• Pediatric Infection and Vaccine
• /
• v.29 no.3
• /
• pp.131-140
• /
• 2022

Purpose: Since the coronavirus disease 2019 (COVID-19) pandemic began, new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have emerged, and distinct epidemic waves of COVID-19 have occurred for an extended period. This study aimed to analyze the clinical and epidemiological characteristics of children with COVID-19 from the third wave to the middle of the fourth epidemic wave in Korea. Methods: We retrospectively reviewed the medical records of hospitalized patients aged ≤18 years with laboratory-confirmed COVID-19. The study periods were divided into the third wave (from November 13, 2020 to July 6, 2021) and the fourth wave (from July 7 to October 31, 2021). Results: Ninety-three patients were included in the analysis (33 in the third and 60 in the fourth waves). Compared with the third wave, the median age of patients was significantly older during the fourth wave (6.7 vs. 2.8 years, P=0.014). Household contacts was reported in 60.2% of total patients, similar in both periods (69.7 vs. 55.0%, P=0.190). Eighty-one (87.1%) had symptomatic SARS-CoV-2 infection. Among these, 10 (12.3%) had no respiratory symptoms. Anosmia or ageusia were more commonly observed in the fourth epidemic wave (10.7 vs. 34.0%, P=0.032). Most respiratory illness were upper respiratory tract infections (94.4%, 67/71), 4 had pneumonia. The median cycle threshold values (detection threshold, 40) for RNA-dependent RNA polymerase (RdRp) and envelope (E) genes of SARS-CoV-2 were 21.3 and 19.3, respectively. There was no significant difference in viral load during 2 epidemic waves. Conclusions: There were different characteristics during the two epidemic waves of COVID-19.

• The Journal of the Korean Society for Microbiology
• /
• v.14 no.1
• /
• pp.79-87
• /
• 1979

The immunosuppressive activity of newcastle disease virus(NDV) and some possible role of interferon(C-IF) in viral suppression of immune response were evaluated by SRBC-induced delayed-type hypersensitivity(DTH), rosette formation in spleen cells, number of lymphocytes in peripheral blood, hemagglutinin and hemolysin response to SRBC in ICR mice sensitized with SRBC. When NDV was inoculated before or after sensitization of mouse with SRBC, virus caused a marked inhibition of DTH, and its depressive effect was dependent on the time of virus inoculation in relation to SRBC sensitization or challenge. Rosette formation of spleen cells was significantly reduced by NDV infection. The degree of the depression of rosette formation was more prominent in mice inoculated before sensitization than after sensitization and could be related to the amount of serum interferon induced by the virus. Humoral response to SRBC of virus infected mouse was significantly depressed when NDV was inoculated 24 or 48 hours before sensitization. However, there was no difference in the response when the virus was inoculated 9 hour before and at the same time of sensitization or even after that. Lymphocytes in peripheral blood of mice were markedly diminished in numbers when NDV was inoculated 48 and 24 hour before sensitization with SRBC, but they were slightly augmented when the virus was inoculated 9 hour before and at the same time of sensitization. When UV-inactivated or heat-inactivated NDV was injected to the mouse at the same time of sensitization with SRBC, DTH and rosette formation of spleen cells were slightly depressed. DTH and rosette formation in mice treated with crude-IF were generally depressed as com pared with those of control mice. These studies suggest that the NDV causes a significant depression of cell-mediated immunity, whereas the humoral immune response is not inhibited markedly, and that the depression of immune response by NDV infection may be caused by interferon produced by NDV and direct viral activity.

• Journal of Life Science
• /
• v.22 no.4
• /
• pp.552-558
• /
• 2012

Severe acute respiratory syndrome (SARS) is a severe respiratory infectious disease caused by a novel human coronavirus, SARS-CoV. The 3CL protease is a key enzyme in the proteolytic processing of replicase polyprotein precursors, pp1a and pp1ab, which mediate all the functions required for viral genomic replication and transcription. Therefore, this enzyme is a target for the development of chemotherapeutic agents against SARS. A large quantity of active SARS-3CL protease is required for development of anti-SARS agents. Here we have constructed overexpression vector for the production of the SARS-3CL protease. The gene encoding SARS-3CL protease was amplified using polymerase chain reaction and cloned into the pET29a expression vector, resulting in pET29a/SARS-3CLP. Recombinant SARS-3CL protease was successfully synthesized by the dialysis mode of the cell-free protein expression system, and purified by three-step fast protein liquid chromatography using HighQ and MonoP column chromatographies and Sephacryl S-300 gel filtration. In addition, the produced SARS-3CL protease was found to be an active mature form. This study provides efficient methods not only for the development of anti-SARS materials from natural sources, but also for the study of basic properties of the SARS-3CL protease.

