Differentiation of an epiperiosteal sheath in avian hyperostosis induced by myeloblastosis associated virus MAV-2 (0).

If myeloblastosis associated virus MAV-2(0) is injected in chick embryos, it causes a severe, irreversible and generalized hyperostosis which subsequently follows a chronic course. An epiperiosteal sheath forms at the site of the lesion, whose development follows that of the hyperostosis. The sheath contains not only cell infiltrates, blood vessels and myoblasts, but also highly specialized cells such as Pacinian corpuscles. The structural lesions are absolutely different from these described in human, mammal or avian spontaneous or induced osteopetrosis. Our initial description of the "hyperostosis" is confirmed by observation of this sheath surrounding the pathological bone: it is a monodermic, mesenchymal, pluritissular tumor. The role of the virus is discussed: it probably acts early, when mesenchymal stem cells differentiate.

Effect of a preliminary infection of ducks with EDS-76 virus on the Derzsy's disease pathology.

The aim of this work was to investigate the role of a non pathogenic adenovirus (EDS-76, strain A-127), frequently isolated from ducklings on the infection by a pathogen agent (such as the parvovirus responsible for Derzsy's disease, DDV). Three groups of ducklings were respectively infected with A-127 alone, at day old, DDV alone at day 10th, A-127 at day old plus DDV at day 10th. The infected groups and a control one were raised under similar conditions. Pathological signs were observed and body weights recorded. Sera were collected weekly and analysed for DDV and A-127 antibodies. In addition, in vitro assays of the multiplication of these viruses and studies on cytopathic effects on duck embryo fibroblasts were conducted. The humoral response did not appear to be influenced by dual infection. No differences in cytopathogenic effects were detected in vitro between single and dual infection. On the other hand, in ducklings, dual infection increased the mortality rate and depressed the body weight gain, as compared to infection with either virus alone. The drastic effect on the body weight gain of the EDS-76 virus in the presence of DDV clearly shows a synergic role of this virus on the course of Derzsy's disease.

Chicken thymocyte-specific antigens identified by monoclonal antibodies: characterization and distribution in normal tissues and in tumoral tissues from Marek's disease chicken.

Monoclonal antibodies (MAbs) were obtained against purified thymocyte membrane extracts. Five MAbs TA3, TB1, TB6 (IgG1), TC4, and TA1 (IgG2a), were tested by immunofluorescence and by immunoperoxidase tests against normal cells from different organs, Marek's disease (MD) cell lines, and MD tumoral cells from chickens. Three of them, TA3, TB1, and TB6, reacted exclusively with lymphoid cells in both cortical and medullary areas of the thymus and with less than 8% bursa cells. They identified a protein of apparently 40 kD. The other two revealed antigenic determinants on most medullar thymocytes and some cortical thymocytes, and on some splenic and peripheral blood lymphocytes. They were positive with MD cell lines and cells deriving from MD tumors. TC4 and TA1 detected molecular masses of about 110 kD and 16 kD, respectively. No MAbs reacted with erythrocytes, bone marrow, liver, brain, and skin cells. Not all of the tested cells were stained after contact with an anti-chicken immunoglobulin serum. In this paper, we determine a specific antigen restricted to T cells from thymus and different markers belonging to the mature T cells. The latter are also present on MD cell lines and MD tumoral cells.

Protein concentrations and immunosuppressive properties of serum in chickens experimentally infected with avian tumor viruses.

Sera from chickens affected by Marek's disease or developing Rous sarcoma were investigated. There were changes in the protein fractions, and the amount of alpha and beta fractions was consistently increased. At the same time, immunosuppressive factors were found to inhibit the number of plaque-forming cells in the spleen of mice immunized with sheep red blood cells.

[Involvement of bone tissue in chicken infected with the myeloblastic MAV 2-0 virus. Generalized cortical hyperostosis]. / Atteinte du tissu osseux des Poulets infectés par le virus myéloblastique MAV 2-0. Hyperostose corticale généralisée.

An affection of osseous tissue appears in chicken have been injected at the embryonic state with retrovirus myeloblastic MAV 2-0 in solution. The structural lesions are different from these examined in human or murine osteopetrosis, considered to be an general cortical hyperostosis.

[The periosteum in experimental avian hyperostosis induced by MAV 2-0 myeloblastosis virus. Differential diagnosis from osteopetrosis]. / Le périoste dans l'hyperostose aviaire expérimentale induite par le virus myéloblastique mav 2-0. Diagnostic différentiel de l'ostéopétrose.

Diaphyseal tibial bones of 11-14-17 th day-old hatched chicks infected with retrovirus myeloblastic MAV 2-0 were examined by conventional optical microscopy. The characteristic lesion is osteoblastic hyperplasia with the development of spongious bone. The new formed bone contains abnormal chondroid tissue. The relation between osseous and cartilaginous tissues in this experimental model is discussed. As connective tissue took part in the constitution of this hyperostosis, this osteopathy may be considered as an hyperplastic, monodermic mesenchymatous, pluritissular tumour. The numerous works concerning the "avian hyperostosis osteopetrosis" are commented.

