Replication of the reticuloendotheliosis virus (strain T) in chicken embryo cell culture

Investigations were conducted on the in vitro replication of the reticuloendotheliosis (RE) virus (strain T) in specific-pathogen-free chicken embryo fibroblast (CEF) cultures. Active virus production was detected in the tissue culture fluid 24 hr after infection. When injected into chickens, samples taken 42 hr after infection of the cell cultures killed approximately 50% of the birds at a 1:100 dilution. The RE virus titer remained at this level for 5 days before declining. Cell-free virus preparations from tissue cultures rarely resulted in 100% mortality of the assay birds. The level of cell-associated virus was very low. Evidence that the reticuloendotheliosis was not induced by a mycoplasma was indicated by failure to isolate an organism on PPLO Agar (Difco) and failure of kanamycin or amphotericin B to inhibit multiplication of RE virus in vitro. RE virus appeared to be unrelated to members of the avian leukosis and sarcoma complex. It did not induce resistance in CEF cultures to sarcoma viruses of the A or B subgroup of this complex. Similarly, preinfection of cell cultures with leukosis viruses of the A or B subgroup did not inhibit or reduce the replication of RE virus.

Dating and Authenticating Works of Art by Measurement of Natural Alpha Emitters

A method for distinguishing between modern and old samples of lead has been used to analyze certain works of art. The basis of the method is the detection of radioactive lead-210, which decays with a 22-year half-life when it is unsupported by its long-lived precursor, radium-226. The latter is separated chemically from lead when lead and lead products are prepared from the ore.

Selective response of the Japanese quail to various strains of Rous sarcoma virus

Shipman, Charles Jr. (Indiana University School of Medicine, Indianapolis), and Alvin S. Levine. Selective response of the Japanese quail to various strains of Rous sarcoma virus. J. Bacteriol. 92:161-163. 1966.-The Bryan "high-titer," Carr-Zilber, Harris, Prague, Schmidt-Ruppin, and "29" strains of Rous sarcoma virus were used to initiate tumors in the Japanese quail (Coturnix coturnix japonica). Although all strains produced tumors upon primary inoculation, only the Bryan "high-titer" and Harris strains could be serially passaged with cell-free tumor extracts. Analysis by means of the end-point dilution technique and the interference test revealed that the tumor extract of the Bryan "high-titer" strain passaged 10 times in the quail contained a Rous-associated virus.

Effects of ribonuclease and deoxyribonuclease on a murine leukemia virus (Rauscher)

Plasma pellets and femoral bone marrow from BALB/cJ mice infected with the Rauscher leukemia virus were fixed, embedded, and sectioned. The thin sections were incubated in ribonuclease and deoxyribonuclease solutions, stained, and examined in the electron microscope. Specific attention was paid to the action of the nucleases on characteristic virus particles in the plasma preparations and on viruses being produced by the "budding" phenomenon in the femoral bone marrow. Ribonuclease solutions digested the nucleoids of the virus particles in the plasma preparations from mice infected with Rauscher leukemia virus. The nucleoid portion of the "budding" virus particles in bone marrow, and the connecting cytoplasm of the stalks were also digested by ribonuclease solutions. In addition, the outer coat of the "budding" particles was affected in a nonspecific manner. The centers of the "budding" particles in the bone marrow and the nucleoids of viruses in plasma preparations were not digested by deoxyribonuclease solutions. Influenza virus, a known ribonucleic acid (RNA) virus, was used as a control for nuclease activity. The nucleoids of influenza virus particles were digested by ribonuclease but not by deoxyribonuclease solutions. After coriphosphine staining of the plasma virus preparations, the fluorescence was quenched in preparations treated with ribonuclease, but did not appear to be diminished in those treated with deoxyribonuclease. This study suggests that infection of mice with Rauscher leukemia virus produces virus particles in plasma and "budding" particles in bone marrow, both of which contain RNA.