Biphasic production of immune interferon during mitogen-induced blastogenesis of human peripheral blood mononuclear leukocytes.

Peripheral blood mononuclear leukocytes of 14 healthy blood donors stimulated by concanavalin A were shown to exhibit a biphasic pattern of the production kinetics of interferon. Maximum interferon titers were determined in the culture supernatants 8 and 48 h after addition of the mitogen. Both the early and late interferon production could be abolished by actinomycin D treatment of the induced cells implying that they depend on mitogen-stimulated de novo synthesis of cellular RNA.

[Improved test for the detection of reverse transcriptase of bovine leukosis virus].

The revertase test with exogenous matrix, poly-(rA) . oligo-(dT), for the detection of bovine leukemia virus from crude virus sediments was standardised and miniaturised. An amount of 10 ml of cell culture supernatant of short-term cultured lymphocytes (5 .

Purification and characterization of bovine leukemia virus DNA polymerase.

An RNA-directed DNA polymerase was purified from bovine leukemia virus (BLV) by successive glycerol gradient centrifugation, column chromatography on phosphocellulose and gel filtration on Sephadex G-200. The purified DNA polymerase transcribes heteropolymeric regions of 30--40 S RNA isolated from avian myeloblastosis virus. The enzyme differs from other known DNA polymerases of mammalian type-C RNA tumor viruses by the following properties: 1.

[Structures of oncornaviruses of C-typ-negativ staining technique by electron microscopy (author's transl)].

Typ-C viruses of bovine enzootic leucosis and other typ-C viruses were demonstrated by negativ staining technique and also the RNA-protein complex respectively the nucleocapsid of helical symmetry in the shape of coral bead. Now the well defined morphology of the typ-C viruses enable to identificate to be used in electron microscopy practice.