• Korean Journal of Veterinary Pathology
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• v.6 no.1
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• pp.11-18
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• 2002

The purpose of this study was to investigate to potective effects against transmissible gastyoenteritis virus (TGEV) infection in piglets by administration of the TGEV antiserum orally at 5 hrs, 24hrs and 36hrs after birth. five piglets administered the antiserum were experimentally infected with TGEV at four-day-old. Control group were four piglets infected with TGEV only. Serum antibody titers against TGEV were examined by serum neutralization(SN) test, dectection for TGEV or TGEV antigen from feces and small intestines was tested by reverse transcrption-polymerase chain reaction (RT-PCR) and indirect immunoflurescence (IFA). The results obtained were as follows; 1. The piglets administered the TGEV antiserum showed higher antibody titers than those of control group and sustained during the experimental period. 2. The detection rate of TGEV in feces and small intestines by RT- PCR were 24.5% and 20.0% in TGEV antiserum treated group and 44.0% and 75.0% in control group, respectively. 3 The detection rate of TGEV antigen in the small intestine by IFA were 26.7% in TGEV antiserum treated group and 75.0% in control group, respectively. It was concluded that oral administration of antiserum against TGEV to piglets was effective in preventing TGEV infection.

• Proceedings of the Microbiological Society of Korea Conference
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• 2008.05a
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• pp.171-171
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• 2008

We monitored the occurrence of human enteric viruses in urban rivers by cell culture-PCR and RT-nested PCR. Water samples were collected monthly or semimonthly between May 2002 and March 2003 in four urban tributaries. Enteric viruses were detected by RT-nested PCR and cell culture-PCR based on a combination of Buffalo Green monkey kidney (BGMK) and A549 cell lines, followed by phylogenetic analysis of amplicons. By RT-nested PCR analysis, 45 (77.6%), 32 (55.2%), 32 (55.2%), 26 (44.8%), 12 (20.7%), 2 (3.4%), 4 (6.9%), and 4 (6.9%) of 58 samples showed positive results with adenoviruses, enteroviruses, noroviruses (NV) genogroup I (GI) and II (GII), reoviruses, hepatitis A viruses, rotaviruses and sapoviruses, respectively. Adenoviruses were most often detected and only eight (13.8%) samples were negative for adenoviruses and positive for other enteric viruses in the studied sites. Thirty-one (77.5%) of the 40 samples were positive for infectious adenoviruses and/or enteroviruses based on cell culture-PCR, and the frequency of positive samples grown on A549 and BGMK (65.0%) was higher than that grown on BGMK alone (47.5%). The occurrence of each enteric virus, except reoviruses and hepatitis A viruses was not statistically correlated with the water temperature and levels of fecal coliforms according to Binary logistic regression model. By sequence analysis, most strains of adenoviruses and enteroviruses detected in this study are similar to the causative agent of viral diseases in Korea and most NV GI- and GII-grouped strains were closely related to the reference strains from China and Japan, and GII/4-related strains had similar sequences to strains recognized as a worldwide epidemic outbreak. Our results suggested that monitoring human enteric viruses is necessary to improve microbial quality and cell culture-PCR using the combination of A549 and BGMK cells and the adenovirus detection by PCR could be useful for monitoring viral contamination in the aquatic environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.193-204
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• 2017

The security of Internet systems critically depends on the capability to keep anti-virus (AV) software up-to-date and maintain high detection accuracy against new malware. However, malware variants evolve so quickly they cannot be detected by conventional signature-based detection. In this paper, we proposed a malware classification method based on sequence patterns generated from the network flow of malware samples. We evaluated our method with 766 malware samples and obtained a classification accuracy of approximately 40.4%. In this study, malicious codes were classified only by network behavior of malicious codes, excluding codes and other characteristics. Therefore, this study is expected to be further developed in the future. Also, we can predict the attack groups and additional attacks can be prevented.

