Kalman Perk

Reovirus infection of young muscovy ducks (Cairina Moschata)

A viral disease of Muscovy ducks characterised by necrotic focus formation in the liver, spleen and kidneys is reported. The causal agent, grown in embryonated Muscovy duck eggs and embryo fibroblasts, was examined by electron microscopy and showed close morphological relationship to the Reoviridae. The isolate caused syncytial formation in tissue culture and failed to haemagglutinate.

The caprine arthritis-encephalitis virus is a distinct virus within the lentivirus group

The genetic relatedness among viral genomes of caprine arthritis-encephalitis virus, visna virus, and progressive pneumonia virus, was determined. Whereas the genomic RNAs of two strains of visna virus are indistinguishable as reflected both by their annealing kinetics as well as by the thermal stability of the hybrids, the caprine arthritis-encephalitis virus and visna virus have only 30% of their nucleic acid sequences in common. Furthermore, within the homologous regions of the two viral genomes, there is a significant level (approximately 10%) of mismatched base pairs. This limited homology that exists between caprine arthritis-encephalitis virus and visna virus was lower than the sequence homology observed between the genomes of visna virus and progressive pneumonia virus, or between the genomes of caprine arthritis-encephalitis virus and progressive pneumonia virus. All this indicates that caprine arthritis-encephalitis virus is an additional distinct member of the Lentivirus group of the Retroviridae family.

Isolation and preliminary characterisation of a novel retrovirus isolated from a leukaemic dog.

A novel canine retrovirus was isolated from mononuclear cells of the peripheral blood of a leukaemic dog. The main clinical and pathological findings in this dog were lethargy, anorexia, weakness, dyspnoea, severe anaemia, thrombocytopenia and a high white blood cell count, practically all of which were lymphoblasts. The virus was isolated from mononuclear cells obtained from the blood, cocultivated with indicator cells. The virus particles encode a reverse transcriptase with Mg++ preference, have a density in sucrose gradients of 1.16 g ml-1, and induce syncytia in permissive cell cultures such as Himalayan tahr ovary and canine fetal thymus lines. This agent replicates to high titres. The virus exhibits a morphogenesis and morphology typical of lentiviruses. Immunoblotting and competitive radioimmunoassays failed to detect immunological crossreactivity with other representative lentiviruses and oncoviruses of the retrovirus family.

A reverse transcriptase assay for the diagnosis of lymphoproliferative disease (LPD) of Turkeys

A reverse transcriptase assay was applied as a diagnostic test for lymphoproliferative disease (LPD) of turkeys. The assay differentiates LPD from reticuloendotheliosis (RE) on the basis of a different divalent cation-requirement of the exogenous-templated reverse transcriptase activity associated with the causative viruses. The test requires small volumes of blood, is rapid, sensitive and appropriate for the detection of LPD virus in the blood of field or experimentally infected turkeys.

Isolation and characterization of a novel retrovirus from sheep affected by pulmonary carcinoma

Sheep pulmonary carcinoma (SPC) has been shown to be associated in nature with a retrovirus, by electron microscopic, biochemical, and epidemiological criteria and by experimental transmission. In this study, a retrovirus has been isolated from SPC tumors which were experimentally induced by inoculation with a cell-free, reverse transcriptase containing fraction from a spontaneous field case of SPC, and propagated in culture. This novel virus was shown to be unrelated to murine, avian, and bovine leukemia viruses, to be exogenous to the ovine species, and to have only limited genetic relatedness to the lentiviridae (maedi-visna and caprine arthritis encephalitis virus).

Lymphoproliferative disease of turkeys: Pathogenesis, Viraemia and serum protein analysis following infection 1

Turkey poults inoculated with plasma obtained from turkeys affected with lymphoproliferative disease (LPD) developed typical lymphoproliferative lesions in the pancreas, spleen and thymus, 3 and 6 weeks post infection. Virus-associated reverse transcriptase activity in plasma reached a significant level at 3 weeks and was further elevated at 6 weeks post infection, concomitantly with a marked increase in serum IgG, 7S-immuno-globulin level. There was no alteration in serum total iron binding capacity (transferrin) level in LPD virus-infected animals, as compared to controls. Natural field cases of LPD also demonstrated elevated serum IgG levels which persisted for more than 3 months, along with viraemia. There was a significant decrease in serum albumin concentration in about 30% of the infected animals, but in few of these turkeys was total serum protein elevated due to the very marked increase in gamma-globulins (IgG).

Susceptibility of domestic birds to Lymphoproliferative disease virus (LPDV) of Turkeys 1

The susceptibility of domestic ducks, geese and chickens to infection with lymphoproliferative disease virus (LPDV) of turkeys was tested. Infection with LPDV was assayed by measuring the particle-associated DNA polymerase in plasma. Ducks and geese were not susceptible to infection with this virus. Chickens were susceptible to the infection with LPDV and some of the birds developed a persistent viraemia. Six serial passages in chickens of viraemic plasma were achieved. Lymphoproliferative gross and microscopic lesions caused by LPDV infection were less frequent and less severe in chickens than in turkeys. LPDV infection in chickens was proven by the reproduction of LPD in turkeys by inoculation of chicken viraemic plasma, and by molecular hybridisation between LPDV (3H)cDNA and RNA extracted from the plasma and organs of inoculated chickens.

Comparative susceptibility of two turkey strains to lymphoproliferative disease virus.

The susceptibility to lymphoproliferative disease (LPD) of 1-day-old and 3-week-old poults of two turkey strains (A and B) was examined. Their susceptibility to infection with the causative virus was evaluated by the level and the duration of viraemia and by the presence of gross and microscopic lymphoproliferative lesions. Although in field conditions the incidence of outbreaks of LPD in strain A turkeys was much higher than in strain B, both lines were found to be of similar susceptibility to infection under experimental conditions.

Ultrastructure of Intracytoplasmic Particles in a Burkitt’s Lymphoma Cell Line

Electron microscopic examination of a Burkitts-lymphoma-derived cell line, P3HR-1, repeatedly revealed clusters of membrane-free nucleoids within the cytoplasmic matrix. The particles possessed an electron-lucent center surrounded by two layers - a dense ring and a fuzzy broad outer layer.

Lymphoproliferative disease of turkeys: effect of chemical and surgical bursectomy on viraemia, pathogenesis and on the humoral immune response.

Turkey poults which were surgically or chemically bursectomised after hatching, and inoculated with the lymphoproliferative disease (LPD) virus at 3(1/2) weeks of age, developed typical tumourous lesions in various organs (pancreas, spleen, thymus, liver, gonads and kidneys) to the same extent as intact but inoculated controls. Plasma virus-associated reverse transcriptase activity (as an estimation of viraemia) developed at a higher rate in poults neonatally treated with 16 mg of cyclophosphamide. The chemically bursectomised birds were found to have markedly reduced serum gamma-globulins levels, and low levels or absence of agglutinins to sheep red blood cells and to killed Brucella abortus following immunisation with these antigens. Inoculation of turkey poults with LPD virus did not cause inhibition of the humoral immune response in intact birds but reduced significantly antibody production in surgically bursectomised poults. Since infection with LPD virus was previously shown to cause hypergammaglobulinaemia, and more specifically, a marked increase in serum IgG (7S) levels, it was suggested that the LPD tumour cells might be antibody-producing B-lymphoid cells. However, results presented here indicate that LPD lesions and viraemia can develop even in turkeys lacking any appreciable B-cell activity.