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Biomedical subjects

R V Gilden

Publications and source records attributed to R V Gilden.

At least 19 recordsLinked to original sources
PubMed1979

Isolation and characterization of an endogenous type C virus of rhesus monkeys.

A type C retrovirus was isolated from a continuous cell line established from a spontaneous esophageal carcinoma of a rhesus monkey (Macaca mulata) by prolonged cocultivation with canine cells. A DNA transcript of the viral RNA hybridized to a high level and kinetic analysis indicated the presence of multiple copies of the viral genome in rhesus monkey DNA, showing that the virus is endogenous in this species. The rhesus monkey virus closely resembles, in several respects, an endogenous type C virus previously isolated from stumptailed macques (Macaca arctoides), aa species closely related to rhesus monkeys.

Animals↗
PubMed1979

Amino acid sequence homology between histone H5 and murine leukemia virus phosphoprotein p12.

The amino terminal acid sequences of several mouse leukemia virus phosphoproteins (p12) show definite homology with the amino terminal conserved region of H5 histones, the phosphorylated nuclear proteins of nucleated erythrocytes. Differences in the amino acid compositions of the two groups of proteins seem to rule out the possibility that they evolved from a single common ancestral gene. The finding of sequence homology between viral p12's and cellular histones, however, is consistent with evolution of retrovirus structural proteins by a process of differentiation from preexisting cellular genes. The conserved primary and secondary structure at the amino terminal region, common to both groups of proteins, may be related to their common function of nucleic acid binding modulated by phosphorylation.

Amino Acid Sequence↗
PubMed1979

Amino-terminal sequence of bovine leukemia virus major internal protein: homology with mammalian type C virus p30 structural proteins.

The amino acid composition, the COOH-terminal amino acid, and the NH2-terminal amino acid sequence of the first 55 residues of the major internal structural protein, p24, of bovine leukemia virus (BLV) were determined. The compositional data and the results of end-group analysis revealed that, although BLV p24 is chemically distinct, it more closely resembles the p30 structural proteins than the other gag gene products of mammalian retroviruses. It was found that BLV p24 shares the common NH2-terminal proline and COOH-terminal leucine but lacks the common prolylleucylarginine tripeptide and the larger conserved region found near the NH2 terminus of all mammalian type C viral p30s. Alignment of the amino acid sequence of BLV p24 with the previously determined sequence of feline leukemia virus p27 revealed a statistically significant sequence homology. A more distant relationship was found between BLV p24 and other mammalian p30s. The finding of a definite sequence homology between BLV p24 and mammalian type C virus p30s clearly establishes the origin of these contemporary viral proteins from common progenitor genes.

Amino Acid Sequence↗
PubMed1979

Reticuloendotheliosis virus: detection of immunological relationship to mammalian type C retroviruses.

Reticuloendotheliosis virus (REV) p30 shares cross-reactive determinants and a common NH2-terminal tripeptide with mammalian type C viral p30's. An interspecies competition radioimmunoassay was developed, using iodinated REV p30 and a broadly reactive antiserum to mammalian virus p30's. The avian leukosis-sarcoma viruses and mammalian non-type C retroviruses did not compete in this assay. Previous data indicating that the REV group is not represented completely in normal avian cell DNA lead us to speculate that this may be the first example of interclass transmission, albeit in the remote past, among the Retroviridae.

Animals↗
PubMed1979

An unlabeled antibody macromolecule technique using hemocyanin for the identification of type B and type C retrovirus envelope and cell surface antigens by correlative fluorescence, transmission electron, and scanning electron microscopy.

The present resolution (75-100 A) of the conventional scanning electron microscope (SEM) and its ability to image the surfaces of large numbers of whole cells in situ permit the approach of problems such as viral and cell surface antigen localization by immunological labeling with visual markers. Identification of virus and cell surface antigens in situ has been accomplished in indirect reactions by unconjugated markers. Hemocyanin (Hcy) from whelk, Busycon canniculatum, has been developed as an immunospecific marker for virion and cell surface labeling in the electron microscope. Its size (30 x 50 nm) and distinct cylindrical shape permit easy visualization in the SEM and the transmission electron microscope (TEM). The Hcy method involves the preparation of antisera to Hcy in appropriate hosts for use in an unlabeled antibody macromolecule procedure based exclusively on antigen-antibody affinity to couple the macromolecule to the antigen site. Further correlative data from fluorescence microscopy can be obtained from similarly labeled samples by binding fluorescein to the bridging antibodies used in the Hcy technique. The usefulness of the Hcy marker system was demonstrated by employing highly specific antisera to the major envelope and cell surface glycoprotein (gp70) of Rauscher murine leukemia virus (R-MuLV), a type C retrovirus. The antiserum was shown to bind to the virion and cell surfaces of virus-infected cells in the homologous virus-infected cell system. It also demonstrated the expression of R-MuLV gp70-related antigens on a murine cell line Mm5mt/c1 which produces mouse mammary tumor virus (MuMTV), a type B retrovirus. Furthermore, when used in the Hcy marker system the anti-gp70 serum was able to distinguish type B from type C budding virus on the same cell. Methods for the preparation of immunoreagents and labeling of cells are discussed.

