Impaired resistance to bacterial infection after tumor implant is traced to lactic dehydrogenase virus

A BALB/c mouse-passaged methylcholanthrene-induced fibrosarcoma tumor caused severe impairment of resistance to systemic listeriosis. Depressed resistance expressed immediately after tumor implantation was traced to inadvertent association of tumor with lactic dehydrogenase virus. Tumor cured of virus was totally inactive.

Free viral DNA in BK virus-induced hamster tumor cells

The biological properties of nine clonal lines of BK virus-induced hamster tumor cells were studied. All clonal lines were oncogenic and showed an enhanced ability to form colonies in semisolid medium. The cells of each clonal line contained T antigen; no virus could be rescued from any of the clonal lines. The number of viral DNA copies was determined in three of the clonal lines and varied from 10 to 20 copies per diploid amount of cell DNA. The state of the viral genome was studied in these lines, and the great majority of the viral DNA molecules appeared to be present as free (nonintegrated) molecules. At least six length classes of free defective BK virus DNA molecules, which all lacked a part of the late region of the genome, were detected in these cells. Three of the six length classes of BK virus DNA molecules acquired a TaqI recognition site, which suggested substitution of cellular DNA.

Continuous tissue culture cell lines derived from chemically induced tumors of Japanese quail

Several continuous tissue culture cell lines were established from methylcholanthrene-induced fibrosarcomas of Japanese quail. The lines consist either of fibroblastic elements, round refractile cells or polygonal cells. They show transformed characteristics in agar colony formation and hexose uptake, and most are tumorigenic. Their cloning efficiency in plastic dishes is not increased over that of normal quail embryo fibroblasts. The quail tumor cell lines do not produce endogenous avian oncoviruses and fail to complement the Bryan high titer strain of Rous sarcoma virus; those tested lack the p27 protein of avian oncoviruses. Most of the cell lines are susceptible to subgroup A avian sarcoma viruses, but are relatively resistant to viruses of subgroups C, E and F as compared to normal quail embryo fibroblasts.

Antiviral protection by virus-immune cytotoxic T cells: infected target cells are lysed before infectious virus progeny is assembled

Virus-immune cytotoxic T cells can inhibit effectively growth of vaccinia virus in acutely infected target cells in vitro by destroying infected target cells before infectious virus progeny is assembled. Together with the fact that virus-specific T cells are demonstrable after 3 days, very early during infection, and with strong circumstantial evidence from adoptive transfer models in vivo, these data suggest that in some virus infections T cells may in fact act cytolytically in vivo to prevent virus growth and spread and be an important early antiviral effector mechanism.

Separation of cells containing R-type virus-like particles from a simian virus 40-induced hamster tumor cell line

Cells derived from a simian virus 40-induced hamster fibrosarcoma were separated into two distinct cell bands of differing buoyant densities. The lighter cell band or fraction (F1) had a buoyant density range of 1.025-1.032 g/ml and comprised 3.8% of the total cells applied to the gradient, whereas the heavier cell fraction (F2) had a buoyant density range of 1.054-1.074 g/ml and comprised 95.3% of the total cells applied. Both cell fractions were tumorigenic and did not differ greatly in cell type, viability, mitotic index, or their ability to incorporate [3H]thymidine. However, ultrastructurally, the F1 cells contained R-type virus-like particles within dilated intracisternal spaces and exhibited cytoplasmic vacuoles. In the F2 cells, few detectable R-type particles and cytoplasmic vacuoles were revealed by electron microscopy. The F2 cells demonstrated a twofold greater ability to incorporate [14C]protein hydrolysate into proteins than did the F1 cells.

Cytogenetic, cytological, and virological characteristics of a bovine fibrosarcoma

The features of a bovine tumor with typical histopathological characteristics of a malignant fibrosarcoma are described. Direct karyotype preparations from the tumor tissue showed two populations of cells with bizarre karyotypes. An in vitro cell culture, designated BS-2, derived from the tumor had a normal diploid karyotype. This culture formed syncytia and produced a virus morphologically indistinguishable from the ubiquitous bovine syncytial virus. BS-2 cells reacted strongly in immunofluorescent tests with both bovine syncytial virus reference serum and serum from the tumorous cow. The virus was also demonstrated by immunofluorescence and mixed culture techniques in the buffy coat cells of the same cow.

Infective transmission and characterisation of a C-type virus released by cultured human myeloid leukaemia cells

A C-type virus isolated from long term cultures of myeloid cells from a patient with acute myelogenous leukaemia is infectious for a wide variety of cells. The establishment of chronically infected cells enabled us to characterise the virus by biological, immunological, and biochemical tests. The virus is closely related to the simian sarcoma-associated virus isolated from a woolly monkey fibrosarcoma.

