MassTag polymerase chain reaction for differential diagnosis of viral hemorrhagic fever.
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ABSTRACT:
SUBMITTER: Palacios G
PROVIDER: S-EPMC3294712 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Hemorrhagic fever with renal syndrome (HFRS) is confirmed by the isolation of hantavirus from serum, detection of virus-specific IgM, or a four-fold change in IgG titers during the acute and convalescent periods measured using an immunofluorescence assay (IFA). However, these tests are inefficient for early diagnosis. Therefore, this study investigated the usefulness of reverse-transcriptase nested polymerase chain reaction (RT-nPCR) for early diagnosis of HFRS using clinical samples such as urine and serum. Electronic medical records of eight patients with confirmed HFRS using IFA and RT-nPCR between May 2016 and May 2020 at Chosun University Hospital were reviewed. The virus was detected in all patients using RT-nPCR targeting the large (L) segment of hantavirus during the early phase in urine and serum. Importantly, the virus was identified in urine at a time when it was not identified in serum. Additionally, the virus was detected in urine and serum for up to 1 month after initial presentation with illness, but not in saliva, using RT-nPCR. We report eight HFRS cases diagnosed using urine and serum, but not using saliva, with RT-nPCR targeting the L-segment. Hantavirus RNA detection by RT-nPCR in urine and serum may aid the rapid diagnosis of HFRS during the early phase of the disease. In particular, HFRS should not be ruled out based on negative RT-PCR results in serum, and RT-PCR should be performed using urine as well as serum during the early phase of symptoms.
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Project description:Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne virus of the genus Nairovirus within the family Bunyaviridae. Infection can result in general myalgia, fever, and headache with some patients developing hemorrhagic fever with mortality rates ranging from 5% to 30%. CCHFV has a wide geographic range that includes Africa, Asia, the Middle East, and Europe with nucleotide sequence variation approaching 20% across the three negative-sense RNA genome segments. While phylogenetic clustering generally aligns with geographic origin of individual strains, distribution can be wide due to tick/CCHFV dispersion via migrating birds. This sequence diversity negatively impacts existing molecular diagnostic assays, leading to false negative diagnostic results. Here, we updated a previously developed CCHFV real-time reverse transcription polymerase chain reaction (RT-PCR) assay to include strains not detected using that original assay. Deep sequencing of eight different CCHFV strains, including three that were not detectable using the original assay, identified sequence variants within this assay target region. New primers and probe based on the sequencing results and newly deposited sequences in GenBank greatly improved assay sensitivity and inclusivity with the exception of the genetically diverse strain AP92. For example, we observed a four log improvement in IbAr10200 detection with a new limit of detection of 256 PFU/mL. Subsequent comparison of this assay to another commonly used CCHFV real-time RT-PCR assay targeting a different region of the viral genome showed improved detection, and both assays could be used to mitigate CCHFV diversity for diagnostics. Overall, this work demonstrated the importance of continued viral sequencing efforts for robust diagnostic assay development.
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Project description:Background and aimDifferent polymerase chain reaction (PCR) techniques have and are still being used for the direct detection of Brucella DNA in serum samples of different animal species and humans without being validated or properly validated, resulting in discrepancies. Thus, this study aimed to evaluate the diagnostic performance of the TaqMan Real-Time-PCR (RT-PCR) targeting the bcsp31 gene versus conventional PCR for the accurate diagnosis of brucellosis at the genus level in cattle sera.Materials and methodsOne hundred and eighty-four serum samples were collected from bacteriologically positive and negative cows with ages ranging from 1 to 5 years old at some infected private farms in the Nile Delta under quarantine measures as well as brucellosis free farms. These samples were classified into four groups after serological diagnosis and investigated by TaqMan RT-PCR and conventional PCR targeting the IS711 gene for Brucella DNA detection. The diagnostic performance characteristics of both PCR techniques were estimated considering the bacteriological results as a gold standard.ResultsTaqMan RT-PCR revealed superiority over conventional PCR; it was able to detect Brucella DNA in 95% (67/70) and 89% (25/28) of the cattle sera samples belonging to Group 1 (serologically and bacteriologically positive) and Group 2 (serologically negative but bacteriologically positive), respectively. On evaluating the diagnostic performance, TaqMan RT-PCR showed superior diagnostic sensitivity (93.9%), diagnostic specificity (88.4%), performance index (182.3), almost perfect kappa agreement (0.825±0.042), strong positive correlation (r=0.826), high accuracy based on the receiver operating characteristic (ROC) curve, and area under the ROC curve (0.911) at p<0.05 and CI of 95%.ConclusionA cattle serum sample is not the metric of choice for targeting Brucella genomic DNA by conventional PCR. The time-saving and rapid TaqMan RT-PCR method revealed a better diagnostic performance in the detection of Brucella DNA in cattle sera. Such performance offered by TaqMan RT-PCR may be considered a step toward the possibility of using such technology in the direct differentiation between Brucella-infected and -vaccinated cattle immunized by smooth vaccines from cattle sera using primers specific for such vaccines.
