Eckert, Edward A. (University of Michigan, Ann Arbor). Envelope protein(s) derived from influenza virus. J. Bacteriol. 91: 1907–1910. 1966.—Lipids were extracted from influenza virus, strain PR8, with methanol-chloroform, and the protein residue was dissolved in 67% glacial acetic acid. Hemagglutinating activity and complement-fixing reactivity were markedly reduced or lost during lipid extraction, and then increased after acetic acid treatment and subsequent dialysis. Evidence is presented that the envelope protein(s) responsible for these activities is dissociated in acetic acid and reassociated at neutral p H.

Homogeneous preparations of rubella complement fixing antigen, in sufficient quantity for routine serological work, have been obtained from the fluid phase of infected tissue cultures. Filtration experiments have demonstrated that at least part of the anti-genic activity is due to units smaller than the virus particles. Additional experiments on purification and characterization of this material are in progress. Complement fixing antibodies appear slowly after infection, reaching their peak titers by the third to sixth month, and persist with only a slight decrease a year after the acute episode.

Journal Article Virus of Avian Erythroblastosis. I. Titration of Infectivity Get access Edward A. Eckert, Edward A. Eckert Department of Surgery, Duke University School of Medicine, Durham, N. C. Search for other works by this author on: Oxford Academic PubMed Google Scholar Dorothy Beard, Dorothy Beard Department of Surgery, Duke University School of Medicine, Durham, N. C. Search for other works by this author on: Oxford Academic PubMed Google Scholar J. W. Beard J. W. Beard Department of Surgery, Duke University School of Medicine, Durham, N. C. Search for other works by this author on: Oxford Academic PubMed Google Scholar JNCI: Journal of the National Cancer Institute, Volume 16, Issue 5, April 1956, Pages 1099–1120, https://doi.org/10.1093/jnci/16.5.1099 Published: 01 April 1956 Article history Received: 20 September 1955 Published: 01 April 1956

Chickens have been hyper immunized with formolized concentrates of the virus of avian erythromyeloblastic leukosis together with the untreated plasma of diseased birds containing the agent in high concentration. The resulting immune serums strongly neutralized the infectious properties of the virus and precipitated the characteristic virus particles as observed macroscopically and corroborated by electron micrographs of the precipitates. Precipitation of the virus particles was associated with proportional precipitation of the enzyme activity of the virus to dephosphorylate adenosine triphosphate. The findings constitute the critical specific criterion needed to establish the particles as the virus and the enzyme as a component inseparable, by all methods yet tried, from these virus particles.

Virus of Avian Erythromyeloblastic Leukosis. VII. Thermal Stability of Virus Infectivity; of the Virus Particle; and of the Enzyme Dephosphorylating Adenosinetriphosphate Get access Edward A. Eckert, Edward A. Eckert Department of Surgery, Duke University School of Medicine, Durham, N.C. Search for other works by this author on: Oxford Academic PubMed Google Scholar Irving Green, Irving Green Department of Surgery, Duke University School of Medicine, Durham, N.C. Search for other works by this author on: Oxford Academic PubMed Google Scholar D. G. Sharp, D. G. Sharp Department of Surgery, Duke University School of Medicine, Durham, N.C. Search for other works by this author on: Oxford Academic PubMed Google Scholar Dorothy Beard, Dorothy Beard Department of Surgery, Duke University School of Medicine, Durham, N.C. Search for other works by this author on: Oxford Academic PubMed Google Scholar J. W. Beard J. W. Beard Department of Surgery, Duke University School of Medicine, Durham, N.C. Search for other works by this author on: Oxford Academic PubMed Google Scholar JNCI: Journal of the National Cancer Institute, Volume 16, Issue 1, August 1955, Pages 153–161, https://doi.org/10.1093/jnci/16.1.153 Published: 01 August 1955 Article history Received: 03 February 1955 Published: 01 August 1955

