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Biomedical subjects

M S Reitz

Publications and source records attributed to M S Reitz.

At least 127 records · Page 7Linked to original sources
PubMed1982

Molecular cloning of circular unintegrated DNA of two types of the SEATO strain of gibbon ape leukemia virus.

Closed circular unintegrated DNA of the SEATO strain of gibbon ape leukemia virus (GaLV-S) was isolated from canine thymus fibroblasts after cocultivation with chronically infected bat lung fibroblasts. Restriction endonuclease HindIII cleaves GaLV-S DNA once, thus allowing isolation and cloning of HindIII-digested unintegrated DNA in a permitted form. Two clones isolated in the vector, Charon 21A, were nearly identical by restriction enzyme mapping to each of the two types of GaLV-S previously observed. These two types differ at a single SalI site. Unlike previous maps of GaLV-S proviral DNA, however, both clones lack SstI sites in the long-terminal-repeat units. Both the GaLV-S clones and the major species of GaLV-S proviral DNA contain an EcoRI site in the long-terminal-repeat units. The presence of this EcoRI site and the absence of an SstI site in the GaLV-S long-terminal-repeat units differentiate it from all other known GaLV strains and from the closely related nononcogenic simian sarcoma-associated virus. Heteroduplex comparisons of each of the two clones to clones of simian sarcoma-associated virus show no obvious deletion or substitution loops. This suggests that the ability of GaLV-S to induce myeloid leukemia in gibbon apes in not due to an acquired onc gene.

Animals↗
PubMed1981

Characterization and distribution of nucleic acid sequences of a novel type C retrovirus isolated from neoplastic human T lymphocytes.

A type C retrovirus (designated HTLV) recently isolated from a cell line derived from a lymph node and later from peripheral blood of a person with cutaneous T-cell lymphoma (mycosis fungoides) was characterized by nucleic acid hybridization experiments. HTLV [3H]cDNA hybridized 90% to its own 70S RNA with kinetics consistent with the genetic complexity of other retroviruses, but it did not hybridize substantially to RNA or proviral DNA from any animal retroviruses (types B, C, and D), including those from nonhuman primates. Conversely, [3H]cDNA from other retroviruses did not hybridize to RNA or DNA of the human T-cell line producing HTLV. HTLV proviral sequences were present (two to three copies per haploid genome) in DNA of these cells, and homologous sequences were present in the cell cytoplasmic RNA (0.3% viral sequences by weight). HTLV-related nucleic acid sequences were not found in DNA from various other human tissues. The results indicate that HTLV is a new class of type C virus that is not an endogenous (genetically transmitted) retrovirus in man.

Base Sequence↗
PubMed1981

Restricted expression of retrovirus nucleic acids and proteins in primate type C virus (gibbon ape leukemia virus-simian sarcoma virus)-initiated human B-lymphoblast cultures.

Fresh human B-lymphoblasts established in culture following exposure of adult peripheral blood leukocytes to type C retroviruses of the simian sarcoma virus/simian sarcoma-associated virus-gibbon ape leukemia virus group were analyzed in detail for the presence of the infecting virus. Viral expression ranged from production of low levels of intact virus in a few cultures to the presence of viral RNA and protein in the absence of detectable of levels of complete virus in the majority of the cultures. In situ molecular hybridization assays using 3H-labeled complementary DNA and indirect immunofluorescence assays using antibody to purified viral protein indicated that the expression of viral RNA and proteins are preferentially expressed in only a fraction of the cells in some cultures. If expression of the infecting viral sequences is necessary for the sustained growth of these cells, then those cells detectably synthesizing viral RNA and proteins may be influencing the growth of the remaining virus-negative cells. The lack of virus production in cultures synthesizing viral RNA and protein indicate that these human B-lymphocytes restrict the life cycle of these viruses at some step(s) after transcription of viral RNA or translation of viral protein.

B-Lymphocytes↗
PubMed1980

Isolation of a virus closely related to gibbon ape leukaemia virus from cells infected with virus (HL-23V) released by human leukaemic cells.

