[Use of a monoclonal antibody against envelope protein gp51 of bovine leukemia virus in a test for the diagnosis of enzootic bovine leukosis]. / Verwendung eines monoklonalen Antikörpers gegen das Hüll-protein gp51 des bovinen Leukämievirus in einem Test zur Diagnose der enzootischen Rinderleukose.

A highly specific monoclonal antibody (mAb) directed against envelope protein gp51 and effectively bonding the antigen (Ag) on account of its high affinity from an unpurified Ag preparation was chosen for use in a double-sandwich enzyme immuno-assay (EIA) for diagnosis of bovine leukaemia virus (BLV). The epitopes recognised in bovine sera by the gp51-specific antibodies were at the same time properly exposed. Some parameters of major importance to testing were optimised (Ab and Ag quantities, dilution of bovine sera for testing). Preliminary testing of the double-sandwich EIA on selected bovine sera and comparison with both the immunodiffusion test and anti-BLV EIA confirmed its good diagnostic specificity and sensitivity. Hence, this double-sandwich EIA, developed by means of an mAB against gp51, on account of the possibility to use as Ag culture supernatant of the FLC cell line, is a sensitive, low-cost alternative to the anti-BLV EIA Dessau MTP which had so far been used. The double-sandwich EIA is recommended for use in final sanitation for its high analytical and diagnostic sensitivity.

[The validation of an enzyme immunoassay for the detection of antibodies to bovine leukosis virus]. / Die Validierung eines Enzymimmunoassays zum Nachweis von Antikörpern gegen das Rinderleukosevirus.

Validation of an enzyme immuno-assay for detection of antibodies against bovine leucosis virus is described in this paper. Internal standardisation of the test was done by means of a negative control serum. With absolute extinction of the negative control serum between 100 and 200 mE, a serum sample is rated positive, if its extinction is 1.5 times above the control. The methodological sensitivity of the enzyme immuno-assay described has proved to be four times as high as that of the immunodiffusion test. The results recorded at five diagnostic laboratories suggested a sensitivity of the test of 97.6 percent (92.1 to 100 percent) and a specificity of 98.1 percent (94.4 to 100 percent). The high efficiency of the test can be confirmed by immunoblotting.

[Electron microscopy studies on proliferation of foot-and-mouth disease virus in cell cultures. I. Morphologic changes in cell nucleus]. / Elektronenmikroskopische Untersuchungen zur Vermehrung des Maul-und-Klauenseuche-Virus in Zellkulturen. I. Morphologische Veränderungen am Zellkern

The first morphological indication of FMD infection of a cell culture was in the nucleus. Components of nucleoli became segregated and were finally present only as remnants. It was not possible to distinguish different stages of segregation, as in the case of entero-virus infections, because of the rapidity of FMD virus proliferation. Following changes in nucleoli there was margination of chromatin. Particularly striking was an increase in interchromatin granules. Changes in the nuclear membrane seemed to facilitate the transfer of nuclear material to the cytoplasm. Strongly pronounced dilatation of the peri-nuclear cleft, like that seen in aphthae and other tissues, were rarely visible in infected cell cultures.

[Electron microscopy studies on the proliferation of foot-and-mouth disease virus in cell cultures. II. Changes in nucleic acid metabolism of the cell nucleus]. / Elektronenmikroskopische Untersuchungen zur Vermehrung des Maul-und-Klauenseuche-Virus in Zellkulturen. II. Veränderungen im Nukleinsäurestoffwechsel des Zellkerns

BHK cells were infected with FMD virus and treated with tritium-labelled thymidine and uridine for examination by autoradiography under the electron microscope. Labelling of the DNA, examined by autoradiography under the optical microscope, showed inhibition of 3H-thymidine incorporation. For demonstrating RNA labelling of nuclei, some cells were treated with actinomycin D and others were left untreated. Under the lectron microscope there was no evidence of increased 3H-uridine incorporation in the untreated cells after virus infection, but actinomycin treatment increased RNA labelling in extranucleolar parts of the nucleus, evidently RNA synthesis independent of DNA. There was evidence of some synthesis of virus-specific RNA in the nuclei. The extent of virus-specific RNA synthesis in the cytoplasm was less extensive than in the nucleus.

[Electron microscopy studies on the proliferation of foot-and-mouth disease virus in cell cultures. III. Morphogenesis in cytoplasm]. / Elektronenmikroskopische Untersuchungen zur Vermehrung des Maul-und-Klauenseuche-Virus in Zellkulturen. III. Die Morphogenese im Zytoplasma

The previous parts have been concerned with the participation of the cell nucleus in the formation of the RNA of FMD virus. However, the actual morphogenesis of the virus takes place in cytoplasm. In BHK cells, changes attributable to virus infection were visible by the second hour, with the formation of threads and large polysome complexes near the nucleus. Viral particles soon appeared between these structures. There were no pronounced foci of viroplasma, and it seemed that they were not necessary. Simultaneously new membranes formed in the cell. Clumps of viral particles were next visible in the cxtoplasma. The clumps became enveloped and were transported in this way to the periphery of the cell. Elsewhere there was uptake of particles in autophagic vacuoles, an expression of cellular defensive processes. In ultra-thin sections the virions measured 21-25 nm. Within vacuoles the inner part of the virus, the nucleoid, showed greater contrast than the periphery, the capsid. At first there were only slight changes in mitochondria. Liberation of virus by cell rupture occurred only after severe damage to the cell, particularly the lysosome membranes.

[Structure of the foot-and-mouth disease virus. 2. Various physical and chemical properties of the 12S components]. / Struktur des Maul-und-Klauenseuche-Virus. 2. Einige physikalisch-chemische Eigenschaften der 12S-Komponente

The 12S units were purified by heat treatment and acidification of purified, highly-concentrated virus, with separation of viral RNA by gel filtration. The following physical parameters were obtained: - partial specific volume 0.737 +/- 0.020 g/cm3; diffusion soefficient D020,W = 3.96 +/- 0.24 F; sedimentation coefficient S020,W = 12.1 +/- 0.5S; molecular weight 283,00 +/- 30,000 Dalton; refraction increment (determined by ultracentrifugation) was dn/dc = 0.189 +/- 0.010 cm3/g for white light of the "HBO 200". Examination of the 12S component by analytical ultracentrifugation and in sucrose and CsCl gradients showed that the product was uniform; density determined in CsCl was 1.302 +/- 0,00 s g/cm3. The ultraviolet absorption spectrum was characteristic of proteins; extinction values at 278 nm in a layer 1 cm thick and 10 mg/ml at pH was 13.9 +/- 1.9, while the ratio E278 nm/E250 = 2.2. Electron microscopy showed that the diameter was 11.0 +/- 1.6 nm. Morphology of 12S unit was discussed.