• Research in Plant Disease
• /
• v.18 no.4
• /
• pp.391-395
• /
• 2012

To investigate the occurrence of viruses in peach, leaf samples were collected from peach trees in commercial orchard of six areas in Korea. Reverse transcription polymerase chain reaction (RT-PCR) was used to identify the presence of the following stone fruit viruses: Apple chlorotic leaf spot virus (ACLSV), Apple mosaic virus (ApMV), Prune dwarf virus (PDV), Prunus necrotic ringspot virus (PNRSV) and Plum pox virus (PPV). About 65.0% of the 515 samples were infected with ACLSV and PNRSV. Virus-like symptoms showing mosaic on leaves was observed in ACLSV infected peach trees. However, PNRSV infected peach trees showed no symptoms. These viral DNAs by sequence analysis were confirmed 4 ACLSV isolates and 3 PNRSV isolates. The Korean peach isolates of ACLSV and PNRSV showed 70-99% and 88-99% amino acid sequence identities, respectively, with those reported previously and their amino acid sequence identities with each other were approximately 95% and 88%, respectively. Phylogenetic analysis indicated that the Korean ACLSV isolates belong to the A group of ACLSV. The Korean PNRSV isolates reported in this study were grouped into I (PV32), II (PV96) and III (PE5) groups.

• Research in Plant Disease
• /
• v.9 no.3
• /
• pp.107-115
• /
• 2003

Chinese yam (Dioscorea opposita cv. Jang-Ma) plants showing necrotic mosaic symptom were collected from their growing fields in Andong, Euisong, Gunwi and Daegu, Korea. Direct negative stainning method by electron microscope showed filamentous particles of about 660 nm in length. Immunosorbent electron microscopy (ISEM) revealed filamentous particles of 660nm decorated with antiserum of Chinese yam necrotic mosaic virus (ChYNMV). The virues purified partially were used to isolate viral RNA as template for RT-PCR to amplify about 1.2 kbp of 3'-terminal region (coat protein, 3'-UTR) with ChYNMV specific and oligo-dT primers. Amino acids sequences of amplified CP genes revealed that the viruses shared 97.9% similarity with ChYNMV (AB044386) wh ich was known as the member of Macluravirus. So the viruses from Chinese yam (D. opposita cv. Jang-Ma) plants were identified as ChYNMV. Comparing the CP amion acid sequences of ChYNMV strains with other macluraviruses such as Cardamon mosaic virus (CdMV), Narcissus latent virus (NLV) and Maclura mosaic virus (MacMV) revealed that N-terminal was the most varialbe region and conserved regions were present within the genus Macluravirus.

• Journal of Embryo Transfer
• /
• v.25 no.1
• /
• pp.43-50
• /
• 2010

The specimens from 32 aborted fetus and 274 aborted cows were collected in 168 farms of Chonnam province from 2005 to 2008 and were tested the brucellosis. The results obtained are summarized as follows. In the 32 aborted fetus, bovine brucellosis was detected in 12 heads (37.5%), bovine viral diarrhea-mucosal disease was detected in 7 heads (19%), ainovirus infection was detected in 1 head (3.1%), and multi-infection of BVD and brucellosis was not detected, respectively. In the 306 cases of aborted fetus and cows, bovine brucellosis was detected in 44 heads (14%). Status of abortion were confirmed in 63 farms (38%) out of 168 farms from June to August. From the point of raising scale, studies found that 128 farms (76%) out of all raised under 20 heads. The incidence of abortion by brucellosis was mainly showed in 30 heads (68.1%) about 151~250 days of gestation. In the result of the 18 farms survey, the causes of infections were detected movement of infected cattle in 5 farms (28%), unknown cause in 12 farms (67%), and recurrence in 1 farm (5%). The results of this study suggest to take an advantage of the prevention and fundamental research for bovine brucellosis in Chonnam province.

• Korean Journal of Biological Psychiatry
• /
• v.1 no.1
• /
• pp.98-108
• /
• 1994

The etiology and pathophysiology of schizophrenia remain unknown. It has been postulated that infectious-autoimmune process may play a role in the pathogenesis of symptoms in some schizophrenic patients. Findings of altered interleukin(IL) regulation have been regarded as additional proof that schzophrenia has an infectious-autoimmune background. In the present study, we measured mitogen-stimulated production of and serum level of IL-$1{\beta}$, IL-2, IL-6 using ELISA in 16 neuroleptic-free schizophrenic patients and in 16 age, sex matched healthy controls. The results were as follows : 1) There was a significant decrease of IL-2 production in schizophrenic patients than in normal controls(respectively $1.90{\pm}0.13ng/m{\ell}$, $2.79{\pm}0.14ng/m{\ell}$, p<0.001). But there was no significant difference of IL-$1{\beta}$ production and IL-6 production between schizophrenic patients and normal controls. 2) There was a significant increase of serum level of IL-2 in schizophrenic pateitns than in normal controls(respectively $184.8{\pm}12.8pg/m{\ell}$, $104.2{\pm}34.2pg/m{\ell}$, p<0.01). Serum level of IL-$1{\beta}$ was partially detected in both groups and serum level of IL-6 was not detected in both groups. 3) There was no significant differences of IL-$1{\beta}$, -2, -6 production & serum level of IL-2 according to male vs female, paranoid type vs undifferentiated type, drug-naive group vs drug-free group in schizophrenic patients. 4) There was significant correlation between IL-$1{\beta}$ and IL-6 production(r=0.86, p<0.001). No correlation between IL-$1{\beta}$, -2, -6 production, serum level of IL-2 and age, duration of illness, and BPRS score was found. It has been suggested that the low lymphocyte production of IL-2 in the patients with autoimmune disease occurs because the T cells are activated and lymphocyte-derived IL-2 has been released into the serum. The authors suggest that decreased IL-2 production in our schizophrenic patients is due to increased IL-2 serum level in those patients. Thus our finding of low IL-2 production and high serum level of IL-2 in our schizophrenic patients is compatible with the possibility that our patients have an autoimmune process. Further study on relationship between IL alteration and other immunological abnormalities(the presence of serum autoantibody and of anti-brain antibody, $CD4^+$, $CD8^+$ cell index, etc) in schizophrenic patients will be warranted.

