• The Plant Pathology Journal
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• v.38 no.4
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• pp.417-422
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• 2022

Apple stem grooving virus (ASGV) is a destructive viral pathogen of pome fruit trees that causes significant losses to fruit production worldwide. Obtaining ASGV-free propagation materials is essential to reduce economic losses, and accurate and sensitive detection methods to screen ASGV-free plantlets during in vitro propagation are urgently necessary. In this study, ASGV was sensitively and accurately quantified from in vitro propagated apple plantlets using a reverse transcription droplet digital polymerase chain reaction (RT-ddPCR) assay. The optimized RT-ddPCR assay was specific to other apple viruses, and was at least 10-times more sensitive than RT-real-time quantitative PCR assay. Furthermore, the optimized RT-ddPCR assay was validated for the detection and quantification of ASGV using micropropagated apple plantlet samples. This RT-ddPCR assay can be utilized for the accurate quantitative detection of ASGV infection in ASGV-free certification programs, and can thus contribute to the production of ASGV-free apple trees.

• Journal of Microbiology and Biotechnology
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• v.21 no.1
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• pp.100-108
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• 2011

A method for the rapid detection and quantification of Newcastle disease virus (NDV) produced in an animal cell culture-based production system was developed to enhance the speed of the NDV vaccine manufacturing process. A SYBR Green I-based real-time RT-PCR was designed with a conventional, inexpensive RT-PCR kit targeting the F gene of the NDV LaSota strain. The method developed in this study was validated for specificity, accuracy, precision, linearity, limit of detection (LOD), limit of quantification (LOQ), and robustness. The validation results satisfied the predetermined acceptance criteria. The validated method was used to quantify virus samples produced in an animal cell culture-based production system. The method was able to quantify the NDV samples from mid- or late-production phases, but not effective on samples from the early-production phase. For comparison with other quantifiable methods, immunoblotting, plaque assay, and tissue culture infectious dose 50 ($TCID_{50}$) assay were also performed with the NDV samples. The results demonstrated that the real-time RT-PCR method is suitable for the rapid quantification of virus particles produced in an animal cell-culture-based production system irrespective of viral infectivity.

• Horticultural Science & Technology
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• v.32 no.4
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• pp.544-549
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• 2014

Lily symptomless virus (LSV), Lily mottle virus (LMoV), and Cucumber mosaic virus (CMV) are the most prevalent viruses infecting lilies in Korea. Leaf and bulb samples showing characteristic symptoms of virus infection were collected in 2012, and 80 field samples were analyzed by reverse transcription polymerase chain reaction (RT-PCR). The infection frequencies were 79% for LMoV, 5% for LSV, and 3% for CMV. The LMoV coat protein gene was amplified and cloned into the pET21d(+) expression vector to develop serological diagnostic tools to detect LMoV. The resulting carboxy-terminal His-tagged coat proteins were expressed in Escherichia coli strain BL21 (DE3) by induction with IPTG. The recombinant proteins were purified using Ni-NTA agarose beads and used as an antigen to produce polyclonal antibodies in laying hens. The resulting egg yolk immunoglobulin (IgY) specifically recognized LMoV from infected plant tissues in immunoblotting assays and had comparable sensitivity to that of a mammalian antibody. In addition, method of immunocapture RT-PCR using this IgY was developed for sensitive, efficient, and rapid detection of LMoV. Based on these results, large-scale bulb tests and detection of LMoV in epidemiological studies can be performed routinely using this IgY. This is the first report of production of a polyclonal IgY against a plant virus and its use for diagnosis.

• Journal of Veterinary Science
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• v.21 no.2
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• pp.31.1-31.5
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• 2020

In this study, whiteleg shrimp (Penaeus vannamei) imported from Vietnam were collected from South Korean markets, and examined for 2 viruses: infectious hypodermal and hematopoietic necrosis virus (IHHNV, recently classified as decapod penstyldensovirus-1), and white spot syndrome virus (WSSV). Among 58 samples, we detected IHHNV in 23 samples and WSSV in 2 samples, using polymerase chain reaction and sequencing analyses. This is the first report of IHHNV and WSSV detection in imported shrimp, suggesting that greater awareness and stricter quarantine policies regarding viruses infecting shrimp imported to South Korea are required.

• Journal of Veterinary Science
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• v.23 no.2
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• pp.21.1-21.7
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• 2022

Newcastle disease (ND), infectious laryngotracheitis (ILT) and avian metapneumovirus (aMPV) can be similar making it critical to quickly differentiate them. Herein, we adapted pre-existing molecular-based diagnostic assays for NDV and ILTV, and developed new assays for aMPV A and B, for use under synchronized thermocycling conditions. All assays performed equivalently with linearity over a 5 log₁₀ dynamic range, a reproducible (R² > 0.99) limit of detection of ≥ 10 target copies, and amplification efficiencies between 86.8%-98.2%. Using biological specimens for NDV and ILTV showed 100% specificity. Identical amplification conditions will simplify procedures for detection in diagnostic laboratories.