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Project description:Amoebiasis, a disease caused by Entamoeba histolytica, is usually diagnosed by microscopic examination, which does not differentiate the morphologically identical species of the E. histolytica/E. dispar complex. Furthermore, morphologically similar species such as Entamoeba hartmanni contribute to misidentification. Therefore, there is a need for more sensitive and specific methods. This study standardized a multiplex real-time PCR system for E. histolytica and E. dispar and a single real-time PCR for E. hartmanni. The multiplex protocol detected up to 0.0143 pg of E. histolytica DNA and 0.5156 pg of E. dispar DNA, and the average melting temperature (T(m)) was 73 °C and 70 °C, respectively. For E. hartmanni, the T(m) was 73 °C and the amplification was successful down to 0.03 fg of plasmid DNA. Negative controls and other intestinal parasites presented no amplification. Among the 48 samples tested, E. dispar DNA was detected in 37; none exhibited E. histolytica DNA and 11 were negative in the multiplex protocol. In 4 of these 11 samples, however, E. hartmanni DNA was amplified. SYBR Green is demonstrated to be an interesting option and these combined PCR reactions can improve laboratory diagnosis of amoebiasis in developing countries.
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Project description:Real-time polymerase chain reaction (real-time PCR) tests were successfully conducted in an aluminum-based microfluidic chip developed in this work. The reaction chamber was coated with silicone-modified epoxy resin to isolate the reaction system from metal surfaces, preventing the metal ions from interfering with the reaction process. The patterned aluminum substrate was bonded with a hydroxylated glass mask using silicone sealant at room temperature. The effect of thermal expansion was counteracted by the elasticity of cured silicone. With the heating process closely monitored, real-time PCR testing in reaction chambers proceeded smoothly, and the results show similar quantification cycle values to those of traditional test sets. Scanning electron microscope (SEM) and atomic force microscopy (AFM) images showed that the surface of the reaction chamber was smoothly coated, illustrating the promising coating and isolating properties. Energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma-optical emission spectrometer (ICP-OES) showed that no metal ions escaped from the metal to the chip surface. Fourier-transform infrared spectroscopy (FTIR) was used to check the surface chemical state before and after tests, and the unchanged infrared absorption peaks indicated the unreacted, antifouling surface. The limit of detection (LOD) of at least two copies can be obtained in this chip.
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Project description:Rhesus macaques (Macaca mulatta) infected with a lethal dose of lymphocytic choriomeningitis virus-strain WE (LCMV-WE) provide a model for Lassa fever virus infection of man. Like Lassa fever in human beings, disease begins with flu-like symptoms but can progress to morbidity fairly rapidly. Previously, we profiled the blood transcriptome of LCMV-infected monkeys (M. Djavani et al. J. Virol. 2007: PMID 17522210) showing distinct pre-viremic and viremic stages that discriminated between virulent and benign infections. In the present study, changes in liver gene expression from macaques infected with virulent LCMV-WE were compared to gene expression in uninfected monkeys as well as to monkeys that were infected but not diseased. We observed gene expression changes that occurred before the viremic stage of the disease, and could potentially serve as biomarkers that discriminate between exposure to a hemorrhagic fever virus and exposure to a benign virus. Based on a functional pathway analysis of differentially expressed genes, virulent LCMV-WE had a much broader effect on liver cell function than non-virulent virus. During the first few days of infection, virulent virus impacted gene expression associated with the generation of energy, such as fatty acid metabolism and glucose metabolism, with the complement and coagulation cascades, and with steroid metabolism, MAPK signaling and cell adhesion. For example, the energy profile resembled that of an organism entering starvation: acetyl-CoA carboxylase, a key enzyme of fatty acid synthesis, was shut down and gene products involved in gluconeogenesis were up-regulated. In conclusion, this study identifies several potential gene markers of LCMV-WE-associated liver disease and contributes to the database of gene expression changes correlated with LCMV pathogenesis in primates. 6 groups: uninfected controls, LCMV-WE infected (pre-viremic; day 1 to day 3), LCMV-WE infected (viremic; day 4 to day 7), LCMV-WE infected (post-viremic; day 8 to day 12), LCMV-Armstrong (LCMV-ARM; non-virulent strain) infected, and LCMV-ARM/LCMV-WE infected but not diseased. Each sample is from the liver of a different rhesus macaque.
2010-06-16 | E-GEOD-12254 | biostudies-arrayexpress
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Project description:Canine transmissible venereal tumor (CTVT) is the only naturally contagious tumor that is transmitted during coitus or social behaviors. Based on the tumor's location, the diagnosis of genital TVT (GTVT) is comparably easier than those in the extragenital area (ETVT) that are more easily incorrectly diagnosed. Fortunately, CTVT cells contain a specific long interspersed nuclear elements (LINE), inserted upstream of the myc gene, allowing a diagnostic polymerase chain reaction (PCR) based detection assay. The objectives of this study were aimed to improve the diagnostic accuracy by applying the diagnostic LINE1-c-myc PCR assay and fine needle aspiration (FNA) collection in direct comparison with standard cytological and histopathological analyses. Seventy-four dogs, comprised of 41 and 31 dogs with tumor masses at their external genitalia and extragenital areas (e.g. skin and nasal cavity), respectively, were included in this study. The signalment of these 65 dogs and clinical history of 20 client-owned dogs were collected. Samples were taken by biopsy for both histopathological examination and FNA for cytological examination and diagnostic PCR. The PCR products from 10 apparently CTVT samples were purified and sequenced. Sixty-one CTVT cases were diagnosed by cytological and histological analyses, but 65 were positive by the PCR assay. Overall, the PCR assay improved the accuracy of diagnostic CTVT results, especially for the more difficult ETVT tumors. Moreover, this PCR-based approach can facilitate the decision as to discontinue chemotherapy by discrimination between residual tumor cell masses and fibrotic tissue.
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