• Journal of Preventive Medicine and Public Health
• /
• v.43 no.2
• /
• pp.109-116
• /
• 2010

Objectives: The pandemic of novel influenza A (H1N1) virus has required decision-makers to act in the face of the substantial uncertainties. In this study, we evaluated the potential impact of the pandemic response strategies in the Republic of Korea using a mathematical model. Methods: We developed a deterministic model of a pandemic (H1N1) 2009 in a structured population using the demographic data from the Korean population and the epidemiological feature of the pandemic (H1N1) 2009. To estimate the parameter values for the deterministic model, we used the available data from the previous studies on pandemic influenza. The pandemic response strategies of the Republic of Korea for novel influenza A (H1N1) virus such as school closure, mass vaccination (70% of population in 30 days), and a policy for anti-viral drug (treatment or prophylaxis) were applied to the deterministic model. Results: The effect of two-week school closure on the attack rate was low regardless of the timing of the intervention. The earlier vaccination showed the effect of greater delays in reaching the peak of outbreaks. When it was no vaccination, vaccination at initiation of outbreak, vaccination 90 days after the initiation of outbreak and vaccination at the epidemic peak point, the total number of clinical cases for 400 days were 20.8 million, 4.4 million, 4.7 million and 12.6 million, respectively. The pandemic response strategies of the Republic of Korea delayed the peak of outbreaks (about 40 days) and decreased the number of cumulative clinical cases (8 million). Conclusions: Rapid vaccination was the most important factor to control the spread of pandemic influenza, and the response strategies of the Republic of Korea were shown to delay the spread of pandemic influenza in this deterministic model.

• Research in Plant Disease
• /
• v.16 no.3
• /
• pp.247-253
• /
• 2010

Apple scar skin viroid (ASSVd) is one of the smallest viral pathogens infecting fruits, especially apple, and causes a significant damage to fruit trees. ASSVd usually induced the skin-dapple ring symptoms, but in 'Fuji' varieties, corked spot were occurred on the fruit skin in 2009. This new symptom will be of great helpful to diagnosis ASSVd in sight. ASSVd was surveyed in apple and pear from 2009 to 2010 in Korea, and ASSVd was identified in 20 out of 1,193 trees. The infection rate was 1.7%. To screen the infectivity of ASSVd among apple cultivars, real-time RT-PCR was applied followed by designing of ASSVd specific primers based on highly conserved regions of several ASSVd isolates including Korean isolate. NADH dehydrogenase subunit 5 (nad 5) gene, which is mRNA of the mitochondrial gene, was used for internal control. In this study, ASSVd infected apples were classified into 12 groups depending on different symptoms and symptom severity (scaring, rusting or malformation). Taken together, this study suggested that real-time PCR analysis was more sensitive to detect the low copy of ASSVd on early viroid infected apple skins than regular RT-PCR method.

• Research in Plant Disease
• /
• v.23 no.3
• /
• pp.262-267
• /
• 2017

Throughout year 2015 to 2016, 101 proso millet and 200 sorghum samples were collected from five provinces in South Korea. The samples were subjected to paired-end RNA sequencing and further analyzed by RT-PCR. The results indicated that Rice black-streaked dwarf virus (RBSDV) was detected from sorghum collected in Gyeongsang province. The other four viruses, including RBSDV, Rice stripe virus (RSV), Barley virus G (BVG), and Cereal yellow dwarf virus (CYDV), were detected from proso millet. Among four viruses, both RSV and RBSDV were identified high frequency from proso millet collected from Gyeongsang province. Otherwise, BVG was nearly equally identified from five provinces, suggesting that the virus was supposedly widespread nationwide. RBSDV was first identified from both proso millet and sorghum in South Korea. The other virus annotated CYDV identified proso millet was shown to have relatively low identities compared to CYDV previously reported, suggesting that the virus might be new member of Polerovirus.