A new era of interest in viruses as potential carcinogens was introduced by the work of Rous and his co-workers in the demonstration of the tumor attributes of the virus-induced Rabbit Papilloma, and the observation of the progression of the growth to outright carcinoma. Full appreciation of the import of these studies of a mammalian virus tumor might have been retarded had it not been for the timely recognition of the viral etiology of mouse mammary carcinoma. Here was a growth conceded to be exemplary of mammalian cancer and intensively studied for many years as a typical tumor. Among the many problems of the virus tumors, there is none more critical than the nature and properties of the essential causative agents. At least two remarkably different tumor viruses, the agent of the rabbit papilloma and that of avian erythromyeloblastica leukosis, have been obtained in the preparations of purity and the amount sufficient for quantitative characterization. The experimental data provides a foundation not only with respect to knowledge of the properties of these agents but for quantitative clarification of many questions of known host-virus relations not susceptible to final resolution except by the study of the isolated viruses. The status of the problem of the virus of mouse mammary carcinoma has been reviewed recently by Dmochowski and that of the chicken sarcoma by Claude and Murphy, Foulds, Duran-Reynals, and Harris. It is the purpose of this chapter to discuss the physico-chemical findings derived through the study of the purified papilloma and erythromyeloblastic leukosis viruses and their application to the interpretation of certain biological phenomena associated with the growths that they cause. This chapter also considers some of the implications of these findings with respect to virus diseases in general.

Virus of Avian Erythromyeloblastic Leukosis. IX. Antigenic Constitution and Immunologic Characterization Get access Edward A. Eckert, Edward A. Eckert Department of Surgery, Duke University School of Medicine, Durham, N. C. Search for other works by this author on: Oxford Academic PubMed Google Scholar D. G. Sharp, D. G. Sharp Department of Surgery, Duke University School of Medicine, Durham, N. C. Search for other works by this author on: Oxford Academic PubMed Google Scholar Dorothy Beard, Dorothy Beard Department of Surgery, Duke University School of Medicine, Durham, N. C. Search for other works by this author on: Oxford Academic PubMed Google Scholar Irving Green, Irving Green Department of Surgery, Duke University School of Medicine, Durham, N. C. Search for other works by this author on: Oxford Academic PubMed Google Scholar J. W. Beard J. W. Beard Department of Surgery, Duke University School of Medicine, Durham, N. C. Search for other works by this author on: Oxford Academic PubMed Google Scholar JNCI: Journal of the National Cancer Institute, Volume 16, Issue 3, December 1955, Pages 593–643, https://doi.org/10.1093/jnci/16.3.593 Published: 01 December 1955 Article history Received: 09 May 1955 Published: 01 December 1955

Journal Article Virus of Avian Erythromyeloblastic Leukosis. V. pH Stability of the Virus Particles, the Infectivity and the Enzyme Dephosphorylating Adenosine Triphosphate Get access Edward A. Eckert, Edward A. Eckert Department of Surgery, Duke University School of Medicine, Durham, N. C. Search for other works by this author on: Oxford Academic PubMed Google Scholar Irving Green, Irving Green Department of Surgery, Duke University School of Medicine, Durham, N. C. Search for other works by this author on: Oxford Academic PubMed Google Scholar D. G. Sharp, D. G. Sharp Department of Surgery, Duke University School of Medicine, Durham, N. C. Search for other works by this author on: Oxford Academic PubMed Google Scholar Dorothy Beard, Dorothy Beard Department of Surgery, Duke University School of Medicine, Durham, N. C. Search for other works by this author on: Oxford Academic PubMed Google Scholar J. W. Beard J. W. Beard Department of Surgery, Duke University School of Medicine, Durham, N. C. Search for other works by this author on: Oxford Academic PubMed Google Scholar JNCI: Journal of the National Cancer Institute, Volume 15, Issue 5, April 1955, Pages 1209–1215, https://doi.org/10.1093/jnci/15.5.1209 Published: 01 April 1955 Article history Received: 13 September 1954 Published: 01 April 1955

Changes have been made in the conditions of the micro test of plasmas from chicks with erythromyeloblastic leukosis for their capacity to dephosphorylate adenosine triphosphate. The principal modification has involved use of a balanced saline solution in the reaction mixture resulting in a very large increase in the precision, sensitivity and resolution of the procedure. With 3-λ of plasma, instead of the 5-λ volumes employed earlier, the expected error of a single determination in 2 of 3 cases is ±4 gamma phosphorus on the basis of measurements by electrometric titration. The greater sensitivity has extended the range of plasma activity possible for accurate measurement and has shortened the time necessary for the estimation.