Animals↗
PubMed1979

Prevention of spontaneous leukemia in AKR mice by passive immunization and type specificity of this protection.

AKR mice were given sc injections of goat antiviral immune globulin from birth through 14 or 31 days of age. Although the shorter immunization schedule greatly reduced expression of spontaneous leukemia, the longer immunization period was required for essentially complete prevention of leukemia. Immune globulin with a high neutralization titer for ecotropic virus provided this protection, whereas antibody with a high neutralization titer for murine xenotropic virus did not.

Animals↗
PubMed1979

Immunologic techniques for the identification of virion and cell surface antigens by correlative fluorescence, transmission electron and scanning electron microscopy.

The present resolution (75-100 A) of the conventional scanning electron microscope (SEM) and its ability to image the surfaces of large numbers of whole cells in situ permits the approach of problems such as viral and cell surface antigen localization by immunological labeling with visual markers. Identification of virus and cell surface antigens in situ has been accomplished in indirect reactions by conjugated and unconjugated markers. Hemocyanin (Hcy) from whelk, Busycon canniculatum, has been developed as an immunospecific marker for virion and cell surface labeling in the electron microscope. Its size (approximately 30 x 50 nm) and distinct cylindrical shape permit easy visualization in the SEM and TEM. The Hcy method involves the preparation of antisera to Hcy in appropriate hosts for use in an unlabeled antibody macromolecular procedure based exclusively on antigen-antibody affinity to couple the macromolecule to the antigen site. Further correlative data from fluorescence microscopy can be obtained from similarly labeled samples by binding fluorescein to the bridging antibodies used in the Hcy technique. The usefulness of the Hcy marker system was demonstrated using antisera to the major envelope and cell surface glycoprotein (gp70) of Rauscher murine leukemia virus (R-MuLV), a type C retrovirus. The antiserum was shown to bind to the virion and cell surfaces of virus-infected cells in the homologous virus-infected cell system. It also demonstrated the expression of R-MuLV gp70-related antigens on a murine cell line Mm5mt/c1 which produces mouse mammary tumor virus (MuMTV), A type B retrovirus. Furthermore, when used in the Hcy marker system this antiserum was able to distinguish type B from type C budding virus on the same cell. Examples of other marker systems (ferritin, peroxidase, colloidal gold, and latex) used to show anti-gp70 serum reactivity will be presented to demonstrate their applicability to cell surface labeling studies. Methods for the preparation of immunoreagents and labeling of cells are discussed.

Animals↗
PubMed1978

A portion of the feline leukaemia virus genome is not endogenous in cat cells.

Although viral sequences closely related to feline leukaemia virus are represented in multiple copies in cellular DNA of all domestic cats, a specific fraction was present only in the virus-infected cells. This fraction was detected by viral cDNA enriched by a prior absorption of a total complementary DNA (cDNA) transcript with normal cat liver DNA. The recycled cDNA hybridized well with the cellular DNA of virus-infected cells, but to a lesser extent with DNA from uninfected cat cells. The probe was used to differentiate virus-positive from virus-negative tumour tissues of cats. The same approach with cDNA of another endogenous feline virus, RD114, failed to show any difference between a virus-infected cell line and normal cells, including both virus-inducible and non-inducible lines.

Animals↗
PubMed1978

Search for infective mammalian type-C virus-related genes in the DNA of human sarcomas and leukemias.

DNA was extracted from two human sarcoma cell lines, TE-32 and TE-418, and the leukemic cells from five children with acute myelocytic leukemia, three children with acute lymphocytic leukemia and four adults with acute myelocytic leukemia. The DNAs, assayed for infectivity by transfection techniques, induced no measurable virus by methods which would detect known mammalian C-type antigens or RNA-directed DNA polymerase in TE-32, D-17 dog cells and other indicator cells, nor did they recombine with or rescue endogenous human or exogenous murine or baboon type-C virus. Model systems used as controls were human sarcoma cells, TE-32 and HT-1080, and human lymphoma cells TE-543, experimentally infected with KiMuLV, GaLV or baboon type-C virus, all of which released infectious virus and whose DNAs were infectious for TE-32 and D-17 dog cells. Other model systems included two baboon placentas and one embryonic cell strain spontaneously releasing infectious endogenous baboon virus and yielding DNAs infectious for D-17 dog cells but not for TE-32 cells. Four other baboon embryonic tissues and two embryonic cell strains, releasing either low levels of virus or no virus, did not yield infectious DNA.

