• Asian-Australasian Journal of Animal Sciences
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• 제14권2호
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• pp.163-169
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• 2001

Despite the high potency of the retrovirus vector system in gene transfer, one of the main drawbacks of has been difficulty in preparing highly concentrated virus stock. Numerous efforts to boost the virus titer have ended in unsatisfactory results mainly due to fragile property of retrovirus envelope protein. In this study, to overcome this problem, we constructed our own retrovirus vector system producing vector viruses encapsulated with VSV-G (vesicular stomatitis virus G glycoprotein). Concentration process of the virus stock by ultracentrifuge did not sacrifice the virus infectivity, resulting in more than 108 to 109 CFU (colony forming unit) per ml on most of the target cell lines tested. Application of this high-titer retrovirus vector system was tested on chicken embryos. Injection of virus stock beneath the blastoderms of pre-incubated fertilized eggs resulted in chick embryos expressing E. coli LacZ gene with 100% efficiency. Therefore, our results suggest that it is possible to transfer the foreign gene into chicken embryo using our high-titer retrovirus vector.

• Journal of Microbiology
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• 제34권3호
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• pp.263-263
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• 1996

Infection of fish cells with IHNV resulted in gradual increase in cytosolic free $Ca^{2+}$ concentration $([Ca^{2+}]_i)$ in CHSE, gradual decrease in $[Ca^{2+}]_i$ in FHM, and no significant change in RTG cells. The degree of $[Ca^{2+}]_i$ increase or decrease was dependent on the amount of infectious virus, and these $[Ca^{2+}]_i$ variations were maximal at 16 hours after virus infection (p. i.) in both cell lines. When the fish cells were infected with inactivated IHNV, evident variation in $[Ca^{2+}]_i$ was not observed. Thus, infectivity of IHNV appears to correlate with changes in $[Ca^{2+}]_i$ in virus-infected cells. These IHNV-induced $[Ca^{2+}]_i$ changes were partially blocked by cycloheximide, but not affected by cordycepin. It seems to be that virus-induced $Ca^{2+}$ variations were more related with protein synthesis than RNA synthesis. Various $Ca^{2+}$ related drugs were used in search for the mechanisms of the $[Ca^{2+}]_i$, changes following IHNV infection of CHSE cells. Decreasing extracellular $Ca^{2+}$ concentration or blocking $Ca^{2+}$ influx from extracellular media inhibited the IHNV-induced increase in $[Ca^{2+}]_i$, in CHSE cells. Similar results were obtained with intracellular $Ca^{2+}$ blockers. Thus it is suggested that both the extracellular and the intracellular $Ca^{2+}$ sources are important in IHNV-induced $[Ca^{2+}]_i$ increase in CHSE cells.

• Preventive Nutrition and Food Science
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• 제7권2호
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• pp.168-173
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• 2002

Gastrointestinal infections kill over two million people each year, and pathogen contamination of livestock causes many cases of food poisoning. Two candidate intestinal probiotic strains, L. rhamnosus GR-1 and L. fermentum RC-14 were found to inhibit the growth of Salmonella typhi, Shigella dysenteriae, E. coli O157:H7, Listeria monocytogenes, L. innocua, Enterococcus faecalis, and Bacteroides fragilis. In a series of mouse experiments, L. rhamosus GR-1 and L rhamnosus GG protected against S. typhimurium infection and translocation to the liver and spleen, reduced mortality and induced intestinal phagocytic and immunoglobulin responses. In a second series of experiments, the combination of L. rhamnosus GR-1 and L. fermentum RC-14 was superior to L. rhamnosus GG and placebo in protecting the mice from the lethal effect of salmonella. In summary, the use of combinations of probiotic lactobacilli as dietary supplements or foods could be considered for people at high risk of salmonella intestinal infection. Given the post-infection complications that can arise, such natural methods warrant further exploration especially given the increasing problem of antibiotic resistance and the lack of alternative measures available to many developing countries.

• The Plant Pathology Journal
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• 제18권3호
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• pp.121-125
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• 2002

This study was conducted to determine the causal virus that naturally infected hollyhock (Althaea rosea) plant showing mild mosaic symptom in 1999. Flexuous virus particles were found in the cytoplasm of plant tissue from infected hollyhock under transmissible electron microscopy. A virus from the genus Potyvirus under the family Potyviridae was isolated and was maintained on Chenopodium quinoa for three passages. Chlorotic local legions were used to inoculate 20 species of indicator plants. The virus infected all the tested cucurbit plants, but failed to infect Nicotiana benthamiana. Based on the host range test and RT-PCR analysis, the potyvirus was identified as a strain of Zucchini yellow mosaic virus-A (ZYMV-A), one of the major pathogens of cucurbits. Infectivity analysis showed that ZYMV-A induced faster systemic symptom than ZYMV-Cu on squash and other cucurbit plants, suggesting that ZYMV-A was a more severe strain. To better characterize ZYMV-A, Western blot assay was carried rout to the coat protein (CP) of the virus using ZYMV-specific antiserum with ZYMV-Cu and other potyviruses. The CP of the virus reacted strongly with the antiserum against ZYMV, and other tested antisera did not react with the CP of ZYMV-A. Results strongly suggest that the potyvirus infecting hollyhock was a novel strain of ZYMV. This is the first report on ZYMV as the causal virus infecting hollyhock in Korea.

