• 대한수의학회지
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• 제57권1호
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• pp.31-36
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• 2017

Japanese encephalitis (JE) is an important zoonosis caused by the mosquito-transmitted JE virus (JEV), which is a causative agent of reproductive failure in pregnant sows. Detection of JEV antibodies in swine is performed by hemagglutination inhibition (HI), virus neutralization (VN), and the plaque reduction neutralization test (PRNT). The most stringent PRNT is the 90% endpoint PRNT ($PRNT_{90}$). These conventional assays are difficult to carry out in diagnostic laboratories with insufficient instruments or cell culture systems. An alternative assay that is easily conducted and time efficient is required. In this study, we improved the indirect enzyme-linked immunosorbent assay (I-ELISA) with clarified antigen for the detection of JEV antibodies. The I-ELISA results obtained from 175 swine serum samples were compared with HI, VN, and $PRNT_{90}$ results. The sensitivity of I-ELISA was 91.8%, 95.0%, and 94.7% compared with HI, VN, and $PRNT_{90}$ results, respectively. The specificity of I-ELISA was 92.2%, 94.7%, and 94.7% compared with HI, VN, and $PRNT_{90}$ results, respectively. Moreover, the I-ELISA results were significantly correlated with the HI (r = 0.93), VN (r = 0.95), and $PRNT_{90}$ (r = 0.92) results. These results suggest that the improved I-ELISA is useful for serosurveillance of JEV in swine.

• 대한의생명과학회지
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• 제6권2호
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• pp.141-149
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• 2000

우리 나라에서 발생하고 있는 급성 출혈성 질환인 신증후출혈열의 원인 바이러스는 Family Bunyaviridae의 Genus Hantavirus에 속하는 한탄과 서울바이러스에 의하여 발생되고 있다. 본 연구에서는 신증후출혈열로 의뢰된 환자에서 한탄바이러스에 대한 항체가를 간접면역형광항체법(indirect immunofluorescent antibody technique, IFAT), 면역효소측정법 (enzyme-linked immunosorbent assay, ELISA) (IgG, IgM), 고비중입자응집반응 (high density composite particle agglutination, HDPA) 및 플라크감소중화시험 (plaque reduction neutralization test, PRNT) 등으로 비교 측정하였고, 신증후출혈열 환자로 확진된 15명의 한탄바이러스 혈청형을 PRNT와 혈청형 특이 역전사 효소 중합효소연쇄반응(nested reverse transcriptase polymerase chain reaction, nested RT-PCR)으로 확인하였다. 신증후출혈열로 의뢰된 환자에서의 한탄바이러스에 대한 IFAT, ELISA (IgG, IgM), HDPA그리고 PRNT비교에서 형광항체, ELISA IgG,응집항체 및 중화항체는 8명 모두 높게 나타났으며, ELISA IgM은 5명에서는 현저히 높은 항체를 보유하고 있었다. 신증후출혈 열 환자 15명에서는 높은 형광항체와 중화항체 역가를 나타내었고, 15명 중 12명은 한탄바이러스, 2명은 서울바이러스에 대한 높은 중화항체를 갖고 있었으며, 1명은 두 바이러스에 대하여 동일한 항체 역가를 나타내었으며, 혈청형 특이 primer를 사용한 nested RT-PCR에서는 15명 중 3명과 1명만이 한탄바이러스와 서울바이러스 primer에 대해 RNA가 검출되었다.

• 대한의생명과학회지
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• 제8권4호
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• pp.269-273
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• 2002

Dengue fever (DF) is an acute febrile illness caused by dengue viruses in the family Flaviviridae, genus Flavivirus. DF has so far posed any problem in Korea, however it has been recently believed to be associated with oversea's traveler infected with dengue virus. Antibody titers of sera from DF patients against dengue virus were measured by indirect immunofluorescence assay (IFA) and plaque reduction neutralization test (PRNT), including the haematologic test. Three of patients with DF showed highly fluorescent and neutralizing antibody titers by IFA and PRNT assay. Two of them showed higher, remarkably. Meanwhile, one of them was tested and resulted in severe tirombocytopenia, elevated serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) activities as well as mild leucopenia, increased monocytes and basophils and depressed lymphocytes in haematological differential count.