[Influence of B locus on avian viral induced tumours]. / Influence du locus B sur les tumeurs virales aviaires.

Since early in the century Avian Cancers were described as induced by viruses which later were known of DNA and RNA types. The susceptibility of birds was found different according to the genetic lines of the chickens and specially to the B locus blood group. Since the B locus of birds was strongly associated with the Major Histocompatibility Complex (MHC) it was of interest to review the last reports on the influence of the B locus on viral induced tumours. In Marek's Disease due to a DNA virus (Herpes type) the B21 allele expresses the greater resistance compared with other B alleles although non-B factors could be involved as demonstrated with the lymphocyte factor Ly-4. The possible mechanisms of the influence of B locus on the resistance against Marek's Disease are discussed. The tumours induced by RNA viruses (Avian Leucosis Sarcomas) develop or regress following genetic characters closely related to MHC. Differences of resistance exist between B alleles. Complementary genes should be present to fully express the resistance. The relationship between MHC-B locus and resistance to tumors stimulates the actual assays. Since a number of parameters remain still unknown further researches should be done in order to evidence the involved mechanisms of the resistance.

The mitogenic response to concanavalin A of Muscovy duck peripheral blood lymphocytes in the early post-hatching period.

The mitogenic response of peripheral blood lymphocytes in whole blood culture was examined in the Muscovy duckling. The optimal stimulation dose was found to be between 3.75 and 7.5 microg/ml of Concanavalin A. Some evidence is presented for the ontogeny of the cellular immune response commencing at 3 weeks of age.

Pathogenicity of a Marek's disease virus for chickens vaccinated with graded doses of herpesvirus of turkeys.

Six different groups of one-day-old chickens were vaccinated with herpesvirus of turkeys (HVT) vaccine at doses of 0, 4, 16, 64, 256 and 1,024 plaqueforming units. At 9 days of age they were challenged with an acute strain of Marek's disease herpesvirus (MDHV). Gross and microscopic lesions in nerves and gonads were investigated and combined for quantitative expression of MDHV pathogenicity. Including the microscopic lesions improved the accuracy of the HVT doses/MDHV response. The qualitative aspects of late microscopic lesions could be related to acquired resistance or to persistence of susceptibility in vaccinated chickens.

The graft-versus-host reaction in chickens: determination of some parameters.

Some aspects of the ""Graft-Versus-Host'' (GVH) reaction were studied in White Leghorn chickens by assessing the splenic response of recipients to an injection of lymphocytes from donors. The responses varied according to the origin of recipient embryos as well as to the source of the donor lymphocytes. Blood lymphocytes induced a higher splenomegaly in recipients than spleen lymphocytes, at least in the first seven weeks of life. The influence of the thymus on GVH reactions was also investigated. Lymphocytes from thymectomized chickens induced stronger responses than lymphocytes from non-thymectomized ones. These results support the conclusion that in the chicken T-lymphocytes may not be the only cells involved in the development of GVH reactions and cast some doubts on the reliability of GVH reactions to check the T specificity of immunological cellular responses.

[Thymectomy and lymphocyte mediated cytotoxicity in the chicken (author's transl)]. / Influence de la thymectomie sur la cytotoxicité à médiation lymphocytaire chez le poulet.

Spleen and blood lymphocytes from non-thymectomized chicken immunized with sheep red blood cells are cytotoxic in vitro against 51Cr-labelled sheep red blood cells with specific lysis values in the order of 40%. Complete Freund's adjuvant is necessary to obtain a measurable degree of specific lysis. Spleen and blood from immunized thymectomized chicken yield little or no cytotoxic lymphocytes, with specific lysis values inferior to 15%, whatever the number of added lymphocytes.

[Detection, by direct lymphocyte immunocytotoxicity, of antigens in cells transformed by Rous virus]. / Détection par immunocytotoxicité lymphocytaire directe des antigénes de cellules transformées par le virus de Rous.

The hamster cells transformed by the Rous Sarcoma Virus (V.S.R.) evidenced surface antigenic alterations that were detected by a method of cellular mediated immunocytotoxicity. Immune hamster lymphocytes were added to tritiated proline prelabeled target cells. These lymphocytes were able to lyse specifically the V.S.R. transformed cells.

Virus replication and cell modifications in organ cultures of tumor tissue from chickens with Marek's disease.

Organ cultures of lymphomas from chickens infected with Marek's disease (MD) virus were examined by electron microscopy at various periods after explantation. Non-enveloped herpes-type virions were observed in explants 18 days after the culture was initiated. Cytolytic virus was replicated often in lymphoblastoid cells and occasionally in other cell types (permissive and nonpermissive transformed). The permissive cells were numerous, but nonpermissive transformed cells were also present as indicated by the longevity of some cultures. The presence of both permissive and transformed cell types in the organ cultures and reasons for their sequential appearance were discussed. The results unequivocally demonstrated that lymphoid cells of tumors induced by MD virus were sites of virus replication under proper culture conditions.