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Biomedical subjects

M Mammerickx

Publications and source records attributed to M Mammerickx.

At least 37 records · Page 2Linked to original sources
PubMed1990

Development of a specific serological test and an efficient subunit vaccine to control bovine leukemia virus infection.

Study of the antigenic structure of the Bovine Leukemia Virus (BLV) envelope glycoprotein gp51 with a panel of mouse monoclonal antibodies (MAbs) has allowed the identification of biologically important determinants directly involved in the infectivity of BLV. Considering the various facts reported in this paper, it follows that diagnostic and vaccination procedures that make use of gp51 in a native configuration constitute a prerequisite for the design of an efficient BLV eradication program. To improve the efficacy of a serological detection test, MAbs have been selected as reagents of choice to develop a competition enzyme-linked immunosorbent assay (cELISA). Recombinant vaccinia virus expressing gp51 and gp30 was indicated as a very promising protective vaccine against BLV infection.

Amino Acid Sequence↗
PubMed1989

Bovine leukemia virus (BLV)-infected B-cells express a marker similar to the CD5 T cell marker.

In the course of generating monoclonal antibodies to bovine thymus-dependent differentiation antigens, we were able to characterize an antibody, termed 8C11, that detects an antigen shared by a majority of thymocytes and peripheral T cells (in blood and thymus-dependent area of spleen and lymph-nodes), but undetectable on normal B cells. However, this antibody was reactive with B cells from cows infected with bovine leukemia virus (BLV). These BLV-infected B cells were found to express simultaneously high concentrations of both surface IgM and 8C11-detected antigen. The antigen recognized by this antibody was shown to be a 67.5 kDa molecule. Because similar findings have been made on mouse myelomas and on human chronic leukemia cells, where this antigen was considered to be the equivalent of mouse Ly-1 antigen and human Leu-1 or CD5 antigen, the T cell antigen detected on BLV-infected cells could be the bovine counterpart of the CD5 antigen. By another way, it has been found that the CD5 T cell antigen is also present on a minor subpopulation of B cells in the spleen but not in the blood. We suggest that in the bovine a similar B cell subpopulation should be the BLV target and expand as a consequence of viral insertion, leading to the persistent lymphocytosis observed on BLV-infected animals.

Animals↗
PubMed1989

Antigenic variants of bovine leukemia virus (BLV) are defined by amino acid substitutions in the NH2 part of the envelope glycoprotein gp51.

Previous studies with monoclonal antibodies of the antigenic structure of bovine leukemia virus (BLV) envelope glycoprotein (gp51) have identified three epitopes (F, G, H) directly involved in the infectivity of BLV, F, G, and H lost their reactivity with the respective monoclonal antibodies after treatment with a reducing agent, indicating that these epitopes were conformational. Sequence comparisons between BLV mutants and differential reactivities of urokinase or proteinase K gp51 fragments with monoclonal antibodies indicated that the NH2 moiety of the env protein harbored the three architectural determinants F, G, and H. ELISA tests demonstrated that anti-F, -G, and -H monoclonal antibodies were maximally reactive toward intact virions whereas they showed much poorer affinities for their respective epitopes when presented on a purified protein. Accordingly, an efficient vaccine against BLV infection will include at least the identified gp51 region presented in its native architectural configuration.

Amino Acid Sequence↗
PubMed1989

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.

Animals↗
PubMed1988

Detection of B and T cells, with lectins or antibodies, in healthy and bovine leukemia virus-infected cattle.

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.

Animals↗
PubMed1988

Bovine leukaemia: facts and hypotheses derived from the study of an infectious cancer.