• 대한바이러스학회지
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• 제30권1호
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• pp.11-18
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• 2000

Since $Hantavax^{TM}$, formalin inactivated Hantaan virus vaccine (10,240 ELISA units/ml), has been developed in 1990 to prevent against haemorrhagic fever with renal syndrome (HFRS) caused by Hantaan or Seoul virus, it has been commercially available in Korea. Twenty-one healthy people were booster shot once and twice after primary basic vaccination with $Hantavax^{TM}$. Seroconversion rates were measured by immunofluorescent antibody technique (IFAT), enzyme-linked immunosorbent assay (ELISA), high density composite particle agglutination (HDPA), and plaque reduction neutralization test (PRNT). Seroconversion rates of 21 vaccinees at one year after primary basic vaccination were 52.3%, 95.2%, 0.0%, 47.6%, and 28.6%, and 13 vaccinees at one month after 1st booster vaccination were 100%, 100%, 30.7%, 100% and 100% by IFAT, ELISA (IgG, IgM), HDPA and PRNT, respectively. Seroconversion rates declined slightly by twenty months, and they were 84.6%, 92.3%, 0.0%, 84.6% and 69.2% by IFAT, ELISA (IgG, IgM), HDPA and PRNT, respectively. Seroconversion rates of 9 vaccinees at three months after 2nd booster vaccination were 100%, 100%, 0.0%, 100%, and 88.9%, and 16 vaccinees at one year after the 2nd booster vaccination were 87.5%, 93.8%, 0.0%, 87.5% and 81.3% by IFAT, ELISA (IgG, IgM), HDPA and PRNT, respectively. Based on the above result $Hantavax^{TM}$ has proved a vigorous anamnestic response after the 1st and the 2nd booster vaccination and has persisted higher fluorescence, agglutination and neutralizing antibody titers in vaccinees.

• IMMUNE NETWORK
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• 제21권6호
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• pp.39.1-39.18
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• 2021

The high virulent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus that emerged in China at the end of 2019 has generated novel coronavirus disease, coronavirus disease 2019 (COVID-19), causing a pandemic worldwide. Every country has made great efforts to struggle against SARS-CoV-2 infection, including massive vaccination, immunological patients' surveillance, and the utilization of convalescence plasma for COVID-19 therapy. These efforts are associated with the attempts to increase the titers of SARS-CoV-2 neutralizing Abs (nAbs) generated either after infection or vaccination that represent the body's immune status. As there is no standard therapy for COVID-19 yet, virus eradication will mainly depend on these nAbs contents in the body. Therefore, serological nAbs neutralization assays become a requirement for researchers and clinicians to measure nAbs titers. Different platforms have been developed to evaluate nAbs titers utilizing various epitopes sources, including neutralization assays based on the live virus, pseudovirus, and neutralization assays utilizing recombinant SARS-CoV-2 S glycoprotein receptor binding site, receptor-binding domain. As a standard neutralization assay, the plaque reduction neutralization test (PRNT) requires isolation and propagation of live pathogenic SARS-CoV-2 virus conducted in a BSL-3 containment. Hence, other surrogate neutralization assays relevant to the PRNT play important alternatives that offer better safety besides facilitating high throughput analyses. This review discusses the current neutralization assay platforms used to evaluate nAbs, their techniques, advantages, and limitations.

• Pediatric Infection and Vaccine
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• 제4권1호
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• pp.116-125
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• 1997

목 적 : 국내에서 사용되고 일본뇌염 바이러스 백신에 대한 야외 실험을 실시하여 국내 백신 제조에 사용되는 Nakayama-NIH주의 국내 접종자에 대한 항체 생성율 및 중화 항체의 지속율을 조사하고, 일본뇌염 접종 스케줄의 재조정 및 국내 면역 집단의 민감도 조사 등을 통하여 방역 대책의 기초 자료로 활용하고자 하였다. 방 법 : 일본뇌염 백신의 면역효과 및 항체지속 기간을 알아보고자 1994년부터 계속 사업으로 강화군에 소재하고 있는 K 초등학교 학생들을 대상으로 조사를 실시하였다. 대상자들의 혈액을 시기에 따라 채혈하여 hemagglutination inhibition test (HI) 및 plaque reduction neutralization test (PRNT)를 실시하여 항체가를 조사하였다. 결 과 : 총 조사 대상자 213명은 이미 기초 접종이 끝난 자들로서 HI 항체가는 '95년 4월 백신 면역전에 이미 63.4%가 1:10 이상의 항체가를 가지고 있었으며 중화항체가는 전원이 1:20 이상의 항체가를 가지고 있었다. '95년 백신 접종 후 12개월이 지난 1996년 4월까지 HI 항체가 1:20 이상이 55.7%이며, 중화항체가는 전원이 1:20 이상을 보유하고 있었다. 이들에게 1996년 4월에 재접종 후 6개월째에는 HI 항체가가 1:10 이상이 69.7%로 증가하였고 G.M.T값은 1:11.6에서 1:13.23, 중화 항체의 G.M.T는 1:275.7에서 1:348.1로 증가하였다. 결 론 :위의 실험 결과에 따르면 현재 국내에서 사용중인 불활화 일본뇌염 백신은 자연계 에서 일본뇌염 바이러스가 공격하는 $10^5$ $LD_{50}$를 막을 수 있는 중화항체가 1:20을 기본면역 1회로 1년 이상 유지하고 있었으며, 충분한 boosting 효과를 보이고 있었다. 따라서 일본뇌염 백신의 추가면역은 기본접종후 개인의 상태에 따라 2~3년 간격의 추가접종이 적절하다 고 생각된다.

