Clinical validation of an automated reverse transcription-insulated isothermal PCR assay for the detection of severe acute respiratory syndrome coronavirus 2.
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ABSTRACT:
SUBMITTER: Chang PL
PROVIDER: S-EPMC7849545 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Middle East respiratory syndrome (MERS) is an emerging zoonotic viral respiratory disease that was first identified in Saudi Arabia in 2012. In 2015, the largest MERS outbreak outside of the Middle East region occurred in the Republic of Korea. The rapid nosocomial transmission of MERS-coronavirus (MERS-CoV) in Korean health care settings highlighted the importance and urgent need for a rapid and reliable on-site diagnostic assay to implement effective control and preventive measures. Here, the evaluation and validation of two newly developed reverse transcription-insulated isothermal PCR (RT-iiPCR) methods targeting the ORF1a and upE genes of MERS-CoV are described. Compared with World Health Organization-recommended singleplex real-time quantitative RT-PCR (RT-qPCR) assays, both RT-iiPCR assays had comparable analytical sensitivity for the detection of MERS-CoV RNA in tissue culture fluid and in sputum samples spiked with infectious virus. Furthermore, clinical evaluation was performed with sputum samples collected from subjects with acute and chronic respiratory illnesses, including patients infected with MERS-CoV. The overall agreement values between the two RT-iiPCR assays and the reference RT-qPCR assays were 98.06% (95% CI, 94.43%-100%; ? = 0.96) and 99.03% (95% CI, 95.88%-100%; ? = 0.99) for ORF1a and upE assays, respectively. The ORF1a and upE MERS-CoV RT-iiPCR assays coupled with a field-deployable system provide a platform for a highly sensitive and specific on-site tool for diagnosis of MERS-CoV infections.
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Project description:Recent outbreaks of severe acute respiratory syndrome (SARS) have spurred intense research efforts around the world to deal with the serious threat to health posed by this novel coronavirus. A rapid, reliable diagnostic assay is needed for monitoring the spread of the disease. Here we report a method for eliminating false-negative results and increasing test sensitivity, based on the hypothesis that the message encoded by the nucleocapsid (N) gene is the most abundant during viral infection. Nasopharyngeal aspirates and stool samples were obtained from suspected SARS patients with major clinical symptoms and a significant history of close contact with infected patients. Total RNAs were extracted in a 96-well format, together with pig kidney epithelial (PK-15) cells as an internal control for extraction efficiency. PCR inhibitors were removed by ethanol precipitation, and a PCR for the pig beta-actin gene was used as a positive control for all clinical samples. Samples were analyzed by a reverse transcriptase PCR assay. Northern blot analysis was performed to demonstrate differences in subgenomic transcripts of the virus, and a real-time quantitative PCR was employed to compare the sensitivities of two loci (1b and N). The detection rate of the assay reached 44.4% on day 9 after the onset of the disease. The diagnostic PCR amplifying the N gene gave an average of a 26.0% (6.3 to 60.0%) stronger intensity signal than that for the 1b gene. In conclusion, the nucleocapsid gene represents an additional sensitive molecular marker for the diagnosis of the SARS coronavirus and can be further adapted for use in a high-throughput platform assay.
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Project description:We developed a rapid insulated isothermal PCR (iiPCR) assay for on-site detection of Mannheimia haemolytica using a primer and probe set targeting the superoxide dismutase (sodA) gene. Our iiPCR assay detected M. haemolytica clinical isolates successfully and produced negative results on other bovine or ovine respiratory pathogens, including Histophilus somni, Bibersteinia trehalosi, Trueperella pyogenes, Streptococcus suis, and Mycoplasma spp., indicating that the PCR reactions were specific. Additionally, our iiPCR assay detected as few as 21 copies of genomic DNA and 17.2 cfu/mL of bacterial culture, which was 10 and 100 times more sensitive than conventional PCR, respectively. Our iiPCR assay can be performed on a portable device in a total of 58 min and may be a useful tool for the detection of M. haemolytica in bovine and ovine respiratory disease in the field.
