Major histocompatibility complex class II (Ia-like) antigens on chicken embryo fibroblasts: effect of transformation by Rous sarcoma virus.

In this study, three monomorphic monoclonal antibodies to chicken MHC class II molecules (B-L) were tested for reactivity in normal and RSV-transformed embryo fibroblasts. The immunocytochemical staining, the cell-bound ELISA assay, and the immunoprecipitation analysis showed that all three antibodies reacted with the B-L (Ia-like) molecules on normal cells of different genotypes. Conversely, the expression of these antigens was not detected in fibroblasts cultured from feather follicles of adult birds.

Inhibition of HLA class I antigen and mRNA expression induced by Rous sarcoma virus in transformed human fibroblasts.

Cells from various human nonlymphoreticular neoplasms show reduced HLA class I antigen expression. In this report, a system of human fibroblasts transformed by an avian retrovirus has been employed to investigate the mechanism of this phenomenon. Rous sarcoma virus has been used to transform in vitro human dermal fibroblasts, and clonal cell lines have been established from these cultures.

Reduced expression of MHC class I antigens in chicken fibroblasts transformed by Rous sarcoma virus.

Monoclonal monomorphic as well as polyclonal antibodies against H-B class I (B-F) antigen were used to evaluate the expression of these molecules on normal and RSV-transformed chick embryo fibroblasts. The results indicate that chicken fibroblasts transformed in vitro by the Schmidt-Ruppin strain Rous sarcoma virus of subgroup B (SR-RSV-B) present reduced H-B class I antigen expression as compared to uninfected cells of the same inbred strain. This quantitative reduction was observed at the cell membrane and in whole cell lysates.

[Changes of the expression of histocompatibility (HLA) antigens in human fibroblasts transformed by the avian leukosis-sarcoma virus].

Monoclonal monomorphic antibodies anti-HLA class I and II antigens, were used to evaluate the expression of these molecules on normal and RSV-transformed human fibroblasts. The results indicate that the human diploid fibroblasts transformed in vitro by RSV present a reduced HLA-class I antigens expression as compared to the uninfected fibroblasts of the same donor. In parallel, it is demonstrated that the class II molecules absent on normal cells are expressed after transformation.

[Comparative ultrastructure of human gliomas and experimental gliomas induced by Rous sarcoma virus (RSV) (author's transl)].

A brief review of earlier results concerning the ultrastructure of 20 gliomas induced by intracerebral inoculation of Rous sarcoma virus in the dog emphasizes the similarity of certain canine and human histological types. Since no sign of the viral induction is recognizable for certain in the experimental tumors and since the large size of the animal authorizes the use of the same radiological detection techniques as in Man these viral induced tumors represent a remarkable experimental model.

Nucleolar ultrastructure and transcription of preribosomal RNA in Rous sarcoma virus-transformed chick embryo fibroblasts treated with alpha-amanitin.

Uninfected and Rous sarcoma virus (RSV)-transformed chick embryo fibroblasts (CEF) were exposed to various concentrations of alpha-amanitin for different lengths of time. At a concentration of 4 micrograms alpha-amanitin/ml, RSV-transformed cells were shown to maintain a normal rate of transcription of all classes of RNA, whereas in uninfected cells transcription was reduced to a very low level. These observations cannot be accounted for by a difference in the penetration rate of alpha-amanitin through the plasma membrane.

Immunoelectron microscopic localization of Rous sarcoma virus structural protein p27 in infected chicken embryo fibroblasts.

The immunoperoxidase technique was employed to localize, at the ultrastructural level, protein Pr76 (a precursor of the 'gag' gene protein of avian leukemia and sarcoma viruses) in chick embryo cells infected with RSV-RAV-2 virus. The protein was confined to free and membrane-bound ribosomes. This was often particularly conspicuous in the perinuclear region.

Recent data and significance of intracisternal tubular inclusions in human and animal cells.

In 24 out of 60 patients with nasopharyngeal carcinoma (NPC) the cells were shown to contain a tubulo-reticular network in the dilated cisternae of the ergastoplasm which corresponds to the entity described previously as "intracisternal-tubular inclusion" (ITI). The significance of such inclusions is discussed in different pathological conditions and the literature is reviewed. This is the first report of such inclusions in nasopharyngeal carcinoma.

[Morphology of ribosomal RNA in chicken fibroblasts].

It is shown with the electron microscope that the 28 S RNA component of the ribosomal RNA extracted from Chicken fibroblasts contains secondary structures which are not present in the 18S component.

Transformation in vitro of glial hamster cells by Rous sarcoma virus.

Cell lines from the brains of inbred CF hamster embryos were established in vitro. The morphology of the cells in the light and electron microscopes was that of glial cells, and the cells contained the nervous system-specific protein S-100. Infection with the Schmidt-Ruppin strain of Rous sarcoma virus, subgroup B, resulted in foci of transformation.

Partial characterization of a herpes-type virus (K9V) derived from Kaposi's sarcoma.

A herpes-type virus that was originally isolated from a cell culture (designated K9V) derived from a tumor biopsy specimen from a patient with Kaposi's sarcoma was partially characterized. The host range of K9V, as determined by the induction of virus-specific cytopathology, synthesis of antigens, and plaque formation, was limited to human cells and particularly to fibroblasts. Immunofluorescence and complement fixation assays confirmed the specificity of the presence of cytomegalovirus (CMV)-type antigens in K9V-infected human fibroblasts.

A quantitative autoradiographic study of nucleolus-associated RNA and DNA synthesis during the eclipse phase in Rous sarcoma virus-infected chicken fibroblasts.

Functional and morphologic differences between the sensitivity of nucleoli of Rous sarcoma virus-transformed cells and that of newly infected cells to the action of actinomycin D (AD) have been demonstrated by quantitative light and electron microscope autoradiography and utilized to investigate the function of the nucleolus in the early stages of infection. After a pulse exposure to low doses of AD, increased RNA synthesis is induced within 80 minutes in the fibrillar portion of the nucleolus by infection. A concomitant increase in the retention of tritiated AD in the nucleolus and a quantitative redistribution of intranuclear and cytoplasmic DNA label are interpreted as evidence for a virus-induced amplification of the binding sites of AD in nucleolar chromatin.

Cytomegalovirus: nucleocapsid assembly and core structure.

New ultrastructual aspects of cytomegalovirus nucleocapsid assembly are illustrated in cells from a Kaposi sarcoma. The occurrence of viral deoxyribonucleoproteins in the form of strands and penetration of these strands into open capsids is illustrated. The geometrical arrangement of the core material of the nucleocapsid is aslo emphasized.