• Journal of Microbiology and Biotechnology
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• v.31 no.2
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• pp.226-232
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• 2021

Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging phlebovirus of the Phenuiviridae family that has been circulating in the following Asian countries: Vietnam, Myanmar, Taiwan, China, Japan, and South Korea. Despite the increasing infection rates and relatively high mortality rate, there is limited information available regarding SFTSV pathogenesis. In addition, there are currently no vaccines or effective antiviral treatments available. Previous reports have shown that SFTSV suppresses the host immune response and its nonstructural proteins (NSs) function as an antagonist of type I interferon (IFN), whose induction is an essential part of the host defense system against viral infections. Given that SFTSV NSs suppress the innate immune response by inhibiting type I IFN, we investigated the mechanism utilized by SFTSV NSs to evade IFNmediated response. Our co-immunoprecipitation data suggest the interactions between NSs and retinoic acid inducible gene-I (RIG-I) or TANK binding kinase 1 (TBK1). Furthermore, confocal analysis indicates the ability of NSs to sequester RIG-I and related downstream molecules in the cytoplasmic structures called inclusion bodies (IBs). NSs are also capable of inhibiting TBK1-interferon regulatory factor 3 (IRF3) interaction, and therefore prevent the phosphorylation and nuclear translocation of IRF3 for the induction of type I IFN. The ability of SFTSV NSs to interact with and sequester TBK1 and IRF3 in IBs demonstrate an effective yet unique method utilized by SFTSV to evade and suppress host immunity.

• Journal of Microbiology and Biotechnology
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• v.28 no.11
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• pp.1928-1936
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• 2018

Recently, human infections caused by severe fever with thrombocytopenia syndrome virus (SFTSV), which can lead to fatality, have dramatically increased in East Asia. With the unavailability of vaccines or antiviral drugs to prevent and/or treat SFTSV infection, early rapid diagnosis is critical for prevention and control of the disease. Here, we report the development of a simple, rapid and sensitive portable detection method for SFTSV infection applying reverse transcription-loop mediated isothermal amplification (RT-LAMP) combined with one-pot colorimetric visualization and electro-free reaction platform. This method utilizes a pocket warmer to facilitate diagnosis in a resource-limited setting. Specific primers were designed to target the highly-conserved region of L gene of SFTSV. The detection limit of the RT-LAMP assay was approximately $10^0$ viral genome copies from three different SFTSV strains. This assay exhibited comparable sensitivity to qRT-PCR and 10-fold more sensitivity than conventional RT-PCR, with a rapid detection time of 30 to 60 minutes. The RT-LAMP assay using SFTSV clinical specimens has demonstrated a similar detection rate to qRT-PCR and a higher detection rate compared to conventional RT-PCR. Moreover, there was no observed cross-reactive amplification of other human infectious viruses including Japanese Encephalitis Virus (JEV), Dengue, Enterovirus, Zika, Influenza and Middle East Respiratory Syndrome Coronavirus (MERS-CoV). This highly sensitive, electro- and equipment-free rapid colorimetric visualization method is feasible for resource-limited SFTSV field diagnosis.

• Korean Journal of Clinical Laboratory Science
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• v.52 no.4
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• pp.356-363
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• 2020

The distribution of ticks and severe fever with thrombocytopenia syndrome virus (SFTSV) pathogens were investigated by collecting ticks from March to November 2018 in four environments (grass fields, copses, mountain roads, and tombs) in Jeju. Three thousand and ninety ticks were collected using a tick trap, and 1,569 ticks were collected using the flagging method. Of the 4,659 ticks collected, Haemaphysalis longicornis and Haemaphysalis flava accounted for 4,440 ticks (95.2%) and 219 ticks (4.7%), respectively. Nine hundred and fifty, 883, 847, and 410 ticks were collected from grass fields, copses, mountain roads, and tombs, respectively, using tick traps, whereas 704, 472, 197, and 196 ticks were collected from copses, mountain roads, tombs, and grass fields, respectively, using the flagging method. The largest fraction of ticks (2,978) was collected from April to August, and most were collected in May and June. Adult ticks comprised 94 percent of the total ticks from June to August. SFTSV was not detected in the 4,440 H. longicornis ticks or the 219 H. flava ticks collected in this study.

• Korean Journal of Veterinary Service
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• v.39 no.2
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• pp.75-80
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• 2016

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging disease characterized by fever and thrombocytopenia. Haemaphysalis longicornis ticks comprise the major population of ticks in the environment and have been considered as the main vector for SFTS virus (SFTSV). Here we investigated the distribution of ticks carrying SFTSV collected from the environment using the dragging or sweeping methods during April~October 2015 in Jeollanam-do, Korea. Sampling was taken from Songjeong, Omi, Bangkwang, Sandong areas in Jiri walking trails. Among the total 3,869 ticks collected, 3,823 ticks (98.8%) were H. longicornis, 41 (1.1%) were Amblyomma testudinarium, and 5 (0.1%) were Ixodes nipponensis. Classification results by regional groups of H. longicornis indicated that 1,613 ticks were collected in Sandong, 1,190 ticks in Omi, 603 ticks in Bangkwang, and 417 ticks in Songjeong. In monthly distributional studies of H. longicornis based on the developmental stages, nymph (325 ticks) was collected from May to October, 94% of larvae from April to June, and 94% of adult from June to August. These results showed the different dominant stage of ticks according to seasons. However, no SFTSV-specific gene was detected in 3,823 ticks of H. longicornis, 41 of A. testudinarium and 5 of I. nipponensis.

