• Proceedings of the Microbiological Society of Korea Conference
• /
• 2000.05a
• /
• pp.23-36
• /
• 2000

Japanese encephalitis virus (JEV) is the causative agent of a mosquito-borne encephalitis and is transmitted to human via persistently infected mosquito vectors. Although the virus is known to cause only acute infection, there were reports that showed neurological sequelae, latent infection in peripheral mononuclear cells, and recurrence of the disease after acute encephalitis. Innate resistance of certain cell lines, abnormal SN1 expression of the virus, and anti-apoptotic effect of cullular bcl-2 have been suggested as probable causes of JEV persistence even in the absence of defective interfering (DI) particles. Although possible involvement of DI particles in JEV persistence was suggested, neither has a direct evidence for DI presence nor its molecular characterization been made. Two questions asked in this study are whether the DI virus plays any role in JEV persistent infection if it is associated with and what type of change(s) can be made in persistently infected cells to avoid apoptosis even with the continuous virus replication, DI-free standard stock of JEV was infected in BHK-21, Vero, and SW13 cells and serial high multiplicity passages were performed in order to generate DI particles. There different-sized DI RNA species which were defective in both structural and nonstructural protein coding genes. Rescued ORFs of the DI genome maintained in-frame and the presence of replicative intermediate or replicative form RNA of the DI particles confirmed their replication competence. On the other hand, several clones with JEV persistent infection were established from the cells survived acute infections during the passages. Timing of the DI virus generation during the passages seemed coincide to the appearance of persistently infected cells. The DI RNAs were identified in most of persistently infected cells and were observed throughout the cell maintenance. One of the cloned cell line maintained the viral persistence without DI RNA coreplication. The cells with viral persistence released the reduced but continuous infectious JEV particle for up to 9 months and were refractory to homologous virus superinfection but not to heterologous challenges. Unlike the cells with acute infection these cells were devoid of characteristic DNA fragmentation and JEV-induced apoptosis with or without homologous superinfection. Therefore, the DI RNA generated during JEV undiluted serial passage on mammalian cells was shown to be biologically active and it seemed to be responsible, at least in part, for the establishment and maintenance of the JEV persistence in mammalian cells. Viral persistence without DI RNA coreplication, as in one of the cell clones, supports that JEV persistent infection could be maintained with or without the presence of DI particles. In addition, the fact that the cells with JEV persistence were resistant against homologous virus superinfection, but not against heterologous one, suggests that different viruses have their own and independent pathway for cytopathogenesis even if viral cytopathic effect could be converged to an apoptosis after all.

• Korean Journal of Microbiology
• /
• v.31 no.1
• /
• pp.17-21
• /
• 1993

Eight strains of Bacillus thuringiensis were isolated from soil in Korea and characterized. The isolates were named HL-24, HL-25, HL-33, HL-34, HL-35, HL-38, HL-39, HL-40. Strains HL-24 and HL-25 produced irregular parasporal crystals, HL-33 and HL-35 produced bipyramidal crystals, and others were round form in their cells. The biochemical characteristics of the eight isolates were only minor different in specific characteristics to the known serotypes of Bacillus thuringiensis. The HL-25, HL-33 and HL-34 strains showed resistances to cephalothin, colistin and penicillin G, and HL-39 and HL-40 strains were resistant to penicilin G. The strains of HL-24, HL-25, HL-33 and HL-34 were toxic to Bombyx mori lavae and HL-24, HL-25, HL-38, HL-39 and HL-40 strains killed Culex pipiens 3rd instar larvae. The HL-24 and H25 strains showed lethal activity against two kinds of the larvae, however lethality against mosquito larvae was low.

• Korean journal of applied entomology
• /
• v.51 no.4
• /
• pp.305-312
• /
• 2012

