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1.
Lymphocytes from sheep experimentally infected with bovine leukosis virus (BLV) and from non-infected normal sheep were examined for the presence of surface Ig by an immunofluorescence test. Surface Ig-bearing lymphocytes in blood from BLV-infected sheep increased when lymphocyte counts of blood were elevated in comparison with normal animals. The mitogen stimulation of cultured lymphocytes from BLV-infected sheep and from non-infected normal sheep was determined by measuring 3H-thymidine incorporation. Peripheral blood lymphocytes (PBL) from BLV-infected leukemic sheep with elevated PBL counts responded poorly to phytohemagglutinin M and concanavalin A but responded well to lipopolysaccharide compared with lymphocytes from uninfected animals. In BLV-infected preleukemic sheep with low PBL counts, stimulation indices of mitogen responses of lymphocytes with phytohemagglutinin M, concanavalin A, and pokeweed mitogen were low compared with those of lymphocytes from uninfected animals. The results indicated that B cells were affected by BLV infection in sheep as suggested by the increased number of surface Ig-bearing lymphocytes and that significant alteration of mitogen stimulation of lymphocytes occured in sheep with BLV infection.  相似文献   

2.
This study was designed to determine the relative infectivity of lymphocytes and secretions from BLV-infected cattle with and without persistent lymphocytosis (BLV+PL+ and BLV+PL-). Ninety-seven sheep of mixed sex and age were assembled into 21 experimental groups. The recipient sheep were inoculated intravenously with serial dilutions of whole blood, saliva or nasal secretions from BLV+PL+ and BLV+PL- donor cows. Between 200 to 20,000 cells from single and mixed BLV+PL+ or single and mixed BLV+PL- donor cattle were used for inoculation. A very small number of BLV-infected lymphocytes (200 cells) was sufficient to induce BLV infection in sheep inoculated with diluted whole blood from BLV+PL+ cattle. The inoculation of whole blood (containing up to 20,000 lymphocyte cells) from BLV+PL- cattle did not induce BLV infection in recipient sheep. Saliva and nasal secretions also failed to bring about BLV transmission.  相似文献   

3.
Monoclonal antibodies and microfluorimetry were used to determine the absolute number of B and T lymphocytes in the blood of bovine leukemia virus (BLV)-infected cows. The blood lymphocyte populations from BLV-infected cows were significantly higher than those from BLV-negative cows. The increase in the lymphocyte population in 3 BLV-infected nonlymphocytotic cows was attributed to a significant increase in the number of T lymphocytes; in 3 BLV-infected persistently lymphocytotic cows, the increase was attributed to a significant increase in the number of B and T lymphocytes. One persistently lymphocytotic cow had a high lymphocyte count, and lymphocytes from this cow contained cells that appeared to stain with markers specific for bovine B and T lymphocytes. We concluded that infection of cattle with the B-cell lymphotropic retrovirus, BLV, not only affected B cells, but also T cells.  相似文献   

4.
Lectins, polyclonal antibodies and monoclonal antibodies (MAbs) were evaluated as markers for bovine lymphocytes obtained from healthy animals and from cattle infected with bovine leukemia virus (BLV). In the blood from healthy cattle the proportion of cells identified as T lymphocytes with the lectin Helix pomatia (HP) (67.8 +/- 6.2%) using the indirect immunofluorescence technique was similar to the proportion of cells identified by the MAbs P5 (66.1 +/- 3.8%) and BLT-1 (59.8 +/- 7.1%). The proportion of B cells in blood from healthy animals identified with a polyclonal antibody to bovine IgM (18.0%) was similar to that identified with a MAb to bovine IgM (16.2%). However, greater variation between individual values was detected with the MAb (SD = 8.2) than with the polyclonal antibody (SD = 4.0). In the blood from BLV-infected cattle with persistent lymphocytosis, both the polyclonal and the MAb revealed a threefold increase of B cells. A proportion of the B cells had an increased amount of immunoglobulin molecules in their plasma membrane as indicated by flow cytometry. The proportion of T lymphocytes, identified by the MAb P5, was reduced to one-third of that in non-infected cattle. The indirect HP labelling gave inconsistent results and seems not to detect solely T lymphocytes among blood lymphocytes from BLV-infected cattle.  相似文献   