• Korean Journal of Veterinary Service
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• v.34 no.2
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• pp.139-148
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• 2011

Avian reovirus (ARV) and fowl adenovirus (FAdV) were evaluated for pathogenicity in specific pathogen free (SPF) chickens. ARV was isolated from the broilers with history of malabsorption syndrome (MAS). FAdV was isolated from the layer breeders with inclusion body hepatitis and hydropericardium syndrome. Total 6 inoculated groups including 1 un-inoculated group were organized and inoculated with the ARV and/or FAdV by oral route. The minimal pathological lesions and lower viral gene detection rates were present in the ARV inoculated groups compared to those of FAdV or ARV/FAdV inoculated groups. Common gross lesions in the ARV inoculated group were distended intestine with foamy contents and in the FAdV group there were foamy cecal contents and hydropericardium among the evaluation methods such as gross and histological lesion, viral gene detection, body weight and serum chemistry, histopathological lesion score was reliable especially in the liver lesions such as hepatic necrosis and lymphocytic infiltration. However, we did not success to evaluate the synergetic effect of mixed infection of ARV and FAdV in this study. Therefore, we need further study to reproduce malabsorption syndrome of ARV infection using different viral agent such as rotavirus and using different dose of virus.

• IMMUNE NETWORK
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• v.13 no.6
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• pp.264-274
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• 2013

The unrestricted population of $CD4^+Foxp3^+$ regulatory T (Treg) cells, which have been known to control the expression of autoimmune diseases and protective immunity to inflammatory reactions, has led to greater appreciation of functional plasticity. Detecting and/or isolating Ag-specific $CD4^+Foxp3^+$ Tregs at the single cell level are required to study their function and plasticity. In this study, we established and compared both MHC class II tetramer and intracellular CD154 staining, in order to detect $CD4^+Foxp3^+$ Treg specific for foreign Ag in acute and chronic infections with lymphocytic choriomeningitis virus (LCMV). Our results revealed that MHC class II tetramer staining showed a lower detection rate of LCMV $GP_{66-77}$-specific $CD4^+$ T cells because most of MHC class II tetramers were unbound and unstable when combined staining was performed with intracellular cytokines. In contrast, intracellular CD154 staining was revealed to be easier and simple for detecting LCMV $GP_{66-77}$-specific $CD4^+$ T cells, compared to MHC class II tetramer staining. Subsequently, we employed intracellular CD154 staining to detect LCMV $GP_{66-77}$-specific $CD4^+Foxp3^+$ Tregs using $Foxp3^{GFP}$ knock-in mouse, and found that LCMV $GP_{66-77}$-specific $CD4^+Foxp3^+$ Tregs and polyclonal $CD4^+Foxp3^+$ Tregs showed differential expansion in mice infected with LCMV Arms or Cl13 at acute (8 and 13 days pi) and chronic phases (35 days pi). Therefore, our results provide insight into the valuable use of intracellular CD154 staining to detect and characterize foreign Ag-specific $CD4^+Foxp3^+$ Treg in various models.

• Journal of Communications and Networks
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• v.16 no.4
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• pp.407-414
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• 2014

The Internet is a highly distributed and complex system consisting of billion devices and has become the field of various kinds of conflicts during the last two decades. As a matter of fact, various actors utilise the Internet for illicit purposes, such as for performing distributed denial of service attacks (DDoS) and for spreading various types of aggressive malware. Despite the fact that numerous services provide information regarding the threat level of the Internet, they are mostly based on information acquired by their sensors or on offline statistical sampling of various security applications (antivirus software, intrusion detection systems, etc.). This paper introduces proactive threat observatory system (PROTOS), an open-source early warning system that does not require a commercial license and is capable of estimating the threat level across the Internet. The proposed system utilises both a global and a local approach, and is thus able to determine whether a specific host is under an imminent threat, as well as to provide an estimation of the malicious activity across the Internet. Apart from these obvious advantages, PROTOS supports a large-scale installation and can be extended even further to improve the effectiveness by incorporating prediction and forecasting techniques.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.3
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• pp.519-529
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• 2019