• 대한수의학회지
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• 제39권4호
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• pp.751-759
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• 1999

Plaque characteristics of porcine reproductive and respiratory syndrome (PRRS) virus isolates were examined using MARC-145 line cells. The plaque morphology of PRRS virus isolates was variable in size and heterogenic in population. Upon serial passages of the PRRS virus isolates on MARC-145 tells, heterogeneity was maintained but numbers of the large plaque size virus were increased with certain isolates. A PRRS virus isolate with variable plaque sizes was subcloned into 2 populations : small plaque ($H_S$) and large plaque ($H_L$) viruses. Growth kinetics of the subclones were then determined in MARC-145 cells, and production of the structural polypeptides was analyzed by SDS-PAGE. In a comparison of the growth kinetics, the $H_S$ virus showed higher infectivity titers during the first 48 hours but slower to reach the peak titier than $H_L$ virus did. In a nucleotide sequence comparison, differences of 4 nucleotides in open reading frames 5-6 gene were found between $H_S$ and $H_L$ viruses. Both the $H_S$ and $H_L$ clones produced 5 polypeptide bands with molecular weights of 15, 19, 26, 36 and 42 kD. The 5 bands were detected at 48 hours postinoculation (PI) with antisera to $H_L$ and another large plaque virus ($W_L$) and at 72 hours PI with $H_S$ virus antiserum. The present results demonstrate differences of biologic and molecular characteristics between the two PRRS virus plaque clones.

• Parasites, Hosts and Diseases
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• 제27권3호
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• pp.197-202
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• 1989

이 연구는 흰쥐, 개 및 고양이 숙주에 대한 이락촌폐흡충(Paragonimus iloktsuenensis)의 감염력 및 충체 성장 발육을 비교함으로써 개 및 고양이의 숙주 적합성을 알아보고 나아가 이 흡충 의 인체 감염 가능성을 추정해 보고자 실시하였다. 섬진강 하구산 말똥게(Sesarma dehaani)로부터 분리, 수집한 이락촌폐흡충의 피낭유충을 흰쥐, 개 및 고양이에 경구 감염시킨 후 42일을 기준으로 충체를 회수하였으며, 감염 후 42일에 회수한 충체를 유대로 하여 성장 발육을 비교하였다. 감염 후 42일에 흰쥐, 개 및 고양이에서 충체 회수율은 각각 평균 53.4%, 21.9% 및 12.7%이었으나 회수된 충체의 크기가 각각 평균 6.3×3.2mm, 6.3×3.0mm 및 6.2×3.5mm로 차이가 없었고 충체 발육 상에 있어서도 차이가 없었다. 이 연구의 결과는 이탁촌폐흡충의 종숙주로서 개 및 고양이가 충분히 가능함을 나타내었다.

• Parasites, Hosts and Diseases
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• 제47권2호
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• pp.131-138
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• 2009

The present study surveyed the prevalence of natural infection of the sheep esphagus muscle with sarcocysts of Sarcocystis ovicanis and examined induction of protective immunity using UV-attenuated sporocysts. The overall prevalence of natural infection of the sheep was 95%. Infectivity of the collected sarcocysts was confirmed by shedding of sporulated oocysts after feeding infected esophageal tissues to dogs. To induce protective immunity, lambs were immunized 3 times (once a week) with $1.5{\times}10^4$ sporocysts exposed to UV-light for 30min (UV-30 group) or 60 (UV-60 group) min and then challenged with $1.5{\times}10^4$ normal sporocysts at the 3rd week post the 1st vaccination. These lambs showed high survival and less clinical signs of sarcocystosis than normal infected lambs. The attenuated sporocysts produced abnormal cysts; small in size and detached from the muscle fiber. These abnormalities were more obvious in UV-60 group than UV-30 group. Also, the $IFN-{\gamma}$ level and lymphocyte percentage were increased while the total leukocyte count was decreased in the UV-60 group compared with other groups. The high level of $IFN-{\gamma}$ may be an evidence for the induction of Th1 responses which may have protective effect against a challenge infection.