Regression of feline sarcoma virus-induced sarcomas in dogs. I. Morphologic investigations

In a study of morphologic changes in the development and regression of feline sarcoma virus (FeSV)-induced tumors in dogs, 27 weaned and newborn beagle and mongrel puppies were inoculated with FeSV in doses from 1.0 to 3.0 gEq; 2 beagle and 2 mongrel puppies were used as uninoculated contact controls. All animals were examined daily, and crude tumor volume was calculated from length, width, and depth measurements of the neoplasms. Biopsies were done at various stages of tumor development and regression. When tumors were no longer palpable, all puppies were necropsied. Two of 8 (25%) weaned beagle puppies, 10 of 12 (83%) newborn beagles, and 1 of 7 (14%) newborn mongrels developed tumors, all histologically confirmed fibrosarcomas. No metastatic tumor foci were detected. The tumor life-span was divided into approximately equal periods of growth and regression. The initial regression period was characterized by focal necrosis and accompanying neutrophil infiltration. The later stages of regression were characterized by lymphocytic or mixed mononuclear infiltrates. Thus the regression histopathology was not uniform and suggested that different immunologic mediation systems effect regression. Nonneoplastic morphologic changes consisted largely of lymphoid depletion and necrosis in lymph nodes and thymus after inoculation.

Regression of feline sarcoma virus-induced sarcomas in dogs. II. Immunologic investigations

The serial development of cell-mediated immunity (CMI), cytotoxic antibody activity, serum blocking activity, and virus-neutralizing antibody levels were monitored in vitro for beagle and mongrel puppies inoculated with feline sarcoma virus (FeSV) and were compared to in vivo histologic markers of regression of induced sarcomas. CMI developed rapidly and maintained a high level of in vitro activity throughout the tumor life-span. Cytotoxic antibody levels similarly rose rapidly to peak just before clinically detectable regression and then declined during most of the regression sequence. This suggested antibody fixation at the tumor site, correlating with the histologic finding of focal necrosis and neutrophilic infiltrates. Inactivation of antibody by circulating antigen with subsequent immune complex formation was a possibility. Levels of virus-neutralizing antibody in sera paralleled those of cytotoxic antibody; their relationship in the circulation was not clear, but each related to virus-determined antigenic specificities. Serum blocking activity rose rapidly, leveled off during most of the tumor life-span, and rose slightly during the last stages of regression. This partly explained the lack of in vivo tumor lymphoid infiltrates to correlate with the striking in vitro CMI. Blocking activity was also present, however, when lymphoid infiltrates were seen histologically. Thus in vitro-in vivo correlation was best for cytotoxic antibody, which suggested that antigen-antibody reactions involving neutrophil-mediated regression sequences were important in effecting tumor-cell destruction.

Antigenic characterization of type C RNA virus isolates of gibbon apes

Type C RNA viruses initially isolated from a lymphosarcoma of a gibbon ape and from a fibrosarcoma of a woolly monkey are very closely related immunologically. However, recent studies have shown that these viruses are distinguishable in a radioimmunoassay for the 12,000-molecular-weight polypeptide (p12) of the woolly monkey virus. In the present report, an immunoassay has been developed for the p12 polypeptide of the gibbon ape type C virus. This assay is shown to further distinguish the woolly monkey and gibbon ape viruses. In type-specific assays for the p12 polypeptides of these viruses, two new type C viruses isolated from gibbons in a second colony, characterized by high incidence of hemopoietic neoplasia, are immunologically distinguishable from the original gibbon ape virus. The p12 type-specific immunoassays described in the present report may be of importance in studying the natural history of these viruses and their relationship to tumors of primates.

Search for C-type particles in human neoplasia

The salient biologic and morphologic characteristics of RNA tumor (oncornavirus) virus are reviewed. The ultrastructure of replicating oncornaviruses is illustrated in detail. C-type particles wide spread in at least three orders of animals were sighted in human sarcomas and leukemias. One case, an infantile fibrosarcoma, is presented from our cases surveyed for the presence of C-type particles. Tissue cultures derived from this tumor contained viral particles and had an elevated reverse transcriptase activity associated with the presence of 70 S RNA. The particles were larger (125 to 150nm) than those of the murine or avian Type C particles.

Primate and murine type-C viral nucleic acid association kinetics: analysis of model systems and natural tissues

Hybridization studies employing single-stranded (3)H-DNA transcripts of type-C viruses isolated from a woolly monkey or gibbon ape failed to detect nucleic acid sequences homologous to these viruses in the DNA from a variety of uninfected primate species. The possible significance of these results for the epidemiology of type-C viruses in primates is discussed.

Continuous propagation of radiation leukemia virus on a C57BL mouse-embryo fibroblast line, with attenuation of leukemogenic activity

The radiation leukemia virus (RadLV), a murine leukemia virus derived from thymic lymphomas induced by x-irradiation in strain C57BL/Ka mice, has been successfully propagated in sustained high titer in vitro in a newly established line, BL-5, of C57BL/Ka mouse-embryo fibroblasts. In addition, the production of endogenous virus, presumed to be RadLV, has been induced and sustained through multiple serial passages after treatment of BL-5 cell cultures with 5-bromodeoxyuridine. The chronically RadLV-infected subline, designated BL-5 (RadLV), sheds virus into the supernatant culture fluids that is biologically active in vitro in the XC cell plaque assay, in interference assays for focus-formation by murine sarcoma virus, and in the intracellular induction of group-specific antigens detectable by immunofluorescence, but is apparently devoid of leukemogenic activity after intrathymic inoculation into neonatal or immunosuppressed C57BL/Ka mice. Although BL-5 cells exhibited morphological alterations suggestive of transformation in vitro and gave rise to fibrosarcomatous ascites tumors after intraperitoneal inoculation with C57BL/Ka mice, the chronically infected BL-5(RadLV) cells remained normal in morphology and failed to yield fibrosarcomas in vivo.