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Biomedical subjects

F Rapp

Publications and source records attributed to F Rapp.

At least 253 records · Page 14Linked to original sources
PubMed1972

Rescue of Epstein-Barr virus from somatic cell hybrids of Burkitt lymphoblastoid cells.

A Burkitt lymphoblastoid cell line, P3J-HR-1, was fused and hybridized to a human sternal marrow cell line. The somatic cell hybrids were negative when examined for Epstein-Barr virus (EBV) markers. When the hybrid cells were exposed to 5-iododeoxyuridine, both EBV-specific antigens and virus particles were induced as determined by the immunofluorescence test and by electron microscopy. The data presented suggest that the EBV genome can be transferred from a lymphoblastoid cell to another cell type during cell hybridization, that the EBV genome can persist in the hybrid cells for long periods of time, and that synthesis of the virus can be induced in the heterokaryons.

Antigens, Viral↗
PubMed1972

Latency of human measles virus in hamster cells.

A latent system employing measles virus (Schwarz strain) was developed in hamster embryo fibroblasts (HEF). Measles virus-specific antigen was detected by immunofluorescence in 30 to 50% of HEF cells, and these cells released infectious virus when co-cultivated with a susceptible monkey cell line, BSC-1 cells. No infectious virus could be detected in the cells when measures were taken to exclude passage of viable latent cells onto the indicator BSC-1 cells. Infectious center assays demonstrated that about 1 in 10 of the latently infected cells in the population could release infectious virus. Infectious virus appeared within 6 hr after co-cultivation of the HEF cells with BSC-1 cells, as compared to 24 hr required for normal replication of measles virus in the BSC-1 cells. Furthermore, labeling of progeny virus ribonucleic acid (RNA) by using tritiated uridine, and inhibition of RNA or protein synthesis by 5-azacytidine or cycloheximide suggested that neither additional RNA nor protein synthesis is required after co-cultivation of the cells to effect early virus release. It can therefore be postulated that there is a block at a late step in virus replication in the latently infected hamster cells. The most obvious site would concern maturation of infectious virions at the cell membrane.

Animals↗
PubMed1972

Cell-dependent differences in the production of infectious herpes simplex virus at a supraoptimal temperature.

The replication of herpes simplex virus (HSV) was compared in rabbit and hamster cells at optimal and supraoptimal temperatures. Replication occurred in cells of either species at 33 C, but the total infectious virus yield was routinely about 10-fold greater in rabbit cells than in hamster cells. At 39 C, this difference was exaggerated to greater than 100,000-fold. Whereas infectious virus was produced and plaques formed in rabbit kidney cell monolayers at the higher temperature, neither developed in those derived from hamster embryos. Elevating the temperature from 33 C to 39 C at various time intervals after exposure of the cultures to virus revealed that production of infectious virus in hamster cells was completely heat-sensitive up to 6 hr after infection. Specific viral antigens and viral deoxyribonucleic acid (DNA) were synthesized in both rabbit and hamster cell cultures. In addition, cellular DNA synthesis was depressed and cytopathic effects occurred in both cell systems. These cytopathic effects were not observed in cell cultures treated with HSV previously inactivated with ultraviolet light. Compared with parallel cultures at 33 C, the amount of viral DNA synthesized at 39 C was greatly reduced in both systems. In hamster cells, the reduction was twofold greater than in rabbit cells. This cell-dependent thermal inhibition of HSV replication in hamster cells did not occur with vaccinia virus.

Animals↗
PubMed1972

Absence of leukosis virus markers in hamster cells transformed by herpes simplex virus type 2.

Hamster cells which transformed after exposure to herpes simplex virus type 2 previously irradiated with ultraviolet light were tested for the presence of hamster leukosis viruses or their virus-specific antigens. Three techniques that were used did not detect the presence of either hamster C-type particles or antigens commonly associated with such structures. The implication of these findings to current concepts of virus oncology is discussed.

Animals↗
PubMed1971

Synergistic effect of herpes simplex virus and cytosine arabinoside on human chromosomes.

The combined treatment of cultures of human embryonic lung cells with herpes simplex virus type 2 and cytosine arabinoside produced a significantly increased number of cells containing multiple chromatid and chromosome breaks. The incidence of such cells was found to be approximately two and one half times greater than the additive effects of virus and cytosine arabinoside induced separately and is therefore synergistic.

Autoradiography↗