5.
Expression of L-selectin was determined by single- and two-colour immunofluorescence on granulocytes, peripheral blood mononuclear cells (PBMC) and blasts of bovine origin by means of a monoclonal antibody IVA94 which recognizes bovine L-selectin (CD62L). Cells were separated from peripheral blood of healthy cattle and colleagues infected with bovine leukaemia virus (BLV). BLV-infected animals comprised lymphocytotic and non-lymphocytotic cows. L-selectin was expressed on 90-98% of granulocytes in all tested animals. The percentage of PBMC expressing L-selectin was lower in cattle with persistent lymphocytosis than in non-lymphocytotic or BLV-free cattle, and inversely correlated with lymphocyte counts. The ratio of B lymphocytes stained for L-selectin was significantly decreased from 60.2 +/- 1.9% in BLV-free cattle to 43.8 +/- 3.6 and 22.5 +/- 5.7% in non-lymphocytotic and lymphocytotic cattle, respectively. B-lymphocytes stained for L-selectin exhibited about 50% reduction in L-selectin expression in BLV-infected cattle compared with BLV-free cattle, as judged by the mean fluorescence intensity (MFI). The percentage of L-selectin-positive PBMC not bearing surface immunoglobulin M (predominantly T lymphocytes) was comparable in BLV-free and BLV-infected cattle. However, L-selectin expression on T lymphocytes was reduced (about 50%) in BLV-infected cattle, as judged by the MFI. We suppose that BLV infection results in a decreased L-selectin expression on lymphocytes, and accordingly, it may contribute to deregulation of the host immune system.  相似文献   

6.
Peripheral blood lymphocytes (PBL) from cattle and sheep exhibited natural cytotoxicity on a fetal lamb kidney (FLK) cell line that was persistently infected with bovine leukemia virus (BLV) by 20-h 51Cr release assay. This cytotoxic activity was tested using PBL from normal cattle and sheep or BLV-infected animals. Although cytotoxic activity was also found in PBL from normal animals and from BLV-infected, but clinically healthy animals, the activity in PBL from animals with persistent lymphocytosis or leukemic animals was markedly decreased. The cytotoxic activity of PBL from 3 sheep sequentially tested before and during the disease was found to decrease gradually with the progress of the disease, and finally no cytotoxic activity was found at the time of death due to leukemia. These results suggest that the natural cytotoxic activity in PBL may have a role in immunosurveillance for progress of the tumor.  相似文献   

7.
Twelve sheep were experimentally infected with a phytohemagglutinin (PHA) treated short term culture of lymphocytes from a cow naturally infected with BLV at the PL stage. Five of 12 (42%) BLV infected sheep had histologically confirmed lymphosarcoma 10-16 months after infection. The PBL's were increased to leukemic levels 3-21 weeks before death due to lymphoblastic leukemia. Lymphocyte proliferation and appearance of immature lymphocytes and lymphoblastic cells in the blood were a characteristic feature of tumour development following inoculation with an Australian strain of BLV. In contrast to a number of previous studies the peripheral lymph nodes of all infected sheep were clinically normal throughout the experimental period but at death gross tumours were evident in the mesentric lymph nodes and the heart in all cases. All the other lymph nodes, liver, spleen, kidney and lung were histologically infiltrated with lymphoid tumour cells. Gross tumours were present in the abomasum (1 out of 5) in the urinary tract (2 out of 5) and in the uterus (1 out of 2). The majority of the tumour cells isolated from the various tissues were centroblastic demonstrating that the malignant leukemia in experimentally infected sheep was of a multicentric centroblastic type. The central nervous system was not involved in any case.  相似文献   

8.
Expression of L‐selectin was determined by single‐ and two‐colour immunofluorescence on granulocytes, peripheral blood mononuclear cells (PBMC) and blasts of bovine origin by means of a monoclonal antibody IVA94 which recognizes bovine L‐selectin (CD62L). Cells were separated from peripheral blood of healthy cattle and colleagues infected with bovine leukaemia virus (BLV). BLV‐infected animals comprised lymphocytotic and non‐lymphocytotic cows. L‐selectin was expressed on 90–98 % of granulocytes in all tested animals. The percentage of PBMC expressing L‐selectin was lower in cattle with persistent lymphocytosis than in non‐lymphocytotic or BLV‐free cattle, and inversely correlated with lymphocyte counts. The ratio of B lymphocytes stained for L‐selectin was significantly decreased from 60.2 ± 1.9 % in BLV‐free cattle to 43.8 ± 3.6 and 22.5 ± 5.7 % in non‐lymphocytotic and lymphocytotic cattle, respectively. B‐lymphocytes stained for L‐selectin exhibited about 50 % reduction in L‐selectin expression in BLV‐infected cattle compared with BLV‐free cattle, as judged by the mean fluorescence intensity (MFI). The percentage of L‐selectin‐positive PBMC not bearing surface immunoglobulin M (predominantly T lymphocytes) was comparable in BLV‐free and BLV‐infected cattle. However, L‐selectin expression on T lymphocytes was reduced (about 50 %) in BLV‐infected cattle, as judged by the MFI. We suppose that BLV infection results in a decreased L‐selectin expression on lymphocytes, and accordingly, it may contribute to deregulation of the host immune system.  相似文献   

