Harish C. Chopra

Spontaneous Transformation of Human Brain Cells Grown in vitro and Description of Associated Virus Particles

A human brain cell culture grown in vitro has spontaneously transformed, as determined by morphology, growth characteristics, and karyotype analysis. Virus particles morphologically akin to oncogenic RNA viruses are present in the transformed cells, which are now in subculture 60.

Characteristics ofHerpesvirus saimiri-induced lymphoma cells in tissue culture

SummaryLymphoblastoid cells were cultured from twoHerpesvirus saimiri (HVS) inoculated white-lipped marmosets and from one HVS-inoculated owl monkey. Cells from all three animals grew clumped in suspension. The cells from both species were diploid in chromo-some number and showed no unusual chromosomal abnormalities. The marmoset cell line examined was chimaeric. The marmoset cells lacked HSV-associated antigens as determined by immunofluorescence, and no evidence for the presence of virus was found by either infectivity assays or electron microscopy. Cocultivation of these cells with Vero cells resulted in cytopathology and the recovery of complete, infectious virus. The owl monkey lymphoid cells were positive to a small degree for both viral antigens and infectivity. The cells were resistant to rechallenge with HVS. Cocultivation of these cells with Vero cells led to the development of cytopathology and an increased yield of virus.

Discussion from an article titled studies on the possible viral etiology of human breast cancer

must be present shortly after birth to be effective. It is equally infectious if given orally or by a parenteral route. The development of a mammary malig nancy in a mouse takes approximately 10 months or one half of the usual life-span of the mouse. The malignant transformationisconditionedby three distinct factors: (1) the presence of the virus; (2) the “¿ hormonal milieu― of the animal; and (3) the genetic constitution of the animal. Investigative effort aimed at under standing the exact interrelationship of these three factors is being carried on in a number of laboratories through out the world. Recent work has sug gested that estrogens acting at the cellular level may activate specific genes in the normal mammary epi thelial cells. The cancer virus may in teract with these “¿ activated genes―or their RNA complements to effect a malignant transformation. It is becom ing increasingly evident that a satis factory description of the manner in which the mouse mammary tumor virus produces cancer must depend upon a demonstrable interaction between an RNA virus and a steroid hormone molecule. This virus has been shown under the electron microscope to resemble the influenza virus. Electron micro scopic studies have shown the virus to be present in normal secreting mam mary epithelium, in preneoplastic tissue, and also in the tumor cell itself. The presence of the virus in a mouse cell does not necessarily indicate that the cell is malignant. Biochemical studies on purified preparations have revealed that the virus particle is a lipid-rich particle and contains ap proximately 0.8 per cent ribonucleic acid. It is the RNA which accounts for the essential activity of the virus. The ribonucleic acid is believed to be of a single-strand character. Discussion from an article titled Studies on the Possible Viral Etiology of Human Breast Can cer, by William F. Feller, M.D., Ph.D., Harish Chopra, Ph.D., and Frank Bepko, M.D.