This study was conducted to elucidate the seasonal prevalence of adult mosquitoes and occurrence of anopheline larvae in Gimpo, Gyeonggi province, Republic of Korea. Sampling of adult mosquitoes was carried out 18 times from May to September in 2008, using light traps at six sites. A total of 48,919 individuals belonging to 16 species and 8 genera were collected. Aedes vexans nipponii (43%) was the most frequently collected, followed by Anopheles sinensis (34%) and Culex tritaeniorhynchus (14%). The seasonal prevalence of anopheline mosquitoes had a different occurrence compared to that of Cx. tritaeniorhynchus. Anopheline larvae were collected using a standard dipper (size = of 350 ml) at eight habitat types of 203 point locations. Anopheline larvae were confirmed from 138 points (63%). The average larval population per dipper was highest in the lotus plantation (6.9 individuals), followed by irrigation channel (4.5 ind.), dropwort field (3.4 ind.), fallow field (3.1 ind.), paddy field (1.8 ind.), swamp (1.4 ind.), and stream (0.2 ind.). There was no significant relationship observed between larval density and DO, pH, salinity, or distance from blood meal hosts (cowshed, pigsty, chicken-house). In the results of average nearest neighbor analysis (ANNA), the distribution of whole points for mosquito larval collection was clustered, and points with over 4.0 larvae per dipper were randomly distributed. Within the study area Haseong-myeon, those points where over 3.0 larvae were collected were of a dispersed distribution.

• Parasites, Hosts and Diseases
• /
• v.58 no.5
• /
• pp.551-558
• /
• 2020

The flaviviruses are small single-stranded RNA viruses that are typically transmitted by mosquitoes or tick vectors and are etiological agents of acute zoonotic infections. The viruses are found around the world and account for significant cases of human diseases. We investigated population of culicine mosquitoes in central region of Korean Peninsula, Incheon Metropolitan City and Hwaseong-si. Aedes vexans nipponii was the most frequently collected mosquitoes (56.5%), followed by Ochlerotatus dorsalis (23.6%), Anopheles spp. (10.9%), and Culex pipiens complex (5.9%). In rural regions of Hwaseong, Aedes vexans nipponii was the highest population (62.9%), followed by Ochlerotatus dorsalis (23.9%) and Anopheles spp. (12.0%). In another rural region of Incheon (habitat of migratory birds), Culex pipiens complex was the highest population (31.4%), followed by Ochlerotatus dorsalis (30.5%), and Aedes vexans vexans (27.5%). Culex pipiens complex was the predominant species in the urban region (84.7%). Culicine mosquitoes were identified at the species level, pooled up to 30 mosquitoes each, and tested for flaviviral RNA using the SYBR Green-based RT-PCR and confirmed by cDNA sequencing. Three of the assayed 2,683 pools (989 pools without Anopheles spp.) were positive for Culex flaviviruses, an insect-specific virus, from Culex pipiens pallens collected at the habitats for migratory birds in Incheon. The maximum likelihood estimation (the estimated number) for Culex pipiens pallens positive for Culex flavivirus was 25. Although viruses responsible for mosquito-borne diseases were not identified, we encourage intensified monitoring and long-term surveillance of both vector and viruses in the interest of global public health.

• Korean journal of applied entomology
• /
• v.61 no.1
• /
• pp.267-274
• /
• 2022

Portable and vehicle thermal fogs were tested using etofenprox, bifenthrin, and deltamethrin diluted with diesel oil, kerosene, and water against domestic vector mosquitoes, Aedes albopictus, Anopheles sinensis s.l., Culex pipiens, and Culex tritaeniorhynchus. The female mosquitoes were confined in small cages suspended on poles at progressively greater distances from the fog release point at an open field. The average mortality rates of four vector mosquitoes to the three insecticides were 52.0% and 64.0% at a portable thermal fogs diluted with diesel oil and water within a 10 m distance, respectively. A vehicle thermal fog had a mean mortality of 34.8% of the females to the insecticides diluted with diesel oil within 50 m. The mortality rates were not significantly different among all the tested distances. At a dilution solvent test, the mortality of the females to the insecticides diluted with kerosene was 1.9 times higher than that of diesel oil.

• Korean Journal of Veterinary Service
• /
• v.41 no.3
• /
• pp.165-169
• /
• 2018

This survey is performed for the vector mosquitoes including of Japanese encephalitis, Malaria and West niles virus. Black light traps were installed in 5 sites (Sejong lake, Janggun-myeon, Jeonui-myeon, Yeongi-myeon, Bukang-myeon). Mosquitoes were collected twice every week from five collection sites using a black light trap from May to September. A total of 10 species belonging to 4 genera, 14,234 female mosquitoes were collected and identified as vector mosquitoes. Among ten mosquito species, Culex pipiens complex was the most commonly mosquitoes (6,163 individuals, 43.3%). The greatest number of Culex pipiens pallens was trapped in the first week of July. A total of 115 pools from 14,234 mosquitoes were prepared according to their species, collection date and site. We have screened infection of virus in mosquitoes. All of virus were not detected in mosquitoes. Our findings confirm that population and first appearance time of vectors mosquitoes and virus infection in Sejong city.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.8 no.2
• /
• pp.257-266
• /
• 2007

