Bryan Strain Of Rous Sarcoma Virus Research Articles

Complementary approaches to understanding the role of proteases and their natural inhibitors in neoplastic development: retrospect and prospect.

A great deal of evidence has accumulated in recent years for an important but complex role for proteases in tumor development. However, attempts to treat cancer in humans with anti-proteases have been disappointing, and it has been suggested that more basic groundwork is needed before anti-proteases can be effectively applied. Considerable basic information comes from the recognition that earlier results on transformation of chicken embryo fibroblasts (CEF) by the Bryan strain of Rous sarcoma virus (B-RSV) can be explained in terms of proteases and their inhibitors. In particular, the full but reversible normalization of discrete transformed foci by appropriate concentrations of fetal bovine or of calf serum implies a causal role for multiple proteases in transformation, and the efficacy of treatment with a physiological balance of their natural inhibitors. Addition of certain proteases to contact-inhibited normal cultures was then found to stimulate their proliferation. The toxicity of medium produced by CEF heavily transformed with B-RSV suggests that cachexia and other systemic effects of human cancer may result from vascular dissemination of peptides from pericellular proteolysis within tumors. Comprehensive studies revealed significant increases of plasminogen activator and matrix metalloproteinases (MMPs) after infection of CEF with other strains of RSV, and correlation of the proteases with aspects of transformation. A similar role for proteases is indicated in the transformation of mammalian cells by chemical and physical agents. The information gained from functional experiments on cell transformation in culture is complementary to that obtained from the molecular identification of proteases and their inhibitors in all stages of tumor development. The speed, quantification and easy manipulation of the RSV-CEF transformation assay can be combined with current methods of characterizing proteases and anti-proteases to further enrich our basic knowledge of neoplastic development in cells, and facilitate its application to the treatment of cancer.

Hatchability and mortality following infection of chick embryos with subgroup a rous sarcoma virus

An investigation, using Rhode Island Red, New Hampshire, Columbian and Australorp, was conducted to study the correlation between chorioallantoic membrane (CAM)-infection phenotype to challenge with Bryan strain of Rous sarcoma virus (BS-RSV) of subgroup A and subsequent mortality, following hatching. A total of 806 CAMs and 438 chicks over nine hatch-replicates in three experiments provided evidence that infection via an inoculation of the CAM induced rapid and high mortality, about 72%, averaged over the four breeds, from a fibrosarcomatous liver tumour (LT) in CAM-susceptible chicks. In contrast, only 14% of chicks inoculated via the yolk sac died from liver tumours. Infection via the CAM reduced hatchability by about 28% (P<0.01) as compared to the hatchability of embryos infected via the yolk sac. About 21% of chicks which developed no pocks on the CAM after RSV inoculation developed liver tumours and died.

Studies on Recombination in Heterologous Crosses of Rous Sarcoma Virus

Ts mutants in src from the Prague and Schmidt-Ruppin strains of Rous sarcoma virus (RSV) were used to superinfect chicken and quail cells chronically infected with the Bryan strain of RSV. No wild-type recombinants and few double-defective virions were produced. These results indicate that genetic recombination does not occur with high frequency in these heterologous crosses even if all infectious virus is derived from doubly infected cells.

Genetic control of susceptibility to an a subgroup sarcoma virus in commercial chickens

Sykes Line A White Leghorn and Line B Rhode Island Red embryos had differences in the average pock counts on the chorio-allantoic membrane (CAM) after infection with the Bryan strain of Rous sarcoma Virus (BS-RSV). By crossing the two lines 2610 embryos comprising 38 sire families were obtained. After challenge of their CAMs with BS-RSV analysis of the number of resulting pocks was made to determine whether or not the CAM response, a numerical trait, was controlled by simple Mendelian inheritance in commercial fowl. It was shown by appropriate statistical models that the trait was mainly controlled by a single pair of genes. However evidence in favour of other genes having a minor influence was also present in these lines of chicken.

Mechanism of oncogenic transformation by Rous sarcoma virus. I. Intracellular inactivation of cell-transforming ability of Rous sarcoma virus by 5-bromodeoxyuridine and light.