Nowadays, intelligent Android malware applies anti-analysis techniques to hide malicious behaviors and make it difficult for anti-virus vendors to detect its presence. Malware can use background components to hide harmful operations, use activity-alias to get around with automation script, or wipe the logcat to avoid forensics. During our study, several static analysis tools can not extract these hidden components like main activity, and dynamic analysis tools also have problem with code coverage due to partial execution of android malware. In this paper, we design and implement a system to analyze intelligent malware that uses anti-analysis techniques to improve detection rate of evasive malware. It extracts the hidden components of malware, runs background components like service, and generates all the intent events defined in the app. We also implemented a real-time logging system that uses modified logcat to block deleting logs from malware. As a result, we improve detection rate from 70.9% to 89.6% comparing other container based dynamic analysis platform with proposed system.

• Convergence Security Journal
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• v.19 no.1
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• pp.11-17
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• 2019

Recently, the abuse of Internet technology has caused economic and mental harm to society as a whole. Especially, malicious code that is newly created or modified is used as a basic means of various application hacking and cyber security threats by bypassing the existing information protection system. However, research on small-capacity executable files that occupy a large portion of actual malicious code is rather limited. In this paper, we propose a model that can analyze the characteristics of known small capacity executable files by using data mining techniques and to use them for detecting unknown malicious codes. Data mining analysis techniques were performed in various ways such as Naive Bayesian, SVM, decision tree, random forest, artificial neural network, and the accuracy was compared according to the detection level of virustotal. As a result, more than 80% classification accuracy was verified for 34,646 analysis files.

• Fisheries and Aquatic Sciences
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• v.24 no.11
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• pp.351-359
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• 2021

The red sea bream iridovirus (RSIV) belonging to genus Megalocytivirus is responsible for red sea bream iridoviral disease (RSIVD) in marine and freshwater fishes. Although several diagnostic assays for RSIV have been developed, diagnostic sensitivity (DSe) and specificity (DSp) of real-time polymerase chain reaction (PCR) assays are not yet evaluated. In this study, we developed a TaqMan probe-based real-time PCR method and evaluated its DSe and DSp. To detect RSIV, the probe and primers were designed based on consensus sequences of the major capsid protein (MCP) genes from megalocytiviruses including RSIV, infectious spleen and kidney necrosis virus (ISKNV), and turbot reddish body iridovirus (TRBIV). The probe and primers were shown to be specific for RSIV, ISKNV, and TRBIV-types megalocytiviruses. A 95% limit of detection (LOD_95%) was determined to be 5.3 viral genome copies/µL of plasmid DNA containing the MCP gene from RSIV. The DSe and DSp of the developed real-time PCR assay for field samples (n = 112) were compared with those of conventional PCR assays and found to be 100% and 95.2%, respectively. The quantitative results for SYBR Green and TaqMan probe-based real-time PCR were not significantly different. The TaqMan probe-based real-time PCR assay for RSIV may be used as an appropriate diagnostic tool for qualitative and quantitative analysis.

• Korean Journal of Microbiology
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• v.41 no.4
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• pp.269-274
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• 2005

We evaluated the PCR assay and two commercialized PCR kits for the detection of mycoplasma in veterinary via live vaccines. The PCR assay could specifically detect all the tested Mycoplasma spp. and Acholeplasma spp., whereas two commercialized PCR kits did not. Also, the specificity of the PCR assay showed that 4 reference strains and 7 field isolates belonging to avian mycoplasma species could be all detected. The sensitivity of the PCR assay was determined using pure cultured Mycoplasma spp. and Acholeplasma spp. with a range of 1 to 100 colony forming units/ml in 9 CFR Mycoplasma broth. To test the availability of the PCR assay for veterinary live viral vaccines, A. laidlawii was artificially inoculated into the swine transmissible gastroenteritis-rota virus combined vaccine and canine parvovirus vaccine, respectively and the sensitivity of the PCR assay was similar with the result of cultured samples. In this study, the PCR assays could be used as rapid and sensitive methods for the detection of mycoplasma in veterinary live viral vaccines.