Canine thymus cells infected with virus (HL-23V) produced by human acute myelogenous leukaemia cells in culture were shown in previous reports to produce transforming and non-transforming type C virus similar or identical to the simian sarcoma virus complex SSV(SSAV) and to induce tumours in marmoset monkeys (Bergholz et al. 1977a). In these earlier studies the appearance of breakthrough foci at low dilutions of antiserum in neutralization tests with high-titred anti-SSV(SSAV) serum suggested the presence of another virus, distinct from SSV-(SSAV). We now report the isolation of this component and, by comparative neutralization analysis, demonstrate that it is most closely related to gibbon ape leukaemia virus (GALV). It is distinguished from SSV(SSAV) by kinetics of neutralization and molecular hybridization experiments. This component was readily cloned both from virus produced by HL-23V chronically-infected canine thymus cells established by Teich et al. (1975) when HL-23V was first isolated and from virus produced by HL-23V-induced marmoset tumour cells in culture. The presence of this component in the original leukaemic cell cultures is discussed.

Animals↗
PubMed1979

Characterization of a type-C virus produced by co-cultures of human leukemic bone-marrow and fetal canine thymus cells.

The putative human helper virus SKA-21/A204V, isolated by Nooter et al. in 1977 from human leukemic bone-marrow cells following co-culture with normal fetal canine thymus cells, Cf2th, has been characterized with respect to its major viral core protein, reverse transcriptase, and nucleic acid sequences. The results of these analyses show that this virus is not distinguishable from the woolly monkey type-C virus, SSAV-1, by the techniques employed.

Animals↗
PubMed1979

Retrovirus sequences in a leukemic gibbon and its contact: evidence for partial provirus in the nonleukemic gibbon.

Integrated viral DNA sequences were detected in tissues from two gibbon apes, a leukemic gibbon (6G-1) from whose leukocytes a distinct strain of gibbon ape leukemia virus (GaLVH) was isolated, and gibbon 6G-4, a contact of 6G-1 from the same colony that had uremia and cachexia of unknown origin. Although 6G-4 had no detectable neoplasia or viral proteins, its serum contained persistent antibody against GaLV antigens. Whereas DNA from most of the tissues of 6G-1 contained GaLV provirus, DNA from only three tissues (kidney, spleen, and liver) from 6G-4 showed detectable viral sequences, and the extent of hybridization in each case was lower than with 6G-1. After cleavage with BamHI, two virus-specific DNA fragments were detected in tissues of 6G-1. Only one of these fragments was detected in the positive tissues of 6G-4. The results indicate that: (i) 6G-4 was exposed to and infected by GaLV; (ii) early target sites for infection of gibbon by GaLV may be limited to a few tissues; and (iii) infection can be contained by integration of only partial provirus in a few tissues.

Animals↗
PubMed1979

Loss of proviral DNA sequences in a revertant of Kirsten sarcoma virus-transformed murine fibroblasts.

A previously described revertant cell line (K-BALB SR1212), derived as a single cell clone from a clonal line of murine fibroblasts (K-BALB) transformed by a nonproductive infection with the Kirsten strain of murine sarcoma virus, has normal morphology and growth kinetics and, unlike the transformed parent cell line, lacks a sarcoma virus that can be rescued. We report here that this reversion correlates with low to undetectable levels of expression of cellular Ki-MSV-specific RNA and a reduction of proviral sequences in the cell DNA to a level equivalent to that found in the uninfected BALB cells with a normal phenotype. The data indicate that phenotypic reversion has occurred as a consequence of the loss of part or all of the sarcoma provirus, either by chromosomal rearrangement or provirus excision.

Animals↗
PubMed1979

Gibbon ape leukemia virus-Hall's Island: new strain of gibbon ape leukemia virus.

Gibbon ape leukemia virus-Hall's Island (GaLV-H), a type C virus related to previous isolates of GaLV and simian sarcoma virus, was isolated from a gibbon ape with lymphocytic leukemia from a small colony of free-ranging gibbon apes on Hall's Island near Bermuda. We show here by molecular hybridization experiments that GaLV-H is approximately 60% related to three previous isolates of GaLV (GaLV-SF, GaLV-SEATO, and GaLV-Br) and is less closely related to simian sarcoma virus. The oligopyrimidine pattern of a transcript of the terminal 135 +/- 5 nucleotides of the viral RNA of GaLV-H is similar to that of GALV-Br but distinct from that of GaLV-SF and simian sarcoma virus. GaLV-H thus represents a fifth distinct strain of the infectious primate type C viruses, which among the previously described isolates of GaLV is most closely related to GaLV-Br.

Animals↗
PubMed1977

Lack of expression of type C hamster virus after neoplastic transformation of hamster embryo fibroblasts by benzo(a)pyrene.