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Project description:Bovine torovirus (BToV) is an important diarrhea-causing pathogen affecting bovines. To facilitate BToV detection, a reverse transcription insulated isothermal PCR (RT-iiPCR) assay was developed that targets the BToV M gene with high specificity and reproducibility. The assay has a limit of detection of 23 copies/μL. Out of 69 diarrheic fecal samples from yaks collected on six farms in Tibet and Sichuan provinces in China, 11.59% (8/69) tested positive for BToV using this assay. The full-length spike (S) and hemagglutinin-esterase (HE) genes of three positive samples were subsequently sequenced. Notably, an identical recombination event was identified in the S1 subunit of the S protein of three isolates. All of the HE genes were found to belong to genotype III and shared the same unique aa variation (P44S) in the esterase domain. This study is the first confirmation of BToV in yaks and the first report of an S gene recombination event in BToV. Our findings will enhance the current understanding of the molecular characteristics and genetic evolution of BToV.
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Project description:Foot-and-mouth disease (FMD) is a highly contagious viral disease of cloven-hoofed animals, which can decimate the livestock industry and economy of countries previously free of this disease. Rapid detection of foot-and-mouth disease virus (FMDV) is critical to containing an FMD outbreak. Availability of a rapid, highly sensitive and specific, yet simple and field-deployable assay would support local decision-making during an FMDV outbreak. Here we report validation of a novel reverse transcription-insulated isothermal PCR (RT-iiPCR) assay that can be performed on a commercially available, compact and portable POCKIT™ analyser that automatically analyses data and displays '+' or '-' results. The FMDV RT-iiPCR assay targets the 3D region of the FMDV genome and was capable of detecting 9 copies of in vitro-transcribed RNA standard with 95% confidence. It accurately identified 63 FMDV strains belonging to all seven serotypes and showed no cross-reactivity with viruses causing similar clinical diseases in cloven-hoofed animals. The assay was able to identify FMDV RNA in multiple sample types including oral, nasal and lesion swabs, epithelial tissue suspensions, vesicular and oral fluid samples, even before the appearance of clinical signs. Clinical sensitivity of the assay was comparable or slightly higher than the laboratory-based real-time RT-PCR assay in use. The assay was able to detect FMDV RNA in vesicular fluid samples without nucleic acid extraction. For RNA extraction from more complex sample types, a commercially available taco™ mini transportable magnetic bead-based, automated extraction system was used. This assay provides a potentially useful field-deployable diagnostic tool for rapid detection of FMDV in an outbreak in FMD-free countries or for routine diagnostics in endemic countries with less structured laboratory systems.
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Project description:Classical swine fever (CSF) is an OIE-listed disease that can have a severe impact on the swine industry. User-friendly, sensitive, rapid diagnostic tests that utilize low-cost field-deployable instruments for CSF diagnosis can be useful for disease surveillance and outbreak monitoring. In this study, we describe validation of a new probe-based insulated isothermal reverse transcriptase PCR (iiRT-PCR) assay for rapid detection of classical swine fever virus (CSFV) on a compact, user-friendly device (POCKIT(™) Nucleic Acid Analyzer) that does not need data interpretation by the user. The assay accurately detected CSFV RNA from a diverse panel of 33 CSFV strains representing all three genotypes plus an additional in vitro-transcribed RNA from cloned sequences representing a vaccine strain. No cross-reactivity was observed with a panel of 18 viruses associated with livestock including eight other pestivirus strains (bovine viral diarrhoea virus type 1 and type 2, border disease virus, HoBi atypical pestivirus), African swine fever virus, swine vesicular disease virus, swine influenza virus, porcine respiratory and reproductive syndrome virus, porcine circovirus 1, porcine circovirus 2, porcine respiratory coronavirus, vesicular exanthema of swine virus, bovine herpes virus type 1 and vesicular stomatitis virus. The iiRT-PCR assay accurately detected CSFV as early as 2 days post-inoculation in RNA extracted from serum samples of experimentally infected pigs, before appearance of clinical signs. The limit of detection (LOD95% ) calculated by probit regression analysis was 23 copies per reaction. The assay has a sample to answer turnaround time of less than an hour using extracted RNA or diluted or low volume of neat serum. The user-friendly, compact device that automatically analyses and displays results could potentially be a useful tool for surveillance and monitoring of CSF in a disease outbreak.