• 한국가축번식학회지
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• 제25권2호
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• pp.171-180
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• 2001

형질전환 가금의 생산에 있어서 retrovirus vector를 이용하는 방법은 다양한 종류의 표적세포에 대하여 retrovirus 고유의 감염성에 의한 외래 유전자의 전이가 용이하고, 전이된 유전자가 진정염색질 영역 내로 선택적으로 도입될 수 있으며 유전적으로 안정성을 나타내므로 매우 효과적인 방법이다. 그러나 가금에서는 초기 배발달에 의한 급격한 세포의 수적 증가로 인해 고감염성의 virus의 획득이 요구되므로, 이를 위하여 virus stock의 농축에 있어 보다 안정적이고 pantropic인 vesicular stomatitis virus (VSV G) glycoprotein를 envelope로 가지는 pseudotyped retrovirus vector system을 이용하였으며, marker gene으로 eGFP gene이 발현되는 retrovirus를 생산하였다. 이 virus를 이용하여 여러 가지 표적세포와 primary culture한 CEF세포를 감염시켜 GFP의 발현을 확인하였으며, 농축한 virus stock은 stage X의 계란을 선택하여 windowed egg를 제작한 후 배하층에 주입하였다. 형질전환 닭은 정상 발생한 닭에 비하여 저조한 발생율을 보였으나 PCR을 이용하여 외래 유전자의 도입을 확인한 결과 100%인 것으로 나타났다. 또한 한 개체 내에서 유전자의 도입이 폐, 간, 정소, 소장 등의 여러 장기에서 확인되었다.

• 한국작물학회지
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• 제33권4호
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• pp.380-385
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• 1988

The present study was conducted to evaluate agronomic characters of the soybean germplasm which was collected from the sites covering whole areas of southern Korean peninsula. A total of 2,748 Korean native soybeans was grouped for fruiting period and in this group frequency distribution of the important agronomic characters and relationships among the characters were determined. The results obtained were summarized as follows; The soybean germplasm was comprised of SeoulㆍKyonggi-do 7.5%, Kangwon-do 13.3%, Chungchongbuk-6.6%. Chungchongnam-do 12.3%, Chollabuk-do 10.7%, Chollanam-do 12.6%, Kyongsangbuk-do 20.8%, Kyongsangnam-do 15.3% and Cheju-do 0.6% in number of collections. Frequency distribution of the germplasm for fruiting period was 0.14% in Group I (below 55 days). 1.67% in Group II (56-60 days), 10.58% in (Group III(61-65 days), 23.18% in Group IV(66-70 days), 25.91% in Group V(71-75 days) 19.79% in Group Ⅵ(76-80 days), 15.1% in Group Ⅶ(81-85 days) and 3.6% in Group Ⅷ(over 85 days). The lines over 70 days in fruiting period were as much as 64.4% of germplasm. The fruiting period varied largely from 45 days to 91 days. Fruiting period was positively correlated to seed weight, days to maturity, days to flowering, plant height and number of branches per plant, respectively. While. it was negatively correlated to number of pods, lodging and virus infectivity, repectively, and in particular negative correlation was shown significantly between yield and fruiting period. Average yield was very high as much a 1.389kg/ha in fruiting period Group I, and decreased with increment of fruiting period, 1.400kg/ha in Group II. 1.384kg/ha in Group III. 1,299kg/ha in Group IV, 1,197kg/ha in Group V, 1,117kg/ha in Group Ⅵ, 967kg/ha in Group Ⅶ and 832kg/ha in Group Ⅷ.

• 대한가정학회지
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• 제30권3호
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• pp.91-99
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• 1992

Cell structure is based on proteins. Since the antibody is proteous substance, the continous low protein feeding decreases the resistance of host against pathogenic agents. The present study was designed to investigate the infectivity of protozoa to rats which were fed with variously prescribed diets. Experimental group was divided into 4 groups according to the level of casein in the diet, group I: casein 0%, group II: casein 5%, group III: casein 15%, group IV: casein 30%. Each animal was fed for 5 weeks followed by inoculation of protozoa in cecum and sacrified each 1 week later of the infection. Each diet group, non infected with protozoa was recognized as the control. Result are summerized as follows : 1. All the rats of group I died in 2∼4 weeks and 2 of 12 rats in group II were also died in the period. 2. The growth rate and FER were high in group III and IV compared with group II. Therefore low protein feeding decrease growth and feed efficaly ratio(FER). 3. The pH of caecal contents between the infected group and control showed no difference, but the values of group III and IV were higher than the group II. Low pH of the caecal contents provides a suitable condition for determining their susceptibility to Entameoeba histolytical trophozoite. 4. Amounts of serum total protein in group II, III and IV showed no significant difference with the control and infected group, but amounts in group III and IV were higher than the group II. Therefore, continuous low protein feeding decrease serum total protein. 5. Albumin, ${\alpha}$1, gloulin, ${\alpha}$2 globulin, ${\beta}$ globulin, ${\gamma}$ gloulin of group III and IV were all high to compare than the group II. Albumins of group III and IV of control was higher than infected group, but there was no difference in ${\gamma}$ globulin between the infected and control group.