• Korean Journal of Veterinary Service
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• v.22 no.3
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• pp.239-245
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• 1999

The reverse transcriptase polymerase chain reaction (RT-PCR) was used for the detection of bovine coronavirus (BCV) in fecal samples by using reverse transcriptase and two primers which flanked M gene sequence of 407bp. RT-PCR detected bovine coronavirus specifically, but did not detect mouse hepatitis virus (MHV), transmissible gastroenteritis virus (TGEV), and bovine rotavirus (BRV). The M gene sequences of MHV are homologus to that of BCV, but minor differences exist in the primer regions, preventing annealing of the primers. Detection of BCV using RT-PCR was compared with ELISA and the agreement of BCV detection by RT-PCR and ELISA was 95.3%. RNA detection in positive clinical specimens was significantly better by PCR than immunological detection of BCV by ELISA.

• The Plant Pathology Journal
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• v.31 no.3
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• pp.219-225
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• 2015

The primary step for efficient control of viral diseases is the development of simple, rapid, and sensitive virus detection. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) has been used to detect viral RNA molecules because of its simplicity and high sensitivity for a number of viruses. RT-LAMP for the detection of Potato virus X (PVX) was developed and compared with conventional reverse transcription polymerase chain reaction (RT-PCR) to demonstrate its advantages over RT-PCR. RT-LAMP reactions were conducted with or without a set of loop primers since one out of six primers showed PVX specificity. Based on real-time monitoring, RT-LAMP detected PVX around 30 min, compared to 120 min for RT-PCR. By adding a fluorescent reagent during the reaction, the extra step of visualization by gel electrophoresis was not necessary. RT-LAMP was conducted using simple inexpensive instruments and a regular incubator to evaluate whether RNA could be amplified at a constant temperature instead of using an expensive thermal cycler. This study shows the potential of RT-LAMP for the diagnosis of viral diseases and PVX epidemiology because of its simplicity and rapidness compared to RT-PCR.

• Journal of KIISE:Information Networking
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• v.34 no.3
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• pp.186-192
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• 2007

The virus throttling technique[5,6] is the one of well-known worm early technique. Virus throttling reduce the worm propagration by delaying connection packets artificially. However the worm detection time is not sufficiently fast as expected when the worm generated worm packets at a low rate. This is because the virus throttling technique use only delay queue length. In this paper we use the trend of weighted average delay queue length (TW AQL). By using TW AQL, the worm detection time is not only shorten at a low rate Internet worm, but also the false alarm does not largely increase. By experiment, we also proved our proposed algorithm had better performance.

• Journal of Plant Biotechnology
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• v.5 no.2
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• pp.83-86
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• 2003

A reverse transcription polymerase chain reaction (RT-PCR) protocol was developed using two specific 22-mer primers located in coat protein gene of SPFMV. A 411 bp PCR-product was detected in virus infected plants as well as tissue culture raised sweet potato but not in healthy plants. For optimization of RT-PCR protocol, the optimum crude nucleic acid concentration, annealing temperature, primer concentration and numbers of PCR-cycle for maximum sensitivity and specificity were determined. The optimum condition for RT-PCR was as follows: RT-PCR reaction mixture was one-step mixture, containing 50 pmol of primer, 30 units of reverse transcriptase, 5 units of RNasin, and the crude nucleic acid extracts (200 ng). In RT-PCR, cDNA was synthesized at $42^{\circ}C$ for 45 min before a quick incubation on ice after pre-denaturation at $95^{\circ}C$ for 5 min. The PCR reaction was carried out for 40 cycles at $96^{\circ}C$ for 30 see, $63^{\circ}C$ for 30 sec, $72^{\circ}C$ for 1 min, and finally at $72^{\circ}C$ for 10 min. The viral origin of the amplified product was confirmed by sequencing, with the sequence obtained having $95-98\%$ homology with published sequence data for SPFMV. The benefits of this RT-PCR based detection of SPFMV would be simple, rapid and specific.

• Journal of fish pathology
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• v.31 no.1
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• pp.49-55
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• 2018

Tendency of viral hemorrhagic septicemia virus (VHSV) detection from 2001 to 2016 in Korea was studied based on 15 reported cases. Since the VHSV was first detected from cultured olive flounder (Paralichthys olivaceus) in Pohang in 2001, it has been continuously reported from olive flounder farms in various regions of the Korean coastal area. So far, the virus has been detected from 2 farmed fishes, 12 wild marine fishes and 2 marine bivalves. All the 67 isolates were belong to VHSV genotype IVa. The predisposing factor analysis from different olive flounder farms revealed that the VHSV were highly detected from the juveniles under 40 g in body weight, in the temperature range from 9.5 to $17^{\circ}C$ and during the period of March to June. Therefore, we recommend that farmers, need to exercise caution against VHSV infection in Spring.