• Journal of Microbiology and Biotechnology
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• 제29권4호
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• pp.651-657
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• 2019

Although smallpox was eradicated in 1980, it is still considered a potential agent of biowarfare and bioterrorism. Smallpox has the potential for high mortality rates along with a major public health impact, eventually causing public panic and social disruption. Passive administration of neutralizing monoclonal antibodies (mAbs) is an effective intervention for various adverse reactions caused by vaccination and the unpredictable nature of emerging and bioterrorist-related infections. Currently, vaccinia immune globulin (VIG) is manufactured from vaccinia vaccine-boosted plasma; however, this production method is not ideal because of its limited availability, low specific activity, and risk of contamination with blood-borne infectious agents. To overcome the limitations of VIG production from human plasma, we isolated two human single-chain variable fragments (scFvs), (SC34 and SC212), bound to vaccinia virus (VACV), from a scFv phage library constructed from the B cells of VACV vaccine-boosted volunteers. The scFvs were converted to human IgG1 (VC34 and VC212). These two anti-VACV mAbs were produced in Chinese Hamster Ovary (CHO) DG44 cells. The binding affinities of VC34 and VC212 were estimated by competition ELISA to $IC_{50}$ values of $2{\mu}g/ml$ (13.33 nM) and $22{\mu}g/ml$ (146.67 nM), respectively. Only the VC212 mAb was proven to neutralize the VACV, as evidenced by the plaque reduction neutralization test (PRNT) result with a $PRNT_{50}$ of ~0.16 mg/ml (${\sim}1.07{\mu}M$). This VC212 could serve as a valuable starting material for further development of VACV-neutralizing human immunoglobulin for a prophylactic measure against post-vaccination complications and for post-exposure treatment against smallpox.

• Parasites, Hosts and Diseases
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• 제56권1호
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• pp.61-70
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• 2018

We developed a Rapid Diagnostic Test (RDT) kit for detecting IgG/IgM antibodies against Zika virus (ZIKV) using monoclonal antibodies to the envelope (E) and non-structural protein 1 (NS1) of ZIKV. These proteins were produced using baculovirus expression vector with Sf9 cells. Monoclonal antibodies J2G7 to NS1 and J5E1 to E protein were selected and conjugated with colloidal gold to produce the Zika IgG/IgM RDT kit (Zika RDT). Comparisons with ELISA, plaque reduction neutralization test (PRNT), and PCR were done to investigate the analytical sensitivity of Zika RDT, which resulted in 100% identical results. Sensitivity and specificity of Zika RDT in a field test was determined using positive and negative samples from Brazil and Korea. The diagnostic accuracy of Zika RDT was fairly high; sensitivity and specificity for IgG was 99.0 and 99.3%, respectively, while for IgM it was 96.7 and 98.7%, respectively. Cross reaction with dengue virus was evaluated using anti-Dengue Mixed Titer Performance Panel (PVD201), in which the Zika RDT showed cross-reactions with DENV in 16.7% and 5.6% in IgG and IgM, respectively. Cross reactions were not observed with West Nile, yellow fever, and hepatitis C virus infected sera. Zika RDT kit is very simple to use, rapid to assay, and very sensitive, and highly specific. Therefore, it would serve as a choice of method for point-of-care diagnosis and large scale surveys of ZIKV infection under clinical or field conditions worldwide in endemic areas.

