Biomedical subjects
Publications and source records attributed to A Yaniv.
Molecular hybridisation with radioactively labelled DNA complementary to the RNA of the maedi virus was used to probe for homologous RNA in the polysome fraction of pulmonary carcinomas (jaagiekte) of Awassi sheep. No sequence homology was detected, which suggests that maedi (or visna) virus is not implicated in the aetiology of pulmonary carcinoma of sheep.
A spontaneously transformed hamster cell line, designated Clone B (Cl B), has been activated by halogenated pyrimidines to produce oncornavirus-like particles. The optimal conditions for virus induction were studied by the analysis of culture fluids for particles with polymerase activity. Maximal enzymatic activity was induced when exponentially growing Cl B cells were treated with 20 to 30 microgram/ml 5-iodo-2'-deoxyrudine for a 24-h period. Under these conditions, the kinetics of particle release reached a maximal level between 48 and 72 h following removal of the drug, and then decreased rapidly. The induced particles exhibited features characteristic of oncogenic RNA viruses: actinomycin D was found to inhibit their induction; the particles band in sucrose gradients at a density of 1.15 g/ml; nonionic detergent treatment releases the virion core component exhibiting a buoyant density of 1.21 g/ml in sucrose gradients; the viral particles contain high molecular weight RNA species with sedimentation coefficients of 65 S and 35 S; and the polymerase associated with Cl B particles efficiently transcribes synthetic templates preferred by the reverse transcriptases of known RNA tumor viruses, but demonstrates a very low endogenous activity.
Spontaneously transformed hamster cells were examined for the presence of TSTA by employing the tumor rejection test. It was demonstrated that each of the spontaneously transformed cell lines as well as cells derived from tumors induced by these cells possess an individual distinct antigen, capable of evoking a significant anti-tumor immunity. The immunizing potential of these antigens and their specificity were not affected by either in vivo or in vitro environment. The results suggest that the spontaneously transformed hamster cells undergo antigenic modification, which resembles the TSTA of chemical-carcinogen induced tumors.
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C-type particles secreted in vivo by MOPC-315 myeloma cells were characterized. These particles localize at a density of 1-16 g/ml in sucrose and possess a 60 to 70S RNA and an RNA-instructed DNA polymerase. Endogenous enzyme activity requires manganese and is inhibited by ribonuclease or by the omission of any of the deoxynucleoside triphosphates. The enzyme utilizes the virus 60 to 70S RNA as a template to synthesize DNA molecules which specifically hybridize to the homologous RNA.
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Noninfectious particles of a mutant of Rous sarcoma virus failed to exhibit DNA polymerase activity even with the use of the most sensitive synthetic template-primer complexes. A neutralization blocking test against antibody to DNA polymerase revealed that these mutants did not contain protein immunologically related to the DNA polymerase.
Monospecific antiserum was prepared against purified deoxyribonucleic acid (DNA) polymerase from avian myeloblastosis virus (AMV). Immunodiffusion assay with purified DNA polymerase revealed that the anti-DNA polymerase serum formed one precipitation band, whereas no reaction with any of the seven major structural proteins of AMV was observed. The antiserum also demonstrated enzyme-neutralizing antibody activity that was associated with the immunoglobulin G fraction. There was no difference in the neutralization of DNA polymerase activity directed by ribonucleic acid (RNA), DNA, or RNA-DNA hybrid templates.
Monospecific antiserum prepared against the isolated deoxyribonucleic acid (DNA) polymerase of avian myeloblastosis virus (AMV) neutralized the endogenous ribonucleic acid-instructed DNA polymerase activity of detergent-disrupted virus. The viral polymerase was serologically unrelated to the seven major structural polypeptides of AMV. Furthermore, the viral enzyme was distinguished from normal cellular DNA polymerases by serological criteria; thus, antiserum against the viral enzyme neutralized its homologous antigen but not normal cellular DNA polymerases. Neutralization by antibody of viral DNA polymerase activity was observed with all avian leukemia-sarcoma viruses tested, irrespective of viral antigenic subtype. The DNA polymerase activity of avian reticuloendotheliosis virus, and of a variety of mammalian oncornaviruses, was not neutralized by antisera against the AMV polymerase. Immunological analysis of the RSValpha(O) mutant, which is deficient in DNA polymerase activity, shows this mutant to lack demonstrable polymerase antigen. Viral polymerase was identified by immunofluorescence as a cytoplasmic constituent in virus-producing chicken cells; polymerase antigen was not detected in uninfected (gs(-)) chicken cells.
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Lentiviruses are a subfamily of retroviruses which have been aetiologically linked to the induction of arthritis, encephalitis, progressive pneumonia and slow neurological diseases in certain species. Relatively little is known about their genome structure, mechanisms of pathogenesis or evolutionary relationships with other retroviral subfamilies. In an effort to understand better the mechanisms by which these viruses induce such a variety of chronic diseases, we have molecularly cloned and physically characterized the genomes of caprine arthritis-encephalitis virus (CAEV) and equine infectious anaemia virus (EIAV) (A.Y. et al., in preparation). The latter, which bears some morphological similarity to the lentiviruses, has yet to be classified definitively as one. Here, we have determined the nucleotide sequence of a highly conserved region within the CAEV and EIAV pol genes. We demonstrate a much closer relationship of their predicted pol gene products to that of the presumed aetiological agent of human acquired immune deficiency syndrome (AIDS) than to those of other retroviruses. Additional pairwise comparisons allowed us to generate an evolutionary tree showing that the pol genes of lentiviruses and oncoviruses have evolved from a common progenitor.
Turkeys inoculated at 5 weeks of age with lymphoproliferative disease (LPD) virus developed typical lesions in the spleen, thymus, and pancreas. The in vitro blastogenic response of peripheral blood lymphocytes to the mitogens phytohemagglutinin and concanavalin A was drastically (up to 90%) suppressed in the inoculated turkeys 1 to 4 weeks postinoculation compared with uninoculated controls, and even at 11 weeks the response was about 50% inhibited. A lethal (about LD33) dose of antihelminthic drug niridazole, 100 mg/kg given each day for 3 days to 4-week-old turkeys, caused a transient inhibition of the blastogenic response within 32 days of treatment, which was less pronounced than that observed in turkeys inoculated with LPD virus, whether pretreated with niridazole or not. Virus-associated reverse transcriptase activity in the plasma was significantly higher in the turkeys pretreated with niridazole, and LPD lesions developed to the same extent in the untreated and treated groups, as determined 9 weeks post virus inoculation. A sublethal dose of niridazole, 50 mg/kg given each day for 4 days, did not suppress the blastogenic response to mitogens at any time determined (starting 10 days post-treatment) and did not affect the pathogenesis of LPD and the viremia. Body weights were significantly decreased by virus infection and by treatment with lethal doses of niridazole.