reaction/veterinary ; Reverse Transcription/genetics ; Sensitivity and Specificity

A simple and sensitive Reverse Transcription Loop-mediated Isothermal Amplification (RT-LAMP) method was established to provide a new alternative for clinical diagnosis of Avian influenza A H5N1 virus. The method employed a set of six specially designed primers that recognized eight distinct sequences of the target for amplification of nucleic acid under isothermal conditions. In current study, fifty-one experimentally infected animal specimens and viral cultures that had been tested were analyzed by RT-LAMP for NA gene and HA gene, respectively. The amplification process of LAMP was monitored in real-time by the addition of SYBR Green dye. Meanwhile, the result showed high correlation between nested PCR and RT-LAMP. The specificity of the RT-LAMP assay was confirmed by restriction enzyme digestion analysis and sequencing of the amplified product. When the sensitivity of this assay was tested by serial 10-fold dilutions of RNA molecules from specimens, it was found that the RT-LAMP method achieved theoretically a sensitivity of 10 RNA molecules. Thus, we concluded that the RT-LAMP assay has potential usefulness for rapid detection of the Avian influenza A H5N1 virus.
Animals ; Birds ; Influenza A Virus, H5N1 Subtype ; genetics ; isolation & purification ; Influenza in Birds ; diagnosis ; virology ; Nucleic Acid Amplification Techniques ; methods ; Reproducibility of Results ; Reverse Transcriptase Polymerase Chain Reaction ; methods ; Sensitivity and Specificity

OBJECTIVETo develop a quantitative PCR method for detecting hookworm infection and quantification.

METHODSA real-time PCR method was designed based on the intergenic region II of ribosomal DNA of the hookworm Necator americanus. The detection limit of this method was compared with the microscopy-based Kato-Katz method. The real-time PCR method was used to conduct an epidemiological survey of hookworm infection in southern Fujian Province of China.

RESULTSThe real-time PCR method was specific for detecting Necator americanus infection, and was more sensitive than conventional PCR or microscopy-based method. A preliminary survey for hookworm infection in villages of Fujian Province confirmed the high prevalence of hookworm infections in the resident populations. In addition, the infection rate in women was significantly higher than that of in men.

CONCLUSIONSA real-time PCR method is designed, which has increased detection sensitivity for more accurate epidemiological studies of hookworm infections, especially when intensity of the infection needs to be considered.

Animals ; China ; epidemiology ; DNA, Helminth ; genetics ; Female ; Humans ; Male ; Microscopy ; Necator americanus ; genetics ; isolation & purification ; Necatoriasis ; diagnosis ; epidemiology ; genetics ; Nucleic Acid Amplification Techniques ; Real-Time Polymerase Chain Reaction ; Sensitivity and Specificity ; Sentinel Surveillance ; Sequence Analysis, DNA ; Sex Distribution

OBJECTIVETo develop a simple, rapid and sensitive colorimetric reverse-transcription loop-mediated isothermal amplification (RT-LAMP) for rapid detection of coxsackievirus A6 (CV-A6) based on the colour chang of hydroxy naphthol blue (HNB).

METHODSThe method employed a set of six primers that recognized sequences of VP1 gene for amplification of nucleic acid under isothermal conditions at 63 °C for 50 min. The products were detected through visual inspection of color change by the pre-addition of HNB dye. The specificity was validated by detecting a collection of different human enteroviruses. The sensitivity of this assay was evaluated by serial dilutions of RNA molecules from in vitro transcription of CV-A6 VP1 gene, and compared with real-time RT-PCR (rRT-PCR) in parallel. This assay was evaluated with 92 clinical specimens from patients with hand-foot-mouth disease.

RESULTSA positive color (sky blue) was only observed in the preparation of CV-A6, whereas none of the other 23 kinds of human enteroviruses showed a color change. The HNB based RT-LAMP showed a sensitivity of 100 copies/reaction, which was at the same level as that of the rRT-PCR. The result of RT-LAMP in analysis of 92 clinical specimens was consistent with that of the rRT-PCR. The kappa correlation between the two methods was 1 and both of the sensitivity and specificity of the RT-LAMP assay were 100%.

CONCLUSIONThe established RT-LAMP assay had good specificity and sensitivity and thus demonstrated to be a promising screening tool for CV-A6 infection. It also has the potential to be used in resource-limited clinical sites and field study.

Colorimetry ; Coloring Agents ; chemistry ; DNA Primers ; Enterovirus ; isolation & purification ; Hand, Foot and Mouth Disease ; virology ; Humans ; Indicators and Reagents ; chemistry ; Naphthalenesulfonates ; chemistry ; Nucleic Acid Amplification Techniques ; Real-Time Polymerase Chain Reaction ; Reverse Transcription ; Sensitivity and Specificity

OBJECTIVEUnbiased next generation sequencing (NGS) is susceptible to interference from host or environmental sequences. Consequently, background depletion and virome enrichment techniques are usually needed for clinical samples where viral load is much lower than background sequences.

METHODSA viral Sequence Independent Targeted Amplification (VSITA) approach using a set of non-ribosomal and virus-enriched octamers (V8) was developed and compared with traditionally used random hexamers (N6). Forty-five archived clinical samples of different types were used in parallel to compare the V8 and N6 enrichment performance of viral sequences and removal performance of ribosomal sequences in the step of reverse transcription followed by quantitative PCR (qPCR). Ten sera samples from patients with fever of unknown origin and 10 feces samples from patients with diarrhea of unknown origin were used in comparison of V8 and N6 enrichment performance following NGS analysis.

RESULTSA minimum 30 hexamers matching to viral reference sequences (sense and antisense) were selected from a dataset of random 4,096 (46) hexamers (N6). Two random nucleotides were added to the 5' end of the selected hexamers, and 480 (30 × 42) octamers (V8) were obtained. In general, VSITA approach showed higher enrichment of virus-targeted cDNA and enhanced ability to remove unwanted ribosomal sequences in the majorities of 45 predefined clinical samples. Moreover, VSITA combined with NGS enabled to detect not only more viruses but also achieve more viral reads hit and higher viral genome coverage in 20 clinical samples with diarrhea or fever of unknown origin.

CONCLUSIONThe VSITA approach designed in this study is demonstrated to possess higher sensitivity and broader genome coverage than traditionally used random hexamers in the NGS-based identification of viral pathogens directly from clinical samples.

Base Sequence ; Genome, Viral ; High-Throughput Nucleotide Sequencing ; Humans ; Nucleic Acid Amplification Techniques ; methods ; RNA, Viral ; genetics ; Real-Time Polymerase Chain Reaction ; Virus Diseases ; diagnosis ; virology ; Viruses ; isolation & purification