Chick embryo fibroblasts brought into stationary phase of growth by maintenance in serum-free Eagle's MEM medium were infected with the Bryan strain of Rous sarcoma virus (B-RSV) and incubated for 18 hr in the presence of 5-bromo-deoxyuridine (BUdR). The cells were then allowed to resume growth and deoxyribonucleic acid (DNA) synthesis by addition of an enriched F12 medium containing serum and RSV antibody to prevent spread of viral infection. After 48 hr, the cultures were exposed for various periods to visible light, overlaid with solid culture medium, and observed for the appearance of foci of transformed cells. In cultures treated with BUdR at the time of infection, exposure to light resulted in a suppression of focus formation of from 50 to 90% in various experiments. Treatment with BUdR for 18 hr before infection or on the day after infection, followed by exposure to light, had no effect on focus formation. In cultures in which almost all cells were infected, treatment with BUdR followed by exposure to light did not result in cell death. This suggests that suppression of transformation is not due to selective killing of infected cells by this treatment but rather to the intracellular inactivation of the transforming ability of Rous sarcoma proviral DNA.

The nucleic acid from avian myeloblastosis virus compared with the RNA from the Bryan strain of Rous sarcoma virus.

This paper describes properties of the nucleic acid isolated from the avian myeloblastosis virus (AMV) and compares this nucleic acid with the RNA from the Bryan strain of Rous sarcoma virus (RSV) and its helper virus, Rous associated virus (RAV). The Bryan strain of RSV is defective' and infected cells do not produce mature RSV unless simultaneously infected with an avian leukosis virus such as Rous associated virus (RAV) which functions as helper virus and presumably provides a protein coat for RSV.2 For this reason all preparations of RSV contain a helper virus which is usually present in 4-10 times higher concentrationl 3' 4 of infectious particles than RSV and which has coat properties indistinguishable from those of RSV. Because of the similar properties, RSV has not been separated from its helper virus.4 A recent report from this laboratory5 describes the purification of the mixture designated RSV + RAV and the isolation and preliminary characterization of the viral RNA. Avian myeloblastosis virus, like RAV, is an avian leukosis virus and the two are closely related biologically. Both will function as helper viruses for RSV,2 6 interfere with RSV,4 and produce tumors in chickens. They differ in specific antigens, and only AMV produces acute myeloblastic leukemia.7 The intact virus particles have been shown to have similar morphology, chemical composition, and physical properties.7' 8 Because of the close relation, it might be expected that the two would have similar nucleic acids. However, previous reports9' 10 describe only lowmolecular-weight RNA isolated from AMV, and each of several reports-3 reveals a different RNA base composition. In the present study we find the nucleic acids of AMV and RSV + RAV to be single-stranded RNA, indistinguishable in sedimentation behavior and change in conformation with change in salt concentration and very similar in base composition. Methods and Materials.--Viruses: An AMY strain, kindly supplied by Dr. P. K. Vogt, belonging to the BAI strain A and to the B classification of Vogt,7 and RSV + RAV-86 were used. Production of AMV: Chick embryos on the 12th day of incubation were inoculated intravenously'4 with 104 converting units5 of AMY and allowed to hatch. The chicks that showed a very high leukemic cell count (5 X 105 or more per mm3) in the peripheral blood 10 days after hatching were exsanguinated by cardiac puncture. The blood was collected into hepariin and centrifuged at low speed to pack the cells. The leukemic myeloblasts forming the upper two thirds of the packed cell layer were distinctly separated from the lower layer of erythrocytes. The leukemic cells were isolated and resuspended at a concentration of 1-5 X 106 cells per ml in nutrient medium.5 Ten ml of cell suspension in a 100-mm plastic tissue culture dish was incubated at 40?C in a humidified incubator flushed with a C02-air mixture to maintain the culture pH around 7.3. The cells did not attach to the floor of the plate. At approximately 12-hr intervals for 48-96 hr the cells were removed from the medium by low-speed centrifugation and resuspended in fresh medium. The medium recovered after each period of incubation was centrifuged a second time at 2,000 X g for 15 min to remove cell debris and was then frozen at 80?C until used for virus purification at a later time. Such medium contained about 105 converting units per ml.