Detection Of Bovine Leukemia Virus Research Articles

Use of two monoclonal antibodies in an ELISA test for the detection of antibodies to bovine leukaemia virus envelope protein gp51

A competition ELISA technique involving two monoclonal anti-gp51 antibodies has been developed for the detection of bovine leukaemia virus (BLV) antibodies. Precoated gp51 antigen-microtitre plates were obtained by incubation of plastic adsorbed monoclonal antibody with a non-purified BLV preparation. Samples to be tested were incubated in the wells of the gp51-coated plates; the presence of anti-gp51 antibodies was indicated by competition for antigen binding with an enzyme linked monoclonal antibody directed to an important epitope on gp51. This test is as sensitive as a routinely used indirect ELISA test; it is highly specific, reliable and easy to perform.

An investigation for seasonal trends in bovine leukemia virus infection

Monthly incidence rates for the detection of bovine leukemia virus (BLV) infection were calculated for a 15-month period for cattle over 12 months of age in a 200-cow dairy herd. Detection of BLV infection was based on the presence of persisting antibodies as measured by agar-gel immunodiffusion using the glycoprotein-51 antigen. A non-parametric procedure was used to examine 6-month trends in cumulative monthly incidence rates. Over the 15-month study, 25 heifers were detected as becoming infected with BLV after 12 months of age. No differences were found between the 12 monthly incidence rates ( p = 0.77). Cumulative incidence rates between June and September (the fly season) were not higher than those for any other 6-month period ( p = 0.29). Similarly, there was no evidence that BLV infection was transmitted during artificial insemination ( p = 0.18) or during routine vaccination procedures ( p = 1.0). Cumulative rates for a period corresponding to exposure of heifers to the dry herd were excessively high ( p = 0.01). These findings suggest that transmission of BLV infection in the cattle studied was associated with close physical contact between susceptible and infected cattle, and not with biting flies, artificial insemination, or vaccination procedures.

Use of monoclonal antibody in an ELISA test for the detection of antibodies to bovine leukaemia virus

A variant of the ELISA technique, involving a monoclonal anti-gp51 antibody yields a highly sensitive method for the detection of bovine leukaemia virus (BLV) antibodies. The gp51 antigencoated microtitre plates are obtained by incubation of plastic-adsorbed monoclonal antibodies with a non-purified mixture of BLV antigens. Sera to be tested are incubated in the wells of the gp51-coated plates and bound antibodies are revealed by an enzyme-linked antibovine immunoglobulin reagent. This test is as sensitive as liquid phase radioimmunoassay using the same gp51 antigen and thus appears as a highly sensitive, practical, rapid and cheap method for the detection of BLV antibodies.

Evaluation of syncytium assay for bovine leukemia virus.

As a new method for the detection of bovine leukemia virus (BLV) infection, syncytium assay was evaluated with lymphocytes from infected cattle and sheep. Only when lymphocytes from cattle with enzootic bovine leukosis and from sheep experimentally infected with BLV were used, syncytium formation was induced among indicator cells. A direct proportional dose response was presented by the number of inoculated lymphocytes from BLV-infected cattle to the number of syncytia formed. Treatment of lymphocytes from cattle with an adult form of lymphosarcoma with anti-BLV serum could inhibit the syncytium formation, but neither antiserum against bovine syncytial virus nor the sera from cattle with sporadic form of lymphosarcoma could inhibit. These results indicate the specificity and the usefulness of this assay for the detection of BLV infection.

Immunological nature of the inhibition of BLV-induced early polykaryocytosis by bovine sera.

A quantitative in vitro assay (EPI) was developed for the serological detection of bovine leukemia virus (BLV) infection in cattle. Positive sera inhibit early polykaryocytosis (EP) induced by BLV. We report herein experiments which demonstrate that BLV-induced antibodies are responsible for this inhibition. Serum fractionation by gel filtration and affinity chromatography indicate that EP-inhibiting activity is mediated only by immunoglobulins of the IgG class. Furthermore, on the basis of their ion-exchange chromatographic behaviour, these antibodies were classified as IgG1. We also ruled out the participation in the EP inhibition reaction of the other compounds such as polypeptides, including serum complement and interferon or DNA and RNA. These results demonstrate that EP inhibition by bovine sera is specific to BLV-induced antibodies.

A microculture syncytia assay for bovine leukemia virus

A microculture syncytia assay for the detection of bovine leukemia virus (BLV) has been described and compared with the conventional macroculture assay. The microculture assay required fewer indicator cells, was as sensitive as the macroculture assay and provided a reproducible test for the detection and titration of BLV.

Use of glycoprotein antigen in the immunodiffusion test for bovine leukemia virus antibodies

The agar gel immunodiffusion (AGID) test for detection of bovine leukemia virus (BLV) antibody was modified by substitution of glycoprotein antigen for p 24, the etherstable, internal viral antigen used in earlier investigations. This modified AGID test was compared with a complement fixation (CF) test that had shown superior sensitivity to the first AGID procedure. Sera from 263 cattle in commercial dairy herds were tested. The glycoprotein AGID test detected BLV antibodies in 171 sera, but the CF test detected only 134. In monthly examinations of sera from animals in a BLV experimental herd, the AGID test consistently detected more infected cattle. After experimental or natural infection, 14 of 19 cattle seroconverted to both the AGID and CF tests the same month. When antibodies were detected by only one test, it was usually the AGID test. Colostral antibodies in 2 calves from BLV-infected dams were detected longer by the AGID test than by the CF. These results show that the glycoprotein AGID test is more sensitive than the CF test for detection of BLV antibodies in cattle sera. The AGID test also offers distinct advantages in its simplicity and specificity and promises to be a useful tool for the development of BLV control and eradication programs.

Detection of Bovine Leukemia Virus in B-Lymphocytes by the Syncytia Induction Assay 2

Bovine peripheral blood lymphocytes (PBL's) from 3 cows and 1 steer infected with bovine leukemia virus (BLV) were separated by fractionation through nylon wool columns into nylon-adherent and nonadherent cell populations. Nylon-adherent cells were enriched in B-lymphocytes, as determined by the presence of surface membrane immunoglobulins (slg), whereas nylon-nonadherent cells or "non-B-lymphocytes" contained few slg-bearing cells. PBL's and separated B- and non-B-lymphocyte populations were assayed for the presence of BLV by the induction of syncytia in bovine embryonic spleen cells. PBL's and B-lymphocyte populations both produced many syncytia, whereas non-B-lymphocytes yielded few or no syncytia. The specificity of syncytia formation by anti-BLV serum. PBL's from 2 control animals were negative for syncytia induction. This study presents further evidence that B-lymphocytes are the target cells for BLV infection.