Analysis of oncornavirus RNA subunits by electron microscopy

Size and secondary structure of avian myeloblastosis virus associated ribosomal RNA: comparison with cellular and precursor ribosomal RNA

Ribosomal RNA isolated from ribosomes present inside avian myeloblastosis virus (AMV) was characterized by electron microscopy using the formamide-urea spreading technique. The molecular weight and the secondary structures were compared with those of r-RNA and precursor r-NA isolated from host cells, the leukemic myeloblasts. The molecular weight of viral r-RNA (1.62 +/- 0.18 X 10(6) and 0.69 +/- 0.10 X 10(6)) and the molecular weight of cellular r-RNA (1.63 +/- 0.18 X 10(6) and 0.67 +/- 0.09 X 10(6)), the latter obtained from avian myeloblasts, were found to be identical and comparable with the molecular weight of chicken liver r-RNA. Likewise, the secondary structures of viral r-RNA were identical to those of cellular r-RNA. The postulated possible precursor character of viral r-RNA was excluded, since the molecules of viral r-RNA do not show any similarity to those of precursor r-RNA. Previously observed differences in behavior of viral and cellular (myeloblastic) r-RNA in sedimentation and electrophoretic mobility are discussed.

Inhibition of Rous sarcoma virus replication and cell transformation by a specific oligodeoxynucleotide

The tridecamer d(A-A-T-G-G-T-A-A-A-A-T-G-G), which is complementary to 13 nucleotides of the 3'- and 5'-reiterated terminal sequences of Rous sarcoma virus 35S RNA, was added to chick embryo fibroblast tissue cultures infected with Rous sarcoma virus. Inhibition of virus production resulted. The inference emerges that the tridecamer and its counterpart with blocked 3'- and 5'-hydroxyl termini enter the chick fibroblast cells, hybridize with the terminal reiterated sequences at the 3' and 5' ends of the 35S RNA, and interfere with one or more steps involved in viral production and cell transformation. Likely sites of action are (i) the circularization step of the proviral DNA intermediate, and (ii) the initiation of translation, the latter being described in the following communication [Stephenson, M. L. & Zamecnik, P. C. (1978) Proc. Natl. Acad. Sci. USA 75, 285--288].

Inhibition of Rous sarcoma virus replication and cell transformation by a specific oligodeoxynucleotide

The tridecamer d(A-A-T-G-G-T-A-A-A-A-T-G-G), which is complementary to 13 nucleotides of the 3'- and 5'-reiterated terminal sequences of Rous sarcoma virus 35S RNA, was added to chick embryo fibroblast tissue cultures infected with Rous sarcoma virus. Inhibition of virus production resulted. The inference emerges that the tridecamer and its counterpart with blocked 3'- and 5'-hydroxyl termini enter the chick fibroblast cells, hybridize with the terminal reiterated sequences at the 3' and 5' ends of the 35S RNA, and interfere with one or more steps involved in viral production and cell transformation. Likely sites of action are (i) the circularization step of the proviral DNA intermediate, and (ii) the initiation of translation, the latter being described in the following communication [Stephenson, M. L. & Zamecnik, P. C. (1978) Proc. Natl. Acad. Sci. USA 75, 285--288].

Inhibition of Rous sarcoma viral RNA translation by a specific oligodeoxyribonucleotide

A tridecamer oligodeoxynucleotide, d(A-A-T-G-G-T-A-A-A-A-T-G-G), which is complementary to reiterated 3'- and 5'-terminal nucleotides of Rous sarcoma virus 35S RNA, is an efficient inhibitor of the translation of proteins specified by the viral RNA in the wheat embryo cell-free system. The inhibition specificity for oncornavirus RNA is greater than for rabbit reticulocyte mRNA or brome mosaic virus RNA. Other oligodeoxynucleotides of similar size have little or no specific effect on the RNA-directed translation. The tridecamer acts as a primer for the avian myeloblastosis virus DNA polymerase when Rous sarcoma virus heated 70S RNA is used as a template, offering evidence that it can hybridize to the RNA. The possible use of such an oligodeoxynucleotide hybridization competitor to inhibit Rous sarcoma virus replication is described in the preceding paper [Zamecnik, P. C. & Stephenson, M. L. (1978) Proc. Natl. Acad. Sci. USA. 75, 280--284].