• Parasites, Hosts and Diseases
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• v.60 no.1
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• pp.65-71
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• 2022

Severe fever with thrombocytopenia syndrome virus (SFTSV) is a zoonotic, tick-borne RNA virus of the genus Bandavirus (Family Phenuiviridae), mainly reported in China, Japan, and the Republic of Korea (Korea). For the purpose of this study, a total of 3,898 adult and nymphal ticks of species Haemaphysalis longicornis (94.2%), Haemaphysalis flava (5.0%), Ixodes nipponensis (0.8%), and 1 specimen of Ixodes ovatus, were collected from the Deogyusan National Park, Korea, between April 2016 and June 2018. A single-step reverse transcriptase-nested PCR was performed, targeting the S segment of the SFTSV RNA. Total infection rate (IR) of SFTSV in individual ticks was found to be 6.0%. Based on developmental stages, IR was 5.3% in adults and 6.0% in nymphs. The S segment sequences obtained from PCR were divided into 17 haplotypes. All haplotypes were phylogenetically clustered into clades B-2 and B-3, with 92.7% sequences in B-2 and 7.3% in B-3. These observations indicate that the Korean SFTSV strains were closer to the Japanese than the Chinese strains. Further epidemiological studies are necessary to better understand the characteristics of the Korean SFTSV and its transmission cycle in the ecosystem.

• Journal of the korean veterinary medical association
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• v.49 no.7
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• pp.424-429
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• 2013

• Journal of the korean veterinary medical association
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• v.49 no.6
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• pp.359-364
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• 2013

• Korean Journal of Veterinary Service
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• v.44 no.2
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• pp.93-102
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• 2021

In this study, a total of 9,449 hard ticks were collected once a month from April to October 2020 from a neighborhood park in Daejeon by flagging & dragging method and CO₂ manned trap method. The collected ticks were classified according to the Yamagutsi search table using a stereoscopic microscope and molecular biological analysis of four pathogens (SFTSV, Anaplasma spp., Ehrlichia spp., Borrellia spp.). As a result of the study, Haemaphysalis longicornis were collected the most in all areas of the five boroughs at a rate of 82 to 96 percent, while adults were collected the most in May to July, nymphs were collected the most in April to June, and larvae from August to October at a rate of 78 percent to 98 percent. In pathogens, three cases of SFTSV were detected, showing a minimum infection rate (MIR) of 0.46%, while Anaplasma spp. and Ehrlichia spp. were detected one each, with 0.15% and Borrelia spp. with a minimum infection rate of 0.46%. The detected SFTSV showed 99.9% homogeneity with the KF781490 detected in Cheongwon-gun, Chungbuk Province, Anaplasma spp. showed 99.0% homogeneity with JN990105 detected in China, and Erhlichia spp. showed 98.9% genetic similarity with U96436 separated from the U.S. In this study, the distribution status and pathogen infection rate of the hard ticks in the Daejeon area are analyzed and provided as basic data for the prevention of the hard tick-borne infectious disease.

• Korean Journal of Veterinary Service
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• v.43 no.4
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• pp.217-225
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• 2020

This study was conducted to survey pathogens of canine coronavirus (CCV), canine distemper virus (CDV), canine influenza virus (CIV), canine parvovirus (CPV), severe fever with thrombocytopenia syndrome virus (SFTSV), Dirofilaria (D.) immitis, Giardia and antibodies against Anaplasma (A.) phagocytophilum, Borrelia (B.) burgdorferi, Brucella (B.) canis and Ehrlichia (E.) canis among stray dogs in Gyeonggi province. We collected 271 feces, 291 bloods, 311 nasal and ocular swab samples from 311 of dogs in the Gyeonggi province assistance dogs sharing center from January to December, 2019. Among canine infectious disease pathogens, Giardia was highly detected in 46/271 (17.0%) samples. Subsequently, CCV 10.3% (28/271), D. immitis 8.2% (24/291), CPV 4.1% (11/271), CDV 1.0% (3/311), A. phagocytophilum (antibody) 0.3% (1/291), E. canis (antibody) 0.3% (1/291) were detected. Based on the results, this study is expected to provide a useful reference for disease control and management of stray dogs.

• Journal of Veterinary Science
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• v.23 no.6
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• pp.83.1-83.7
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• 2022

Severe fever with thrombocytopenia syndrome (SFTS) is a zoonotic disease, and its clinical information and prevalence are important. This study was conducted on 22 feline patients from the Republic of Korea (ROK), suspected to suffer from a tick-borne disease. Four cats were positive for SFTS, and genotypes B-1, B-3, D, and F were identified. Clinical symptoms, such as anorexia, jaundice, thrombocytopenia, leukopenia, and hyperbilirubinemia, were detected. This is the first report of SFTS virus genotypes B-1, D, and F from cats in the ROK. Moreover, our results suggest that jaundice may be an indicator of SFTS in cats.