9.
Ten 2- to 4-month-old rabbits were inoculated subcutaneously with bovine leukemia virus (BLV)-infected bovine or sheep cells. By 6 weeks after inoculation all ten rabbits had converted to BLV antibody-positive, and BLV or BLV antigen was detected in lymphocytes from most of the rabbits tested, although there were few antigen-producing cells. Three rabbits showed continuous respiratory symptoms after infection and one died with pneumonia. Humoral immune responses against mouse serum were significantly suppressed in BLV-infected rabbits compared with non-infected control rabbits. The lymphocyte blastogenesis response was also suppressed in BLV-infected rabbits. At the time of necropsy, six rabbits showed pulmonary lesions; however, none of the BLV-infected rabbits had tumors during an observation period of over 1 year.  相似文献   

10.
The BLV-induced leukemia--lymphosarcoma complex in sheep   总被引：3，自引：0，他引：3  
Sheep are highly susceptible to BLV infection and can be infected via several different means (routes). In all inoculated animals, specific anti-BLV antibodies can be demonstrated 1 to 3 months post-inoculation (p.i.). Between 10 and 13 months p.i., a moderate but persistent lymphocytosis (PL) may be detected in about 50% of the infected animals. This hematological disorder may be, but is not necessarily, associated with the development of a lymphosarcoma and can (might) be interpreted as a true lymphoid leukemia. According to findings revealed by immunolabelling and mitogen stimulation of peripheral blood lymphocytes, BLV-induced PL appears to be a B-cell disorder. Induced lymphosarcoma appears in about 40% of infected sheep during the 6 years p.i. It too is of B-lymphocyte lineage. In vitro studies demonstrate that BLV antigen is expressed exclusively in B-lymphocytes. Yet, BLV expression is greatly stimulated in whole lymphocyte culture by the addition of T-cell mitogen. This same phenomenon occurs when the supernatant of stimulated T-lymphocyte cultures is added to isolated BLV-infected B-lymphocytes. This observation supports the hypothesis that, as is the case with other retroviruses such as HIV, BLV is able to use the regular activation machinery of the immune system for its own replication and transmission. It seems, therefore, that the leukemia-lymphoma complex in sheep may serve as an accurate experimental model for the study of the biological properties of retroviruses.  相似文献   

11.
To examine the effect of recombinant bovine interferon-gamma (rbIFN-gamma) on cattle persistently infected with bovine leukemia virus (BLV), BLV-infected cattle were inoculated intraperitoneally with IFN-gamma. All cattle were febrile after inoculation with IFN-gamma and then recovered within 48 h. Flow cytometric analysis showed that the numbers of CD4+ and CD8+ T cells were decreased for 2-3 days and then their numbers were recovered. The number of gammadelta T cells increased after the fever. In contrast, the number of IgM+ lymphocytes remained low for about 1 week. Moreover, the numbers of syncytia produced by peripheral blood lymphocytes decreased and remained low compared to that before IFN-gamma administration. These results suggest that IFN-gamma induces the up-regulation of gammadelta T cells, decreases the number of IgM+ lymphocytes and suppresses the growth of BLV in BLV-infected cattle in vivo.  相似文献   