Syrian hamster embryo fibroblasts transformed in vitro with benzo(a)pyrene were analyzed for the presence of type C viral components, including extra- and intracellular reverse transcriptase activity, intracellular type C hamster virus-related RNA, and cellular hamster virus group-specific antigen. No evidence could be obtained for the presence of any of these components, although they were easily detectable in hamster fibroblasts producing either B-34 virus (a hamster virus pseudotype of Harvey murine sarcoma virus which contains an excess of helper type C hamster virus) or Harvey virus itself. In addition, intracellular viral RNA could not be detected in normal hamster embryo fibroblasts, in hamster fibroblasts transformed with simian virus 40, or in newborn hamster kidney and liver. Thus the detectable expression of the indigenous hamster type C virus is not required to maintain the transformed phenotype of these cells.

Antigens, Viral↗
PubMed1976

Primate type-C virus nucleic acid sequences (woolly monkey and baboon types) in tissues from a patient with acute myelogenous leukemia and in viruses isolated from cultured cells of the same patient.

Cultured peripheral blood leukocytes from a woman (patient HL23) with acute myelogenous leukemia produced type-C RNA tumor viruses (HL23V). The viruses were analyzed by molecular hybridization experiments after transmission to five secondary cell culture lines. Using the criteria of molecular hybridization, we concluded that all of the transmitted virus isolates have nucleotide sequences related to the genome of simian sarcoma virus (SiSV). In addition, in agreement with data reported elsewhere, some of the transmitted viruses also have nucleotide sequences related to those of the baboon endogenous virus (BaEV). We also used molecular hybridization to ascertain whether both viruses could have originated from the patient HL23. Utilizing [3H] cDNA complementary to RNA from the separated BaEV-related component of HL23V and hybridizing this cDNA to DNA from tissues of the patient, we detected sequences related to BaEV in DNA obtained from the patient's spleen. These BaEV DNA sequences were also detectable when 125I-labeled RNA from BaEV was used as a probe. In agreement with earlier results, however, no SiSV-related sequences were detectable in the DNA of her tissues. Cytoplasmic viral-like particles, which had a buoyant density of 1.15-1.2 g/ml and were capable of synthesizing cDNA in association with a 35S RNA in vitro, were also found in the patient's fresh uncultured leukemic blood cells. cDNA synthesized by the cytoplasmic particles contained some sequences that hybridized to RNA from SiSV and, in addition, some that hybridized to RNA from BaEV. The cDNA also hybridized significantly to DNA isolated from the spleen of patient HL23 and to cytoplasmic RNA from the patient's leukocytes. These molecular hybridization results with nucleic acids obtained from the fresh blood cells of the patient, combined with the repeated isolation of similar viruses from different blood and bone marrow samples from the same patient, suggest that the virus come directly from the leukemic cell samples. The finding of BaEV-related DNA proviral sequences in the spleen of the patient strongly supports this interpretation. The failure so far to find a complete SiSV-related provirus is perplexing, but could be attributable to the existence of such a provirus in DNA of only a small population of cells in most leukemic patient.

Base Sequence↗
PubMed1975

Murine intracisternal type A particles: a biochemical characterization.

Intracisternal A particle preparations from a murine neuroblastoma cell line (N18) and from a mineral oil-induced murine plasmacytoma (MOPC-104E) contain both an endogenous RNA-dependent DNA polymerase activity and high molecular-weight polyadenylic acid (poly[A])-containing RNA. The DNA polymerase activity is stimulated by oligo(dG)-poly(C) and oligo(dT)-poly(A) and to a lesser extent by oligo(dT)-poly(dA), in agreement with previous reports. The high-molecular-weight RNA is predominantly 35S and contains a poly(A) tract of approximately 220 nucleotides as judged by polyacrylamide gel electrophoresis. Small amounts of 70S RNA are also present. This RNA preparation contains RNA homologous to RNA from type-C particles, as judged by molecular hybridization experiments. However, since this RNA derives only in part from A-particles and in part from other cellular RNA, hybridization of A-particle endogenously synthesized DNA or reverse transcripts of A-particle RNA to purified type C viral 70S RNA may more accurately reflect the relationship of A-particle RNA to RNA from C-particles. None of these DNA transcripts hybridizes significantly to C-particle 70S RNA, although MOPC and N18 DNA transcripts share significant homology. Our interpretation of these results is that murine intracisternal A particles are not closely related genetically to the tested murine type C viruses, although an alternate possibility is that all the A-particle DNA transcripts are copied from only a small part of the genome, which is unrelated to C-particle RNA.

Base Sequence↗