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At least 19 recordsLinked to original sources
PubMed1962

The biological, immunological, and physicochemical characterization of a transmissible agent capable of inducing DNA and thymine degradation in cultured human cells.

EXPERIMENTS DESIGNED TO CHARACTERIZE AN UNIDENTIFIED TRANSMISSIBLE AGENT BROUGHT FORTH THE FOLLOWING FINDINGS: The cytopathology consisted of the formation of intranuclear globules, collapse of the involved nuclei, and the extrusion of nuclear materials. The relatively dormant primary human amnion cells were less susceptible than the rapidly growing cell lines. Similarly, the slowly multiplying ribose variants were less susceptible than their corresponding parent cell lines. Interferon-like activity was released from infected cells. Infectivity was readily demonstrated following storage at 0-4 degrees C for at least 8 months or at 37 degrees C for at least 2 weeks. Freeze-thawing, however, markedly reduced or completely destroyed its infectivity. Infectivity was destroyed completely by ether and chloroform; partially by desoxycholate, and not affected by trypsin, papain, RNAse, DNAse, hyaluronidase, lysozyme, lecithinase, or pancreatic lipase. The rate of inactivation by 0.025 per cent formalin was much slower than that of vaccinia and herpes viruses. Its synthesis was suppressed by 5-fluorodeoxyuridine. This suppression was not reversed by thymidine and/or uracil. Heat-stable neutralizing antibody could not be demonstrated in 379 human and animal serums, in human gamma globulins, or in serums from animals "immunized" with this agent. Heat-labile inhibitors (lipoprotein-like) capable of inhibiting the infectivity of this agent were demonstrated in 154 of the 157 serums tested. Experimental evidence indicated the non-identity of this ubiquitous inhibitor and the properdin system. The non-infectious complex between this agent and the ubiquitous serum inhibitor may be dissociated (hence, become infectious) by simple dilution. Repeated attempts to reisolate a similar agent have not been successful. We have hypothesized that this agent is a virus consisting of DNA wrapped in a surface coat rich in lipid, and suggest that this virus be referred to tentatively as a lipovirus.

Animals↗
PubMed1962

A study of the mechanisms of DNA And thymine degradation in cultured human cells infected with a lipovirus.

DNA and thymine degradation on cultured human, mouse, and chick cells were studied. Significant increase in DNA-degrading activity was demonstrated in human embryonic cells killed by freeze-thawing, liver cells killed with mitomycin C, mouse embryonic cells infected with encephalomyocarditis virus, and in all cells killed by the lipovirus. Twelve other viral agents, actinomycin D, and 5-fluorodeoxyuridine failed to produce a similar increase. Thymidine-2-C(14)-labeled cultures, either live, killed, or infected by 19 different physical-chemical and biological agents, did not release detectable quantity of C(14)C(2). Following infection with the lipovirus 20 to 60 per cent of the total radioactivity of thymidine-2-C(14)-labeled cultures was liberated as C(14)O(2). It was postulated that the lipovirus introduced into the host cells the missing genetic information necessary for the synthesis of one or more enzymes responsible for the reductive catabolism of thymine.

Animals↗