12.
Six sheep with lymphosarcoma induced by hypodermic inoculation of bovine leukemia virus (BLV) materials were examined to elucidate the relation between pathologic lesions and integration of BLV provirus in cellular DNAs. Antibodies to BLV gp-antigens had been detected since the 3rd week after the inoculation, and BLV was positive when checked 3 months later. Lymphosarcomas followed the leukemic phase in 4 sheep. The other 2 sheep showed initial lesions of lymphosarcoma and were aleukemic clinically. Five animals were killed by enthanasia and autopsied at 2.5 to 3.5 years postinoculation (pi) because of their diseased condition. One animal died 10 years pi following the 4th leukemic episode. Sarcomatous lesions were confirmed grossly and histologically, and the proliferating neoplastic cells were classified into lymphocytic, prolymphocytic, lymphoblastic and histiocytic types. Integration of BLV provirus in cellular DNAs of the peripheral blood lymphocytes (PBL) and neoplastic cells of sarcomatous lesions was examined by Southern blotting technique. BLV provirus was demonstrated in the PBL of all infected animals and in most of the sarcomatous lesions of the spleen, kidney and lymph nodes except 4 lymph nodes showing slight neoplastic infiltration. The results indicated that ovine lymphosarcoma could be caused by BLV and the cells carrying proviral information seemed to be disseminated and proliferate in the lesions.  相似文献   

13.
The migration of fluorescein isothiocyanate labelled lymphocytes through the tracheobronchial mucosa has been studied in cattle. Following intratracheal inoculation of labelled non-infected autologous lymphocytes and bovine leukosis virus (BLV) infected heterologous (presumed allogeneic) lymphocytes, the labelled lymphocytes appeared in the blood circulation between 4 and 7 days post inoculation. Following intravenous inoculation of labelled autologous lymphocytes, the cells could be detected in the circulation for 10 days post inoculation whereas BLV infected and non-infected heterologous lymphocytes could be detected for only 2 days. The migration of BLV-infected heterologous lymphocytes through the tracheobronchial mucosa caused a delay in the appearance of labelled lymphocytes in the circulation and a corresponding delay in the appearance of BLV antibodies. Comparison was made of the effect of two different routes of inoculation, subcutaneous and intratracheal on the incubation period as indicated by the detection of antibody. Subcutaneous inoculation of 1 X 10(4), 5 X 10(3), 1 X 10(3) of lymphocytes from a BLV infected cow caused seroconversion whereas 5 X 10(2) cells did not. Intratracheal inoculation of 5 X 10(3) cells caused sero-conversion. One animal did not develop BLV antibody until 30 weeks after inoculation although BLV could be isolated from the blood at 24 and 26 weeks post inoculation.  相似文献   

14.
The humoral and cellular immunological reactivity of sheep were studied throughout the first 32 weeks following experimental infection with bovine leukemia virus (BLV). Seroconversion of BLV-inoculated sheep occurred within 4 weeks, but infection was not transmitted to contact control sheep. Despite the persistence of the viral infection, no differences were demonstrated in leukograms, serum IgG concentrations, humoral response to immunization with an irrelevant antigen (rabbit red blood cells), phytomitogen (Concanavalin A and Pokeweek mitogen)-induced lymphocyte blastogenesis, or chemical (1-chloro, 2-4 dinitrobenzene) skin contact hypersensitivity, between BLV-infected and uninfected contact control sheep. These results demonstrate the absence of a nonspecific immunosuppressive effect of BLV and further negate the influence of a generalized immunological deficit on the development of clinical disease in BLV-infected animals.  相似文献   

15.
The single intradermal comparative test was used with both avian and bovine tuberculin. Three cattle infected with bovine leukosis virus (BLV) were used as a source of infection. BLV-positive and susceptible animals were tuberculin tested alternately. Fifteen susceptible calves and 15 susceptible sheep were tested. A further three calves and three sheep were used as controls; the needles of the tuberculin syringes were deliberately contaminated with blood from the BLV-infected cattle, before being used in the test. Whereas all three calves and the three sheep inoculated intradermally with contaminated needles developed BLV infections, all of the other 30 animals have remained serologically negative to BLV for 10 months. Transmission of BLV with needles contaminated with BLV-infected blood was prevented by wiping the needles with absorbent cotton wool.  相似文献   

