Feline leukemia and RD-114 virus group-specific proteins: comparison of amino terminal sequence.

The major internal virion polypeptide from feline and RD-114 type C viruses has been subjected to amino terminal sequence analyses with the Beckman automated sequencer. These proteins, as well as their homologs in rat and mouse viruses, begin with the sequence prolylleucylarginyl (Pro-Leu-Arg). Virus RD-114 differs from conventional feline type C viruses that show about 80 percent relatedness based on calculation of the minimum number of base changes to give equivalent coding for the protein segments analyzed. In addition, insertion of a gap in the RD-114 sequence is necessary to maintain positional homology. The difference between RD-114 and feline leukemia virus appears as great as the difference between mouse type C viruses and either of these two viruses. Thus, even though current evidence suggests that RD-114 is of feline origin, the sequence differences between RD-114 and conventional feline virus group-specific proteins is well beyond that based on one or a few point mutations.

Molecular relatedness of mammalian RNA tumor viruses as determined by DNA hybridization.

Each of six mammalian C-type viruses-including two feline leukemia viruses, three murine leukemia viruses, and the human "candidate" virus RD-114-can be distinguished from each other by hybridizing DNA synthesized by viral reverse transcriptase with viral RNA. Characterization of the DNA . RNA hybrids by hydroxylapatite chromatography revealed nucleotide sequence diversity among the viruses, detectable both by the amount of cross-hybridization and by the decreased thermal stability of heterologous hybrids.

Simultaneous detection of reverse transcriptase and high molecular weight RNA unique to oncogenic RNA viruses.

The simultaneous assay of the reverse transcriptase and 60S to 70S RNA of oncogenic RNA viruses is described. The virus can be detected at low concentrations in biological fluids containing enzymatically active cell fragments or other contaminants. The fact that two features diagnostic of the oncornaviruses are used in the tests increases the certainty with which a positive outcome can be interpreted.

Identification and isolation of the major core protein from the oncornavirus-like particle in human milk.

Subviral cores have been prepared from the oncornavirus-like particle found in human milks with the use of phospholipase C and ether or Sterox SL. The major protein of these cores has a molecular weight of 27,000 daltons, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This protein is found in the core fractions of reverse transcriptase-positive milks and is absent in negative milks. It is distributed in sucrose gradients only in those fractions containing cores and reverse transcriptase activity. The major core protein of the human milk oncornavirus-like particle is electrophoretically identical to the major core protein of the mouse mammary tumor virus.

Physical, chemical and serological properties of C-type virus associated with transplantable rat Thurzo-Svee leukemia.

Cells of rat Thurzo-Svee leukemia produce C-type virus. Viral particles are shown to contain high-molecular weight RNA and RNA-dependent DNA polymerase the virus possesses mammalian gs-3 antigen and rat species-specific gs-1 antigen and thus appears to be of rat origin.

Hemagglutinating properties of CELO, an oncogenic avian adenovirus.

Chicken-embryo-lethal-orphan (CELO) virus, Phelps strain, agglutinated erythrocytes at 37 C. The hemagglutinating activity, which is a function of complete and incomplete virus particles, was sensitive to heat but not to pH. The soluble components of the virus were similar in sedimentation characteristics to those obtained from human adenovirus type 1. The effects of chemical and physical agents on CELO hemagglutinin, CELO infectivity, and red-cell receptors suggested that the last were protein in nature and that cell-virus attachment was mediated by amino groups on the virion. The attachment of virus to red blood cells via the penton projection was demonstrated by electron microscopy.

Oncogenic and nononcogenic bovine adenoviruses and guanine-cytosine content of their DNA.

Bovine adenoviruses types 1, 2, and 3 were purified and concentrated by polyethylene glycol precipitation and CsCl density-gradient centrifugation. The efficiency of recovery of infective particles was 64 to 80%. The guanine-cytosine contents of DNA of the nononcogenic types 1 and 2 and the highly oncogenic type 3 were found to be 62, 61, and 48%, respectively--a pattern similar to that of nononcogenic and oncogenic human adenoviruses.

[The types of virus-specific structures in cells of human origin producing oncornaviruses]. / Dva tipa virusspetsificheskikh struktur v kletkakh cheloveka, produtsiruiushchikh onkornavirus

In the cell cytoplasm of human tissue cultures Detroit-6 and AO which produce B type oncorna-virus, two types of virus-specific structures were revealed. Structures of type I were aggregated fibrils of 3 and 6 nm diametre. Structures of type II were nucleoids of A-particles of 70-80 nm diametre. They were rather well separated from cell components by centrifugation sucrose density gradient and repeated centrifugation in the sucrose concentration gradient. Fibrils were found in the density regions of the equilibrium gradient of 1.26 and 1.19 g/cm3, whereas A-particles were detected in the sones of the density of 1.29 and 1.23-124 g/cm3. Their sedimentation coefficients in the sucrose concentration gradients were about 150S and 250S, respectively. From both structure types similar RNA classes were extracted sedimenting in 60S, 45S and 35S regions (sucrose concentration gradient). In addition, 20S RNA was found within the 150S structures. Both structures sa. However, hydridization degree of RNA isolated from both structures with DNA synthesized enzymatically on extracellular various (DNA I) and A-particles (DNA II) was different. With DNA-I, 50-80% of RNA isolated from the type I structures and less than 20% of RNA extracted from the type II structures were hybridized. At the same time, strictly opposite situation (50-80% of RNA II and 20% of RNA I) was observed for DNA-II. These data show lack of genetic connection between these types of cytoplasmic structures and possible role of type I structures in reproduction of oncorna-virus type B.

[Physicochemical properties of the DNA of simian adenovirus type 38]. / Fiziko-khimicheskie svoistva DNK adenovirusa tipa 38 obez'ian.

The sedimentation constant, specific viscosity, and the length of DNA molecule of simian adenovirus type 38 were measured and the molecular weight was estimated. The melting temperature and buoyant densities of this virus DNA in cesium chloride and cesium sulphate density gradients were determined, and the content of GC-pairs was calculated.

[Integration and expression of the oncornavirus type D genome in transplantable cells]. / Integratsiia i ekspressiia genoma onkornavirusov tipa D v perevivaemykh kletkakh

The authors investigated five cell cultures producing oncornaviruses type D by the method of molecular hybridization of viral nucleic acids with cell nucleic acids. It was shown that nuclear DNA of the cell lines under study contained scores and hundreds of viral RNA genome-equivalents, while cytoplasmatic RNA contained hundreds and thousands of viral genomes. Viruses produced by the cultures involved are found to be identical or highly similar to nucleotid sequences of their nucleic acids.