Bovine leukaemia virus (BLV) is the etiological agent of chronic lymphatic leukaemia/lymphoma in cows, sheep and goats. Infection without neoplastic transformation was also obtained in pigs, rhesus monkeys, chimpanzees, rabbits and observed in capybaras and water-buffaloes. Structurally and functionally, BLV is a relative of human T lymphotropic viruses 1 and 2 (HTLV-I and HTLV-II) In humans, HTLV-I induces a T-cell leukaemia and its type 2 counterpart has been found in dermatopathic lymphadenopathy, hairy T-cell leukaemia and prolymphocytic leukaemia cases. At variance with HTLV-I, BLV has not been associated with neurological diseases of the degenerative type. Bovine leukaemia virus, HTLV-I and HTLV-II show clearcut sequence homologies. The pathology of the BLV-induced disease, most notably the absence of chronic viraemia, a long latency period and lack of preferred proviral integration sites in tumours, is similar to that of adult T-cell leukaemia/lymphoma induced by HTLV-I. The most striking feature of these three naturally transmitted leukaemia viruses is the X region located between the env gene and the long terminal repeat (LTR) sequence. The X region contains several overlapping long open reading frames. One of them, designated XBL-I, encodes a trans-activator function capable of increasing the level of gene expression directed by BLV-LTR and most probably is involved in "genetic instability" of BLV-infected cells of the B cell lineage. The "genetic instability" renders the infected cell susceptible to move, along a number of stages, towards full malignancy. Little is known about these events and their causes; we present some theoretical possibilities. Bovine leukaemia virus infection has a worldwide distribution. In temperate climates, the virus spreads mostly via iatrogenic transfer of infected lymphocytes. In warm climates and in areas heavily populated by haematophagous insects, there are indications of insect-borne propagation of the virus.

Animals↗
PubMed1988

Bovine leukemia: facts and hypotheses derived from the study of an infectious cancer.

Bovine leukemia virus is the etiological agent of a chronic lymphatic leukemia/lymphoma in cows, sheep, and goats. Infection without neoplastic transformation also was obtained in pigs, rhesus monkeys, chimpanzees, and rabbits, and was observed in capybaras and water buffaloes. Structurally and functionally, BLV is a relative of the human T lymphotropic viruses (HTLV-I and HTLV-II). HTLV-I induces in humans a T cell leukemia, and its type II counterpart has been found in dermatopathic lymphadenopathy, hairy T cell leukemia and prolymphocytic leukemia cases. At variance with HTLV-I, BLV has not been associated with neurological diseases of the degenerative type. BLV, HTLV-I, and HTLV-II show clearcut sequence homologies. The pathology of the BLV-induced disease, most notably, the absence of chronic viremia, a long latency period, and a lack of preferred proviral integration sites in tumors, is similar to that of adult T cell leukemia/lymphoma induced by HTLV-I. The most striking feature of the three naturally transmitted leukemia viruses is the X region located between the env gene and the LTR sequence. The X region contains several overlapping long open reading frames. One of them designated XBL-I encodes a trans-activator function capable of increasing the level of gene expression directed by BLV-LTR and most probably involved in "genetic instability" of BLV-infected cells of the B cell lineage. The genetic instability puts the cell into a context of fragility and ready to move along a number of stages towards full malignancy. Little is known about these events and their causes; we have presented some theoretical possibilities. BLV infection has a worldwide distribution. In temperate climates the virus spreads mostly via iatrogenic transfer of infected lymphocytes. In warm climates and in areas heavily populated by hematophageous insects, there are indications of insect-born propagation of the virus.

Animals↗
PubMed1988

Even transcriptionally competent proviruses are silent in bovine leukemia virus-induced sheep tumor cells.

To investigate the role of proviral integration and expression in cellular transformation induced by bovine leukemia virus (BLV), three BLV-induced tumors harboring a single proviral copy were selected upon restriction and hybridization analysis. Tumors 344 and 395 were shown to contain a full-size proviral copy, whereas in tumor 1345 the provirus appeared to be heavily deleted. RNA gel blot hybridization with an antisense RNA probe showed no transcription of the viral sequences in the fresh tumors or in sheep tumor cells growing in vitro. The proviruses were cloned and transfected in mammalian cell lines. Transient-expression experiments revealed that the complete proviruses were still able to express the trans-activating protein (Tat) as well as structural proteins, demonstrating that the nonexpression of a provirus in a tumor cell does not necessarily imply a structural alteration of the viral information. In contrast, sequence analysis of the provirus with a large deletion and transient-expression assays proved that this truncated provirus, isolated from a tumor, was unable to code for viral proteins. These data indicate that expression of viral genes, including tat, is not required for the maintenance of the transformed state.

Animals↗
PubMed1988

Experimental transmission of enzootic bovine leukosis to sheep: latency period of the tumoral disease.