Adult↗
PubMed1978

Amino- and carboxyl-terminal amino acid sequences of proteins coded by gag gene of murine leukemia virus.

The amino- and carboxyl-terminal amino acid sequences of proteins (p10, p12, p15, and p30) coded by the gag gene of Rauscher and AKR murine leukemia viruses were determined. Among these proteins, p15 from both viruses appears to have a blocked amino end. Proline was found to be the common NH(2) terminus of both p30s and both p12s, and alanine of both p10s. The amino-terminal sequences of p30s are identical, as are those of p10s, while the p12 sequences are clearly distinctive but also show substantial homology. The carboxyl-terminal amino acids of both viral p30s and p12s are leucine and phenylalanine, respectively. Rauscher leukemia virus p15 has tyrosine as the carboxyl terminus while AKR virus p15 has phenylalanine in this position. The compositional and sequence data provide definite chemical criteria for the identification of analogous gag gene products and for the comparison of viral proteins isolated in different laboratories. On the basis of amino acid sequences and the previously proposed H-p15-p12-p30-p10-COOH peptide sequence in the precursor polyprotein, a model for cleavage sites involved in the post-translational processing of the precursor coded for by the gag gene is proposed.

AKR murine leukemia virus↗
PubMed1978

Molecular mechanisms involved in the differential expression of gag gene products by clonal isolates of a primate sarcoma virus.

Clonal isolates of an early passage stock of woolly monkey sarcoma virus (WSV) have been shown to code for different numbers of woolly monkey helper leukemia virus gag gene products. In the present report, the molecular mechanisms responsible for their differential expression of gag gene products have been analyzed. Three WSV RNA genomes were shown to possess sedimentation coefficients consistent with the differences demonstrated in their allotments of helper viral sequences. The WSV variant (WSV clone 9) that expressed no detectable proteins was shown to contain the largest amount of helper viral information. Moreover, there was no additive hybridization of the WLV complementary DNA probe by RNA of this WSV clone and that of a WSV clone coding for several gag gene products. These results suggest that the lack of expression of gag gene products by WSV clone 9 is not due to a major deletion of helper viral gag gene sequences. Similar levels of WLV-specific RNA were demonstrated in cells nonproductively transformed by each WSV clone, arguing that the ability to express gag gene proteins was not related to the magnitude of viral RNA transcription. Taken together, the results are most consistent with a mechanism by which small deletions or point mutations in the genomes of some WSV variants result in premature termination of translation or synthesis of immunologically nonreactive gag gene proteins. The present findings have implications concerning the effects of evolutionary selective pressures on helper viral genetic information in mammalian transforming viruses.

Base Sequence↗
PubMed1978

Reiteration frequency of feline type C viral genomes in homologous and heterologous host cell DNA.

Differences in the multiplicity of proviral sequences of two feline endogenous viruses, RD-114 and FeLV, in homologous and heterologous host DNA were examined by viral cDNA hybridization using cellular DNA fractionated with respect to reiteration frequency. The endogenous proviral DNAs in cat cells were fractionated predominantly with intermediate-repeated sequences, while RD-114 proviral DNA in virus-infected human cells was fractionated together with unique-sequence DNA. These differences were consistent with the results of kinetic analysis using unfractionated DNA.

Animals↗
PubMed1978

Effects of hydroxyurea on murine type C virus-specific DNA synthesis in newly infected cells.

Cell transformation and replication of the Rauscher pseudotype of Moloney murine sarcoma virus in mouse embryo fibroblasts were inhibited by hydroxyurea within a critical time period of 30 to 90 min postinfection. In cells infected by Rauscher leukemia virus, treatment with 1mM hydroxyurea during the critical time period resulted in the accumulation of minus-strand DNA (molecular weight, 3 x 10(6)) in association with the parental viral genoma RNA. This 5 to 6 x 10(6) dalton RNA:DNA hybrid was found in the cytoplasm. Positive-strand DNA of genomic or smaller size was not detected in the presence of hydroxyurea, but virus-specific DNA was found in the nucleus 30 min after removal of drug.

Cell Transformation, Neoplastic↗