In many multimedia applications, image compression is required to substantially reduce the amount of image data. This compression, however, sometimes brings artifacts. Typical artifacts are blocking artifacts and mosquito noise in DCT-coded images, and ringing artifacts around edges in wavelet-coded images. We propose a new directional postprocessing algorithm, which includes detection of the edge direction, interpolation scheme, and directional nonlinear filtering, to enhance the quality of decoded images. Simulation results show that the proposed algorithm is as effective as or more effective than other nonlinear filtering techniques.

• IMMUNE NETWORK
• /
• v.12 no.2
• /
• pp.48-57
• /
• 2012

Acute viral encephalitis caused by neurotrophic viruses, such as mosquito-borne flaviviruses, is an emerging and re-emerging disease that represents an immense global health problem. Considerable progression has been made in understanding the pathogenesis of acute viral encephalitis, but the immune-pathological processes occurring during the progression of encephalitis and the roles played by various molecules and cellular components of the innate and adaptive systems still remain undefined. Recent findings reveal the significant contribution of Toll-like receptors (TLRs) and regulatory $CD4^+$ T cells in the outcomes of infectious diseases caused by neurotrophic viruses. In this review, we discuss the ample evidence focused on the roles of TLRs and $CD4^+$ helper T cell subsets on the progression of acute viral encephalitis. Finally, we draw attention to the importance of these molecules and cellular components in defining the pathogenesis of acute viral encephalitis, thereby providing new therapeutic avenues for this disease.

• The Korean Journal of Zoology
• /
• v.3 no.1
• /
• pp.9-12
• /
• 1960

The present status of insecticide resistance of Korean mosquitoes is still unknown. The experiment cited below is a part of our series of resistance tests on Korean mosquitoes. The test was carried out during the summer of 1959 to ascertain the degree of resistance of Culex pipiens to insecticides currently used. Culex pipiens eggs were collected from ditches in Seoul City and reared in laboratory with media consisted of the following : Distrilled water 1.0 liter, Magnesium sulfate (MgSO$_4$.7$H_2O$) 1.0gram , Calcium sulfate (CasO$_4$.2$H_2O$) 0.5gram ; Sodium cholride 0.5 gram. A Sufficient amount of beer yeast was also used as a larvar food. Late third and early fourth instar larvae were selected for testing. The results are summarized in the following. THe LC-50 of Culex pipiens to insecticides were 0.061 ppm in p, p-DDT , 0.045 ppm in ${\gamma}$-BHC and0.029 ppm in malathion. Comparing these with LC-50 doses of Orlando laboratory strain, it can be pointed out that the present resistance of Seoul strain shows about a ten-fold increase in DDt, and a fourfold increase in ${\gamma}$-BHC . The resistance development of the Seoul strain has, however, not arisen so markedly as compared with data observed in other parts of Far Eastern areas received heavy insecticidal operations.

• Journal of environmental and Sanitary engineering
• /
• v.17 no.1
• /
• pp.36-40
• /
• 2002

The purpose of study was to suggest an investigation of citizen's attitude on harmful insects in house. This study was consisted of four parts, such as basic investigation (housing shape, housing material, the period of house constructed, a cleaning condition), condition of kitchen, condition of living room condition of bathroom. The environmental pollution was increased by the development of industry and urbanization in modern. And also the clean of house has related with air quality such as pollutants and harmful insects etc. Because dwelling shape of urban come to be crowded, shut tightly and high buildings, the air quality of indoor was gradually polluted by several irregular cause. In one of housing pollution, the harmful insects was important any other than indoor air pollution. The problems of kitchen were the odor of food waste, discharge system of sewage and harmful insects. The important issues of living room were mold and construction materials, then important them of bathroom were easing nature and discharge system of sewage. A kind of the harmful insects in house investigated cockroach> mosquito> ant>fly. Finally, it appeared that the control of harmful insects can be applied to the improvement of indoor air pollutant which are difficult to be controlled in house.