The equipment and the procedures have been devised for quantitative complement fixation in volumes of 12 mm3. The technic, reduced to a routine basis, is illustrated in the results obtained in the titration of complement and in the estimation of complement fixed by pneumococcus polysaccharide type VIII and its specific antiserum induced in the rabbit. With the procedures described the reaction can be carried out with antigen and antiserum in amounts of the order of 100-fold less than those required for the volumes usually employed, greatly extending the range for the study of material available only in small quantities.

A particulate material has been obtained from the plasma of chickens affected with the RPL 12 lymphoid tumor strain. Electron micrographs of the particles sedi-mented directly from plasma and of those in ultracentrifugal concentrates reveal spherical or spheroidal particles of sizes varying from 70 to 160 mμ in diameter and an average diameter of about 117 mμ. Particle counts on the individual plasmas of birds with advanced disease gave values of 1 × 107 to 160 × 107 particles per ml in contrast with the normal plasmas in which only occasional or no particles of this size range were observed. The findings with this form of the leukosis complex are remarkably similar to the results of analogous studies on erythromyeloblastic leucosis. The particles seen in the present work are interpreted, tentatively, as representing the virus of one form of avian lymphomatiosis.

In a recent report (Beard et al., 1950) there were described briefly the isolation and some of the characters of a particulate component from the plasma of chickens affected with erythro-myeloblastic leucosis. Continued study of the material has resulted in slowly accumulating evidence suggesting the identity of the component with the viral etiologic agent of the disease. Electron micrographs of the component isolated by ultracentrifugal procedures revealed a population of particles apparently of considerable homogeneity with respect to kind but of variable size and shape. In the preliminary studies, it was evident that the morphologic character of the particles was greatly influenced by various factors, certain of which were encountered in the technical procedures for preparing the material for electron micrography. Consequently, an investigation has been made of the component under various conditions with the object of learning, ultimately, the character of the virus as it exists naturally in the circulating blood plasma. The results of this work and a comparison of the findings with leucosis virus with those of the virus of Newcastle disease, which it resembles in morphology, are described in the present paper.

A highly potent capacity for the dephosphorylation of adenosine triphosphate has been observed with preparations containing the virus of avian erythromyeloblastic leucosis. This enzymatic reaction occurred with the filtered plasma of birds diseased with the virus and with virus concentrates obtained from the plasma by ultracentrifugal procedures. The partition of enzymatic activity in these preparations has closely paralleled the distribution of virus infectivity of analogous materials measured in other work by titration of the virus in susceptible host chicks. No evidence of the reaction was obtained with the plasma from normal chickens. These experiments demonstrate the specific relationship of the dephosphorylation of adenosine triphosphate with avian erythromyeloblastic leucosis and indicate that the activity is a property of the etiological virus.

Journal Article Variation in Infectivity and Virus-Particle Content of Individual Plasmas from Birds with Erythromyeloblastic Leukosis Get access Edward A. Eckert, Edward A. Eckert Department of Surgery, Duke University School of Medicine, Durham, N. C. Search for other works by this author on: Oxford Academic PubMed Google Scholar D. G. Sharp, D. G. Sharp Department of Surgery, Duke University School of Medicine, Durham, N. C. Search for other works by this author on: Oxford Academic PubMed Google Scholar Dorothy Beard, Dorothy Beard Department of Surgery, Duke University School of Medicine, Durham, N. C. Search for other works by this author on: Oxford Academic PubMed Google Scholar J. W. Beard J. W. Beard Department of Surgery, Duke University School of Medicine, Durham, N. C. Search for other works by this author on: Oxford Academic PubMed Google Scholar JNCI: Journal of the National Cancer Institute, Volume 13, Issue 2, October 1952, Pages 533–542, https://doi.org/10.1093/jnci/13.2.533 Published: 01 October 1952 Article history Received: 16 June 1952 Published: 01 October 1952