Avian Rous sarcoma

Criterion 3 Moderate risk viruses are only poorly oncogenic in rodents, but avian (Rous) sarcoma virus, a low risk virus, is the... 

Certain RNA viruses, particularly retroviruses, have also proven capable of inducing cancer. Retroviruses known to induce cancer in animals include Rous sarcoma virus, Kirsten murine sarcoma virus, avian myelocytomatosis virus, as well as various murine leukaemia viruses. Thus far, the only well-characterized human RNA transforming virus is that of human T cell lymphocytotropic virus-1 (HTLV-1), which can induce adult T cell leukaemia/lymphoma (ATL). Identification of antigens uniquely associated with various tumour types, and identification of additional cancer-causing viruses, remain areas of very active research. 

Retroviruses have featured prominently in recent advances in the molecular understanding of cancer. Most retroviruses do not kill their host cells but remain integrated in the cellular DNA, replicating when the cell divides. Some retroviruses, classified as RNA tumor viruses, contain an oncogene that can cause the cell to grow abnormally (see Fig. 12-47). The first retrovirus of this type to be studied was the Rous sarcoma virus (also called avian sarcoma virus Fig. 26-31), named for F. Peyton Rous, who studied chicken tumors now known to be caused by this virus. Since the initial discovery of oncogenes by Flarold Varmus and Michael Bishop, many dozens of such genes have been found in retroviruses. 

Acute transforming retroviruses are a unique subset of retroviruses that have acquired the ability to produce cancer in rodents and avian species in a relatively short time period (several weeks). Examples of acute transforming retroviruses include the Rous sarcoma virus (RSV), which produces sarcomas in chickens, and the Harvey murine sarcoma virus (Ha-MSV), which produces sarcomas in rats and mice. Studies utilizing RSV provided the first evidence that cellular genes, now termed oncogenes, exist in vertebrate cells. 

Kitamura, N. Kitamura, A. Toyoshima, K. Hirayama, Y. Yoshida, M. Avian sarcoma virus Y73 genome sequence and structural similarity of its transforming gene product to that of Rous sarcoma virus. Nature, 297, 205-208 (1982)... 

Type D (squirrel monkey retrovirus). ALV-related virus (avian leukemia virus, rous sarcoma virus). 

Further investigations of ascorbate inhibition of virus replication have been carried out using retroviruses as models. Bissell et al. (1980), working with the avian retrovirus of chickens, found that while cell-free virus was resistant to ascorbate inactivation upon short-term treatment in vitro, exposure of virus-infected cultures to the vitamin resulted in reduction of virus replication and lowered infec-tivity of newly replicated virus. A subsequent study found that ascorbate interfered with the replication and cell-transforming potential of Rous sarcoma virus by stabilizing the differentiated state of chicken cells (Schwarz, 1991). In a lymphocytic cell line latently infected with human T-cell leukemia virus (HTLV-1), ascorbate was shown to interfere with virus production triggered by chemical inducers added to the culture medium (Blakeslee et al., 1985). 

Avian CELO (Adeno) Avian leukosis Marek s disease Rous sarcoma Lucke kidney tumor Murine leukemia Moloney Rauscher Friend Gross ... 

McDaniel, L.S., I.N. McDaniel, and H.L. Chute. 1962. Laboratory transmission of Rous sarcoma virus by Aedes aegypti. Avian Dis. 6 127-132. 

MoLV RTase). In avian sarcoma—leukosis viruses (ASLV, e.g., myeloblastosis, leukosis, Rous sarcoma), the polyprotein precursors, Gag-Pol, are produced as a result of a translational (-1) frameshift at the gag-pol junction. In mammalian retroviruses (e.g., MoLV and HIV), however, the Gag-Pol precursor is produced via an in-frame read through of a termination codon at the end of the gag gene. 

Robinson, W. S., Baluda, M. A. The nucleic acid from avian myeloblastosis virus compared with the RNA from the Bryan strain of Rous sarcoma virus. Proc. nat. Acad. Sci. (Wash.) 54, 1686-1692 (1965). 

Sarcoma viruses. This group includes avian sarcoma virus (ASV), Rous-associated virus and other fowl sarcoma viruses murine sarcoma virus (MSV) (28, 265, 454) feline sarcoma virus (FeSV) (298) and sarcoma viruses of primates, including woolly monkey (SSV) (516) and gibbon ape (GaSV). 

---