16.
This report describes a modified syncytia infectivity assay (SIA) for the direct detection of bovine leukemia virus (BLV) in blood lymphocytes of cattle, using transformed feline (CC81) cells as the indicator system. The data show that the syncytia present in cultures of CC81 cells inoculated with BLV-infected cells are specific and arise through a mechanism similar to that responsible for the phenomenon of "late" polykaryocytosis described in other virus systems. The susceptibility of the CC81 cells to the syncytia-inducing effect of BLV-infected cells is comparable with that of early passages of bovine embryonic spleen cells, which were previously used as the indicator system in the SIA. Unlike the bovine embryonic spleen cells, CC81 cells retain their susceptibility to syncytia induction for long periods of cultivation. Furthermore, the syncytia induced in the CC81 cultures are larger and easier to identify. Thus, the CC81 cells can be used advantageously as the indicator system when the SIA is applied to the detection of BLV-infected lymphocytes. The results of the SIA for the detection of infective BLV agreed closely with those of the radioimmunoassay for the detection of BLV antibodies in randomly examined cattle. On the other hand, many cattle in early stages of infection were positive in the radioimmunoassay several months before they reacted in the SIA. The detection of BLV in blood lymphocytes provides a useful method for the diagnosis of BLV infection in cattle when serologic tests cannot be used, eg, calves that may have passively acquired maternal antibodies and cattle given BLV vaccines.  相似文献   

17.
Pairs of newborn calves were exposed to bovine leukemia virus (BLV) when they were given their 1st colostrum feeding. Calves that were given 10(6) BLV-infected lymphocytes in colostrum free of BLV-specific antibody became infected. Calves that were fed 10(7), 10(8), or 10(9) infected lymphocytes in colostrum that contained BLV-specific antibody did not become infected. One of 2 calves inoculated intradermally with 250,000 infected lymphocytes was protected by colostral antibody, but the other was not. Colostral antibody titers in the unprotected calf decreased normally until the calf was 4 months old and then increased markedly; this pattern indicates that the presence of colostral antibody may have prolonged the latent period of the BLV infection.  相似文献   

18.
Immunological control of bovine leukemia virus (BLV)-infection has been reported as dependent on the expression balance of types 1 and 2 cytokines. In this report, mRNA expression of interferon (IFN)-gamma and interleukin (IL)-2 (type 1 cytokines), and of IL-4 and IL-10 (type 2 cytokines) were evaluated in concanavalin A-stimulated peripheral blood mononuclear cells (PBMC) from BLV-infected sheep. Despite the same dose of BLV-infection, the extent of viral propagation was markedly different between eight individual sheep by 12 weeks post infection. The virus did not propagate well in three sheep, which showed augmented mRNA expression of IFN-gamma, a strong indicator of cell-mediated immunity, immediately after BLV-infection. Among the other five sheep having more than 2% of BLV-infected cells among PBMC at 12 weeks post infection, four sheep developed B-cell leukemia or lymphoma within 2 years after infection. These observations indicate IFN-gamma expression may play an important role in the protective mechanism against BLV propagation at the early phase of the infection.  相似文献   

19.
Specific tumor-associated antigen (TAA) was detected on enzootic bovine leukosis (EBL) cells by monoclonal antibodies against TAA. One of the monoclonal antibodies, c143, reacted with all EBL tumor cells tested but not with bovine leukemia virus (BLV) antigens. c143 reacted slightly with bovine fetal thymus and mitogen-stimulated lymphocytes from BLV-free cows but not with normal bovine lymphoid cells. TAA may be a good tumor marker of EBL tumor cells. We sacrificed eight TAA-positive but clinically normal animals and examined them in order to elucidate whether or not they had gross or histological tumors. At necropsy, four animals had tumors macroscopically. Three animals had no tumors histologically but had initial lesions showing follicular hyperplasia and the TAA on affected lymph nodes. The one remaining showed medullary hyperplasia in the spleen but there were no findings of tumors. Thus, c143 is a useful tool not only for diagnosing EBL, but also for screening of BLV-infected cattle with potential to develop tumors in the future.  相似文献   

20.
Bovine leukosis virus (BLV) was transmitted to sheep in a simulated mechanical transmission experiment, using the following species of mosquitoes; Anopheles freeborni, A stephensi, A quadrimaculatus, and A albimanus. Mosquitoes were fed on blood taken from a BLV-infected cow with persistent lymphocytosis. Mouthparts and heads of mosquitoes were removed immediately after feeding, placed in RPMI 1640 medium, and inoculated subcutaneously into sheep. Nine sheep were inoculated with mouthparts and heads from 37 to 122 mosquitoes. Infection was determined serologically. Three monthly serum samples were collected from the sheep and were tested for the presence of antibodies to BLV, using the agar-gel immunodiffusion (AGID) test. Sera that were negative by AGID at 3 months were tested by radioimmunoassay. Results from radioimmunoassay agreed with those obtained by AGID. Four of the 9 sheep developed antibody to BLV. Sheep that seroconverted were inoculated with mouthparts and heads from as few as 54 mosquitoes.  相似文献   

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