In the field of viral oncogenesis the latency period is the interval between detectable establishment of infection and appearance of a tumor. Between 1969 and 1985, a total of 60 sheep died with lymphosarcoma. They were inoculated with BLV-positive blood from various donor cows, by various routes, at various ages, etc. A statistical analysis was performed trying to find a correlation between the length of the latency period and, on the other hand, one or more factors, such as sex, family lineage, identity of the dam, age at inoculation, route of inoculation, or origin of the inoculum. None of the above mentioned parameters has a significant effect on the length of the latency period. In two series of sheep inoculated with decreasing number of lymphocytes from BLV-positive donor cows, hematological disorders and tumors appeared at first in recipient animals inoculated with the higher doses of infectious blood. Thus, the inoculated dose has an effect upon the length of the latency period; the higher the dose inoculated, the shorter the latency period. This finding suggests an explanation to the natural occurrence of multiple case herds as opposed to no-tumor case herds. A multiple case herd fulfills two conditions: the presence of a good donor and an efficient route of transmission allowing the transfer to the recipient of the optimal amount of infected blood.

Animals↗
PubMed1987

Experimental transmission of enzootic bovine leukosis to cattle, sheep and goats: infectious doses of blood and incubation period of the disease.

A group of 49 BLV-free recipient animals (24 cattle, 15 sheep and 10 goats) were inoculated intradermally with serial dilutions of blood collected on two BLV-positive donor cows. One donor had a high lymphocytosis and high antibody titers to gpBLV antigens; these two parameters were low for the second donor. The number of lymphocytes which induced BLV infection in recipient animals varied widely with the donor. The high infectivity of a donor seemed to be correlated with high lymphocytosis and high antibody titers to gpBLV antigens. Identification and removal of infectious animals would reduce or stop the spread of the infection in a herd, and could be used in the strategy to eradicate the disease. A given inoculum can be infectious in sheep and, at the same time, harmless in cattle. The incubation periods, apparently shorter in sheep, were generally in the range from 2 to 5 weeks for the three species, and exceptionally above.

Animals↗
PubMed1987

Bovine leukaemia: facts and hypotheses derived from the study of an infectious cancer.

Bovine leukaemia virus (BLV) is the aetiological agent of a chronic lymphatic leukaemia/lymphoma in cows, sheep and goats. Infection without neoplastic transformation has also been demonstrated in pigs, rhesus monkeys, chimpanzees and rabbits and observed in capybaras and water buffaloes. Structurally and functionally, BLV is a relative of human T lymphotropic viruses 1 and 2 (HTLV-I and HTLV-II) since all three viruses show clear-cut sequence homologies. The pathology of the BLV-induced disease, most notably the absence of chronic viraemia, a long latency period and lack of preferred proviral integration sites in tumours, is similar to that of adult T-cell leukaemia/lymphoma induced by HTLV-I. The most striking feature of the three naturally transmitted leukaemia viruses is the X region located between the env gene and the long terminal repeat (LTR) sequence. The X region contains several overlapping long open reading frames, one of which, designated XBL-1, encodes a trans-activator function capable of increasing the level of gene expression directed by BLV-LTR and is most probably involved in genetic instability of BLV-infected cells of the B-cell lineage. The 'genetic instability' may put the cell into a state of fragility, ready to move along a number of stages towards full malignancy. Little is known about these events and their causes and we present some theoretical possibilities. BLV infection has a worldwide distribution. In temperate climates the virus spreads mostly through iatrogenic transfer of infected lymphocytes. In warm climates and in areas heavily populated by haematophagous insects, there are indications of insect-borne propagation of the virus.

Animals↗
PubMed1986

[Experimental inoculation of bovine herpesvirus 4 (strain LVR 140) in pregnant and nonpregnant cows].

Ten cows (5 pregnant and 5 non pregnant) were inoculated with a BHV 4 (Bovine Herpes Virus 4) strain LVR 140. The infection caused metritis symptoms, but only after parturition and even if the calving occurred several weeks after the inoculation. The metritis was accompanied by leucopenia. The virus was reisolated from the lochia and the lymph nodes, in some cases several weeks after parturition. A number of unexplained mortalities was observed during the experiment. The evolution of antibodies detected by the indirect immunofluorescence test (IIF) showed two levels: the first after inoculation and the second after parturition.

Animals↗
PubMed1985

The diagnosis of enzootic bovine leukosis.

This paper reviews the clinical and virological diagnostic procedures for enzootic bovine leukosis (EBL). The clinical diagnosis must be always confirmed by a specific laboratory test for Bovine Leukaemia Virus (BLV). Many virological tests were proposed. The sensitivity of all the diagnostic methods is sufficient to do an early detection of a BLV infection on an individual base. Advantages of the highly sensitive methods like RIA and ELISA appear when the samples to be tested have naturally very low antibody titers (individual milk, bulk milk, pooled sera).

Animals↗