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Project description:A new human coronavirus (CoV), subsequently named Middle East respiratory syndrome (MERS)-CoV, was first reported in Saudi Arabia in September 2012. In response, we developed two real-time reverse transcription-PCR (rRT-PCR) assays targeting the MERS-CoV nucleocapsid (N) gene and evaluated these assays as a panel with a previously published assay targeting the region upstream of the MERS-CoV envelope gene (upE) for the detection and confirmation of MERS-CoV infection. All assays detected ≤10 copies/reaction of quantified RNA transcripts, with a linear dynamic range of 8 log units and 1.3 × 10(-3) 50% tissue culture infective doses (TCID50)/ml of cultured MERS-CoV per reaction. All assays performed comparably with respiratory, serum, and stool specimens spiked with cultured virus. No false-positive amplifications were obtained with other human coronaviruses or common respiratory viral pathogens or with 336 diverse clinical specimens from non-MERS-CoV cases; specimens from two confirmed MERS-CoV cases were positive with all assay signatures. In June 2012, the U.S. Food and Drug Administration authorized emergency use of the rRT-PCR assay panel as an in vitro diagnostic test for MERS-CoV. A kit consisting of the three assay signatures and a positive control was assembled and distributed to public health laboratories in the United States and internationally to support MERS-CoV surveillance and public health responses.
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Project description:In January 2021, the Chilean city of Concepción experienced a second wave of coronavirus 2019 (COVID-19) while in early April 2021, the entire country faced the same situation. This outbreak generated the need to modify and validate a method for detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in saliva, thereby expanding the capacity and versatility of testing for COVID-19. This study was conducted in February 2021 in the Chilean city of Concepción during which time, the town was under total quarantine. The study participants were mostly symptomatic (87.4%), not hospitalized, and attended care centers because of their health status rather than being asked by the researchers. People coming to the health center in Concepción to be tested for COVID-19 (via reverse transcriptase polymerase chain reaction [RT-PCR]) from a specimen of nasopharyngeal swab (NPS) were then invited to participate in this study. A total of 131 participants agreed to sign an informed consent and to provide saliva and NPS specimens to validate a method in terms of sensitivity, specificity, and statistical analysis of the cycle threshold (Ct) values from the RT-PCR. Calculations pertaining to the 127 participants who were ultimately included in the analysis showed sensitivity and specificity at 94.34% (95% CI: 84.34-98.82%) and 98.65% (95% CI: 92.70-99.97%), respectively. The saliva specimen showed a performance comparable to NPS as demonstrated by the diagnostic parameters. This RT-PCR method from the saliva specimen is a highly sensitive and specific alternative compared to the reference methodology, which uses the NPS specimen. This modified and validated method is intended for use in the in vitro diagnosis of SARS-CoV-2, which provides health authorities in Chile and local laboratories with a real testing alternative to RT-PCR from NPS.
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Project description:Novel Corona virus/Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2 or 2019-nCoV), and the subsequent disease caused by the virus (coronavirus disease 2019 or COVID-19), is an emerging global health concern that requires a rapid diagnostic test. Quantitative reverse transcription PCR (qRT-PCR) is currently the standard for SARS-CoV-2 detection; however, Reverse Transcription Loop-Mediated Isothermal Amplification (RT-LAMP) may allow for faster and cheaper field based testing at point-of-risk. The objective of this study was to develop a rapid screening diagnostic test that could be completed in 30-45 minutes. Simulated patient samples were generated by spiking serum, urine, saliva, oropharyngeal swabs, and nasopharyngeal swabs with a portion of the SARS-CoV-2 nucleic sequence. RNA isolated from nasopharyngeal swabs collected from actual COVID-19 patients was also tested. The samples were tested using RT-LAMP as well as by conventional qRT-PCR. Specificity of the RT-LAMP was evaluated by also testing against other related coronaviruses. RT-LAMP specifically detected SARS-CoV-2 in both simulated patient samples and clinical specimens. This test was performed in 30-45 minutes. This approach could be used for monitoring of exposed individuals or potentially aid with screening efforts in the field and potential ports of entry.
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Project description: Not available
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