Journal of virology
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Journal of virology · Dec 1993
Comparative StudyThe cell surface receptor is a major determinant restricting the host range of the B-lymphotropic papovavirus.
The B-lymphotropic papovavirus (LPV) productively infects only a subset of human B-lymphoma-derived cell lines while transfection of the viral genome yields infectious viral particles in a much wider variety of human hematopoietic cell lines. We have analyzed the contribution of a putative LPV receptor on the cell surface of B-cell lines in restricting the virus host range. In order to establish a quantitative virus binding assay for LPV, infectious virus particles were highly purified by metrizamide equilibrium density centrifugation and used as immunogens to raise seven mouse monoclonal antibodies specific for LPV VP1. ⋯ Reduction of LPV binding to sialidase-pretreated BJA-B cells was accompanied by a similar reduction of infection, indicating that virus binding may be a limiting factor in the LPV replicative cycle. The two highly LPV-permissive human B-lymphoma cell lines BJA-B and Namalwa displayed high virus binding whereas low and nonpermissive hematopoietic cell lines showed reduced or undetectable virus binding. We conclude that the inability of LPV particles to productively infect the nonpermissive human hematopoietic cell lines analyzed is probably due to the absence or insufficient expression of a functional cell surface receptor.
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Journal of virology · Jan 1993
Comparative StudyBorna disease virus in mice: host-specific differences in disease expression.
We developed a mouse model of Borna disease to facilitate immunopathogenesis research by adaptation of Borna disease virus to mice through serial passage in mouse brain tissue. Borna disease virus replication, antibody production, inflammation, and Borna disease expression in several different strains of mice were examined.
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Journal of virology · Oct 1981
Simian virus 40 early mRNA's contain multiple 5' termini upstream and downstream from a Hogness-Goldberg sequence; a shift in 5' termini during the lytic cycle is mediated by large T antigen.
We have used primer-directed synthesis, separation, and sequencing of cDNA's to identify and localize the 5' termini of simian virus 40 early mRNA's. We have examined polyadenylated RNAs obtained from whole cytoplasm and polysomes of two transformed lines and from the cytoplasm of infected cells early and late in the lytic cycle, and we have attempted to correlate the results of our cDNA analyses with recent analyses of early cap structures. We have found that early mRNA's from transformed cells have three principal 5' termini, at residues 5,150, 5,154, and 5,155, with terminal transcribed sequences of CU, GC, and GG, respectively. ⋯ We present two models, which are mutually exclusive, to account for the role of T antigen in the early-late shift. One involves transcription late in infection on a new DNA template synthesized during DNA replication. The second involves inhibition of initiation of early transcription at residues 5,150 to 5,155 and other downstream sites and a shift of transcription initiation principally to the upstream sites as a result of the binding of T antigen to two sites on simian virus 40 DNA downstream from the Hogness-Goldberg sequence.
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Agarose gel electrophoresis of the following was performed in 0.05 M sodium phosphate-0.001 M MgCl2 (pH 7.4): (i) bacteriophage T7; (ii) a T7 precursor capsid (capsid I), isolated from T7-infected Escherichia coli, which has a thicker and less angular envelope than bacteriophage T7; (iii) a second capsid (capsid II), isolated from T7-infected E. coli, which has a bacteriophage-like envelope; and (iv) capsids (capsid IV) produced by temperature shock of bacteriophage T7. Bacteriophage T7 and all of the above capsids migrated towards the anode. In a 0.9% agarose gel, capsid I had an electrophoretic mobility of 9.1 +/- 0.4 X 10(-5) cm2/V.s; bacteriophage T7 migrated 0.31 +/- 0.02 times as fast as capsid I. ⋯ To increase the accuracy of mobility comparisons and to increase the number of samples that could be simultaneously analyzed, multisample horizontal slab gels were used. Treatment with the ionic detergent sodium dodecyl sulfate converted capsid I to a capsid that migated in the capsid II region during electrophoresis through agarose gels. In the electron microscope, most of the envelopes of these latter capsids resembled the capsid II envelope, but some envelope regions were thicker than the capsid II envelope.
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Journal of virology · Oct 1978
Comparative StudyTwo initiation sites for translation of poliovirus RNA in vitro: comparison of LSc and Mahoney strains.
Previous studies in our laboratory provided evidence that the initiation of translation by the Mahoney strain of poliovirus type 1 RNA in vitro occurs at two unique sites. This study shows that the LSc strain of poliovirus type 1, a multistep, temperature-sensitive mutant of the Mahoney strain, also utilizes two sites for the initiation of translation in vitro. ⋯ The polypeptides containing amino-terminal label showed similar patterns on sodium dodecyl sulfate-acrylamide gels, although one of the LSc polypeptides had a slightly faster mobility. The relative proportion of initiation at each site varied with the magnesium concentration for both viruses, but the LSc strain favored initiation at one site more so than did the Mahoney strain.