• Korean Journal of Veterinary Service
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• v.21 no.3
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• pp.255-260
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• 1998

Since bovine leukosis caused considerable economic loss to the dairy industry, seroepidemiologi-cal survey on bovine leukosis was carried out for the dairy herds in Kyunggi province. 1. When compared the results of immunodifussion test with those of enzyme-linked immunosorbent assay(ELISA) for 94 dairy herds sera, the relationship between the immunodifussion test and ELISA were showen high corresponding rate with sensitivity(97.5%) and specificity(92.6%). 2. In immunodiffusion test for bovine leukosis virus (BLV) antibody in 570 dairy cattle from 30 herds, mean positive rate for BLV antibody was 28.2%. The positive rate by districts were 16.5% in central, 35.4% in east, 17.3% in west, 29.1% in south, 31.6% in north, 43.7% in northeast. 3. When the results of serological studies was analyzed by age groups, the number of positive was increased gradually with the advanced in age of herds. The highest positive rate was found in the age over 6 years. 4. Of 30 dairy herds examined, 5 herds(16.7%) have no reactions against BLV antigen while 15 herds (50%) showed the range of 1∼5 positive cattle and 5 herds(16.7%), the rang of over 11 positive cattle.

• Korean Journal of Veterinary Research
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• v.22 no.1
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• pp.63-66
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• 1982

Authors encountered a case of bovine viral leukosis in a young cattle (10 months old) with the following findings; Main clinical symptoms observed were emaciation, digestive disorder, and marked enlargement of superficial lymph nodes. Biopsied specimen of the lymph nodes revealed characteristic histological picture of bovine leukosis. A severe degree of leukocytosis (108,000/cmm) accompanied by marked lympocytosis (96%=103,680/cmm) was detected from the hematological examination of peripheral blood. Most of the lympocytes(94%=101,520) were large-sized, immature, and abnormal in their morphology. In addition, a pronounced anemia (1.78 million/cmm) without regenerative evidence of erythrocyte was noted. The serum of the patient showed positive reaction against gp antigen of bovine leukosis virus in agar-gel diffusion test.

• Korean Journal of Veterinary Service
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• v.29 no.2
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• pp.89-96
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• 2006

Bovine viral leukosis is a viral disease of cattle characterized by the development of tumors in the lymphatic tissue. A female Holstein, 3-year-old, was submitted for diagnosis at the Diagnostic laboratory, Chonbuk National University. Clinical sign of the affected animal showed emaciation, enlargement of superficial lymph node and mild diarrhea. Remarkable lesions were enlargement of many internal lymph nodes. Histopathology revealed excessive neoplastic lymphoid cells characteristic of BVL infection. Subsequently, serums from all cattle were collected and serological examination was done where a 85% seropositive rate was detected using ELISA test. ELISA method showed a comparatively 75% higher detection rate than the agar gel immunodiffusion (AGID) test (85% vs 40%). Serologically positive cattle were variably detected in all ages from under 1 year to over 6 year of age. Hematological examination consistently showed leukocytosis and a differential lymphocytosis of seropositive cattle. Detailed comparative pathological and serological data diagnosed the presence of bovine viral leukosis.

• Korean Journal of Veterinary Research
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• v.30 no.3
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• pp.333-341
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• 1990

To investigate bovine leukosis virus (BLV) infection in the cattle rearing in a dairy farm where a case of bovine lymphosarcoma had been identified several years ago, the 196 Holstein cattle including newborn calves to 12 years of age were tested. The BLV antibody test and peripheral lymphocyte count for bovine leukosis were carried out by the immunodiffusion (ID) test and Bendixen's Kep. These tests were performed 2 to 4 times at the interval of 3 to 5 months. The observed results were as follows: 1. The positive rates of BLV-antibody in the 1st, the 2nd, the 3rd and the 4th tests were 23.3%, 28.1%, 49.0% and 55.7%, respectively. The conversion rates from negative to positive in the 2nd, the 3rd and the 4th tests were 8.9%, 41.4%, and 20.0%, respectively. Results showed that the highest conversion rate was observed at the 3rd test which was conducted after winter. The highest positive rate by ID test were observed in 4 year old cattle in the 1st and 2nd tests, and in 2 year old herd in the 3rd and 4th tests. 2. In hematological test by Bendixen's Key, the positive and suspicious rates in the 1st, the 2nd, the 3rd and the 4th tests were 5.8 and 7.8%, 8.3 and 6.6%, 8.7 and 10.1%, 10.8 and 19.6% respectively. Results showed that the positive and. suspicious rates increased in course of time. 3. 70 to 100% of the positive cattle in hematological test were positive for BLV-antibody test. All of 13 cattle with persistent lymphocytosis (PL) were also positive for BLV-antibody, indicating the high relationship between PL and BLV-antibody. 4. The number of total leukocytes and absolute lymphocytes in the BLV-antibody positive cattle appeared significantly higher than those of the negative cattle. The markedly increased cell counts were observed in the cattle over one year old. 5. The mean of total leukocytes and absolute lymphocytes in the negative cattle for BLV-antibody increased slightly after sero-conversion into positive. 6. In the clinical examinations during experimental periods, none of the 72 positive cattle for BLV-antibody showed any lesions for bovine leukosis.

