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L F Lee

Publications and source records attributed to L F Lee.

At least 91 records · Page 5Linked to original sources
PubMed1976

Characteristics of JMV Marek's disease tumor: a nonproductively infected transplantable cell lacking in rescuable Virus.

Cells of the JMV Marek's disease (MD) tumor, originally produced by rapid serial passage of MD lymphoma cells in chickens, were characterized to determine whether they were of host or donor origin and to ascertain certain virus-host cell interrelationships. Differences noted in blood group B surface alloantigens between tumor cells and host lymphocytes indicated a probable nonhost origin (i.e., transplantability) of the tumor. JMV spleen tumors contained predominantly large lymphoblasts bearing MD tumor-associated surface antigen. DNA from JMV tumor cell suspensions hybridized significantly with MD virus cRNA, which indicated that JMV cells contained at least a portion of the MD virus genome. No MD virus was rescued from JMV tumors by techniques suitable for rescue of virus from MD lymphomas. The JMV tumor cells were also devoid of MD virus-specific antigens. These properties differed markedly from those of MD lymphoma cells and make the JMV tumor cell a unique, potentially valuable, tool for further study of oncogenic herpesvirus infection and tumor immunity in the chicken.

ABO Blood-Group System↗
PubMed1975

Oncogenesis by Marek's disease herpesvirus in chickens lacking expression of endogenous (gs, chick helper factor, Rous-associated virus-O) and exogenous avian RNA tumor viruses.

Chickens free of exogenous avian leukosis virus (ALV) infection, replicating endogenous ALV (Rous-associated virus-O), gs antigen, and chick helper factor were fully susceptible to induction of Marek's disease (MD) by ALV-free MD viruses. Dual infection with Rous-associated virus-2 and MD virus did not significantly alter the character of the MD lesions. Thus exogenous ALV infection was not requisite for MD virus-induced oncogenesis. Although participation of endogenous RNA tumor virus genes in MD lesion induction could not be excluded, expression of such genes in MD tumors as gs antigen was not established.

Animals↗
PubMed1974

Marek's disease herpesvirus-induced DNA polymerase.

Infection of duck embryo fibroblasts by Marek's disease herpesvirus (MDHV), strain GA, led to the induction of a novel DNA polymerase. This novel DNA polymerase, designated MDHV-induced DNA polymerase, could be distinguished from the DNA polymerase activities of uninfected duck embryo fibroblasts by its chromatographic behavior on phosphocellulose, by its sedimentation coefficient, and by its catalytic properties. The characteristics of MDHV-induced DNA polymerase which had been purified by phosphocellulose chromatography were investigated. The sedimentation coefficient of the enzyme, as determined by sucrose density gradient centrifugation in the presence of 0.25 M KCl, was 5.9S. From this sedimentation coefficient, the molecular weight of MDHV-induced DNA polymerase was estimated to be 100,000. MDHV-induced DNA polymerase could not effectively use either poly(dA).oligo(dT)(12-18) or poly(dC).oligo(dG)(12-18) as a template-primer. The DNA polymerases from uninfected duck embryo fibroblasts could use these synthetic template-primers. MDHV-induced DNA polymerase also could not use poly(rA).oligo(dT)(12-18) or poly(rC).oligo(dG)(12-18) as template-primers or oligo(dT)(12-18) as a primer, indicating that it was not a polymerase of the type R-DNA polymerase, reverse transcriptase, or a terminal nucleotidyl transferase. In vitro synthesis of DNA by MDHV-induced DNA polymerase was markedly inhibited by the addition of (NH(4))(2)SO(4) to the reaction mixture.

Ammonium Sulfate↗
PubMed1973

Deoxyribonucleic acid of Marek's disease virus in virus-induced tumors.

DNA was extracted from [(3)H]thymidine-labeled Marek's disease virus (MDV) and purified by two cycles of CsCl gradient centrifugation in a fixed-angle rotor. The DNA was transcribed in vitro into (32)P-labeled complementary RNA (cRNA). MDV cRNA did not hybridize with DNA from chicken embryo fibroblast cultures or from chicken spleen, but hybridized efficiently with DNA from MDV particles or MDV-infected cell cultures. Five Marek's disease tumors from different chickens and different organs (ovary, liver, testis) were all found to contain MDV DNA sequences. The relative amount of MDV DNA varied from tumor to tumor and was between 3 and 15 virus genome equivalents per cell. The content of virus DNA per cell in spleens from tumor-bearing chickens was much lower than in tumors from the same animals. MDV-infected cell cultures contained a large proportion (28-59%) of virus antigen-positive cells, as measured by immunofluorescence, but tumor cells were negative in this respect (<0.02% positive cells). These data indicate that MDV is present in a provirus form in tumor cells.

Animals↗
PubMed1972

Induction of deoxyribonucleic acid synthesis and the oncogenicity of Marek's disease virus.

Leukocytes recovered from birds inoculated with an oncogenic strain of Marek's disease virus synthesized deoxyribonucleic acid in vitro at a rate 7.9 times that of leukocytes from normal birds or birds inoculated with the nononcogenic herpesvirus of turkeys. A close relationship was observed between the level of in vitro deoxyribonucleic acid synthesis and in vivo tumor formation.

Animals↗
PubMed1971

Size and composition of Marek's disease virus deoxyribonucleic acid.

Deoxyribonucleic acid (DNA) extracted from purified nucleocapsids of Marek's disease herpesvirus (MDV) was cosedimented with T4 and with herpes simplex virus (HSV) DNA in neutral sucrose density gradients and with T4 DNA in alkaline sucrose density gradients. These experiments indicated that the intact MDV DNA had a sedimentation constant of 56S corresponding to a molecular weight of 1.2 x 10(8) daltons. In the alkaline gradients, the largest and most prominent band contains a DNA sedimenting at 70S corresponding to 6.0 x 10(7) daltons in molecular weight. The DNA is therefore double-stranded and not cross-linked. Isopycnic sedimentation of the MDV DNA molecules with SPO1, Micrococcus lysodeikticus, and HSV DNA gave a density of 1.705 g/cm(3) corresponding to 46 guanine plus cytosine moles per cent. Lastly, in hybridization tests the DNA hybridized with RNA of infected cells but not with that of uninfected cells supporting the conclusion that it is viral.

Alpharetrovirus↗
PubMed1969

Marek's disease herpes virus: a cytomegalovirus.

The DNA of herpes viruses associated with Marek's disease of fowl contains 56-57 moles of guanine and cytosine per 100. The composition of its DNA and lack of infectiousness of cell-free preparations suggest that the herpes virus associated with Marek's disease belongs to the herpes virus group B which contains predominantly cytomegaloviruses.

Animals↗