• Pediatric Infection and Vaccine
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• 제8권2호
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• pp.150-159
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• 2001

목 적 : 현재 사용하고 있는 마우스 뇌조직 유래 Nakayama주 사백신 접종 방법의 의학적 타당성을 알아보고자 접종 실태와 부작용 발생 양상과 빈도를 조사하고 추가 접종 방법의 타당성을 확인하기 위하여 중화항체 지속률을 조사하였다. 방 법 : 15,487명의 접종아를 대상으로 이상반응 발생 여부를 조사하였고 초등학교 학생 2,277명을 대상으로 건강기록부와 설문지조사를 통하여 접종실태와 이상반응 발생 빈도를 확인하였으며 접종기록이 일치하는 311명의 학생을 대상으로 중화항체 검사를 시행하였다. 검사는 United States Armed Forces Research Institute of Medical Science/Department of Virology, Bangkok(USAMC-AFRIMS)에서 시행되었고 50% 플라크 감소를 기준으로 1 : 10 이상을 양성으로 하였다. 결 과 : 건강기록부에 의한 초등학생 2,277명의 접종률은 47.5%였으나 설문지 조사에서는 접종률이 93.5%로 큰 차이가 있었다. 건강기록부에 나타난 취학 전 접종률은 남자 48.5%, 여자 46.4%로 차이가 없었다. 연령이 증가함에 따라 일본뇌염의 접종 횟수도 증가하는 양상을 보였다. 예방접종 여부가 건강기록부와 설문지 조사 결과가 일치하는 경우는 95년과 96년에 모두 접종 받았다고 응답한 경우만 75.6%로 높았고 그 외에는 일치도가 낮았다. 일본뇌염 예방접종 장소는 학교가 60.1%로 가장 많았고 그 외 보건소가 25.1%, 병 의원 14.1% 순이었다. 1995년 5~6월 사이 서울 소재 보건소에서 15,487명을 대상으로 일본뇌염 사백신을 접종한 후 0.13%에서 이상반응이 발생하여 의료 기관을 방문하였으며 이 중 57%는 고열 때문이었고 1례에서 접종 후 3분만에 실신 발작이 있었다. 전체 접종자의 0.02%에서 심한 두드러기 반응으로 의료기관을 방문하였으며 0.03%에서 두통 및 구토 등으로 의료 기관을 다시 찾았다. 1996년 봄에 초등학생을 대상으로 시행한 이상반응 설문지 조사에 의하면 주사 부위 발적이 17.4%, 주사 부위 동통이 14.8%, 발열 4.3%였고 그 외에 두통, 구토, 반점 등이 관찰되었다. 초등학생 311명 중 일본뇌염 접종력 조사에서 마지막 접종 후 6개월이 경과한 경우(1군)가 155명, 접종 후 18개월이 경과한 경우(2군) 104명, 30개월이 경과한 경우(3군)이 45명, 42개월이 경과한 경우(4군)가 7명이었다. 이들의 항체 양성률은 1군이 98.1%(152/155), 2군이 99.0%(103/104), 3군이 95.6%(43/45), 4군이 71.4%(5/7)로 양성률에 있어서 각 군간의 차이는 없는 것으로 나타났다. 결 론 : 현재 격년으로 시행하고있는 일본뇌염 사백신 추가 접종은 시기를 늘려 시행하여도 항체 지속률을 유지할 수 있을 것으로 추정된다.

• Journal of Microbiology and Biotechnology
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• 제14권4호
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• pp.745-750
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• 2004

The objective of this collaborative study was to establish a Korean standard of Japanese encephalitis (JE) vaccine (mouse brain-derived, formalin-inactivated) for potency assay. A candidate preparation proposed as a Korean standard was provided by GreenCross Vaccine, and six laboratories, including one national control laboratory and five manufacturers of JE vaccine, participated in the study. The potency of the candidate preparation and a reference standard obtained from Japan was estimated by mouse immunogenicity assay using the in vitro plaque reduction neutralization test (PRNT). The results of 72 assays conducted by the 6 laboratories showed that the overall mean potency estimate of the candidate preparation was 2.455 log median plaque reduction neutralization antibody titer per 0.5-ml dosage administered twice in mice at 7-day intervals, and that the mean potency ratio of the candidate preparation relative to the reference standard was 1.074. The potency estimates were quite variable among laboratories irrespective of the preparation. The variability of assays assessed by Z scores and coefficient of variation (CV) were in general within the level of acceptance (Z scores within $\pm3$ and $CV\;\leq\;15%$). Therefore, we concluded that the candidate preparation would be suitable as a national standard for testing the potency of JE vaccine (inactivated).