• Korean Journal of Veterinary Service
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• v.30 no.4
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• pp.551-555
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• 2007

A slaughtered 3 years old cow was diagnosed as bovine leukosis by postmortem inspection, agar gel immunodifusion (AGID) test, and polymerase chain reaction (PCR). It showed no special clinical signs except emaciation. Grossly, we observed enlargement of mediastinal and pelvic lymph nodes, and tubercle -like mass on pleura and lung surface, and masses on right atrium and ventricle.

• Korean Journal of Veterinary Research
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• v.30 no.3
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• pp.343-348
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• 1990

Total 51 calves born from both 28 seropositive and 23 seronegative dams were subjected to study both prenatal and postnatal infections of bovine leukemia virus (BLV), and the duration of passive colostral antibody by means of immunodiffusion (ID) test. All calves were tested for precolostral and postcolostral periods by 16 months of age. The results were as follows: 1. Of 28 precolostral sera of the calves born from infected dams, one appeared positive, indicating in utero BLV infection from the dam. 2. BLV-antibody test for the postcolostral sera of the calves born from seropositive or seronegative dams showed that the colostral antibody of the calves disappeared from 2 to 6 months of age, and the increase of the number of seropositive calves initiated from 3 to 4 months of age indicated postnatal infection.

• 종축개량
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• v.12 no.1 s.71
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• pp.112-114
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• 2007

• Proceedings of the Korean Society of Veterinary Pathology Conference
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• 2003.10a
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• pp.50-50
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• 2003

Enzootic bovine leukosis(EBL) is chronic disease caused by bovine leukemia virus(BLV), retroviridae. The characteristic feature of this disease is proliferation of lymphocytes in circulating blood or lymphoid tissues. Because EBL concern lymphocytes, immunological disorder or alteration in the lymphocyte subpopulation is suggested. In this study, we investigated the changes of the lymphocyte subpopulation in the circulating blood of Korean native cattle infected with bovine leukemia virus. (omitted)

• Korean Journal of Veterinary Service
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• v.30 no.1
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• pp.95-102
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• 2007

The purpose of this study was to investigate the seroprevalence of infection with the production-limiting diseases in dairy cattle in Jeonbuk-Iksan area. The blood samples were collected from 260 dairy cows in 52 herds, and examined. The antibody rates against N caninum, M paratuberculosis, and bovine leukemia virus were 34.6%, 13.5% and 89.6%, respectively. All samples for bovine brucellosis were negative.

• Korean Journal of Veterinary Service
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• v.30 no.1
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• pp.67-75
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• 2007

Bovine leukosis is one of the important diseases in Korea because of economic losses, and this study was conducted to provide basic information for the control of the disease. A total of 2,104 sera were obtained from 491 farms and examined by commercial kit. In the seroprevalence of farms and heads, 71 farms out of 491 were seropositive (14.5%) and 119 heads were positive (5.7%) out of 2,104. In the areal distribution of seropositiveness, Soseong-myeon showed the highest rate (39.5%, 15/38 farms)and Yeongwon-myeon was the lowest (2.6%, 1/38 farms). By age, positive rate in the below of 1 year old cattle was much less than that in the over of 1 year old, namely, the former was 1.9% (3/161 farms) and the latter 20.6% (68/330 farms). According to the farm size, there was no significant difference among the size. However, the highest rate was shown in the farms having 50-99 heads, 23.2% (13/56 farms).