- Volume 73, Issue 1, 1992
Volume 73, Issue 1, 1992
- Animal
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Integration of bovine papillomavirus type 1 DNA and analysis of the amplified virus-cell junctions in transformed primary mouse fibroblasts
More LessWe have analysed the site of bovine papillomavirus type 1 (BPV-1) DNA integration in clones originating from a transformed primary mouse fibroblast cell line established by transfection of linear BPV-1 DNA. Viral DNA was integrated at a single site in the host genome with an intact early region and an almost complete long control region. Sequence analysis showed that the BPV-1 DNA was integrated at the HindIII site (the enzyme used to linearize the BPV-1 DNA for transfection) with short deletions at both ends. These deletions correspond to a 534 bp segment spanning the 3′ end of the L1 open reading frame and the replication enhancer element in the BPV-1 genome. The cellular sequences 5′ to the viral integration site exhibited 85 to 97% identity to several sequences belonging to the mouse L1 family of long interspersed repetitive sequences. Cellular sequences 3′ to the viral DNA exhibited no significant similarity to any known sequence. The BPV-1 sequences and the cellular flanking sequences were found to be amplified 45- to 50-fold. All the cell clones shared an identical integration site but one of the clones had an additional population of amplified and integrated BPV-1 DNA molecules with an internal deletion of 1136 bp in the late region. The significance of viral DNA integration at a murine long interspersed repetitive sequence containing an amplification-promoting sequence is discussed.
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Envelope protein sequences of dengue virus isolates TH-36 and TH-Sman, and identification of a type-specific genetic marker for dengue and tick-borne flaviviruses
More LessComplementary DNAs were synthesized from the envelope protein genes of two isolates of dengue virus (TH-36 and TH-Sman, previously suggested as possible dengue virus type 5 and dengue virus type 6 respectively) and amplified by the polymerase chain reaction using sense and antisense primers designed from conserved dengue virus gene sequences. The amplified cDNA clones were sequenced in both directions by double-stranded dideoxynucleotide sequencing. Alignment with published dengue virus sequences enabled us to assign these viruses accurately to classified serotypes, confirming that TH-36 and TH-Sman are strains of dengue virus type 2 and dengue virus type 1 respectively. Amino acid changes between the proteins encoded by these two isolates and strains of their respective serotypes may account for the significant antigenic differences observed during previous serological typing of these viruses. Moreover, sequence alignment of flavivirus envelope proteins revealed a hypervariable region, within which members of the dengue and tick-borne virus antigenic complexes show unique peptide sequences. This type-specific hypervariable domain may be useful as a genetic marker for typing dengue and tick-borne flaviviruses.
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Generation of a subtype-specific neutralization epitope in foot-and-mouth disease virus of a different subtype
More LessAn epitope involved in neutralization of foot-and-mouth disease virus (FMDV) of subtype C3 was generated by a single amino acid replacement in VP1 of FMDV of subtype C1. The replacement [Ser (139) → Ile, in the immunodominant site A] was consistently found in those FMDV C1 Santa Pau-Sp/70 mutants resistant to neutralization by monoclonal antibody (MAb) SD6 (specific for most C1 viruses) that acquired the capacity to be neutralized by MAb 7AB5 (specific for C3 viruses).
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- Plant
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Cleavage profiles of tobacco etch virus (TEV)-derived substrates mediated by precursor and processed forms of the TEV NIa proteinase
More LessNucleotide sequences coding for proteins containing the tobacco etch virus (TEV) NIa proteinase were generated by polymerase chain reaction amplification and/or site-directed mutagenesis. These coding regions contained sequences for the proteinase alone or as part of higher M r precursors. Following transcription and translation of these sequences in a cell-free system, the various polyproteins, all containing an active small nuclear inclusion protein (NIa) proteinase, were used to process a TEV substrate series. Most substrates were processed in a similar fashion by all proteolytic forms. However, one substrate which contained the TEV 50K/71K protein junction was differently processed by several of the polyproteins containing NIa proteinase. Substrates which previously had no identified TEV NIa proteinase cleavage sites also were tested and were not cleaved by any of the proteinase-containing polyprotein forms.
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Expression of cowpea mosaic virus coat protein precursor in transgenic tobacco plants
More LessTobacco, Nicotiana tabacum L., supports cowpea mosaic virus (CPMV) replication and cell-to-cell movement, and thus may serve as a model system to study coat protein-mediated protection against CPMV. A chimeric gene consisting of the cauliflower mosaic virus 35S promoter, CPMV 60K coat proteins-precursor (CP-P) coding region, and the nopaline synthase polyadenylation signal was transferred to tobacco cv. Burley 21 via the Agrobacterium tumefaciens binary vector system. Gene integration and expression in the transgenic tobacco plants were confirmed by Southern and RNA dot blot analyses. Accumulation of CPMV 60K CP-P in transgenic plants, up to 2 µg/g of wet weight tissue, was detected by ELISA and Western blots. The results of Western blots and immunosorbent electron microscopy further indicated that CPMV CP-P neither undergoes auto-proteolysis to generate the mature viral coat proteins nor assembles into virus-like capsids, suggesting that processing of the CP-P may be required for virus assembly. Because CPMV neither induces symptoms in tobacco nor moves systemically, evaluation of the reactions of the transgenic plants to virus inoculation was based on virus accumulation in the inoculated leaves. Results from such infectivity experiments did not differentiate between CP-P expressers and vector-transformed plants. The transgenic tobacco plants expressing CP-P should provide valuable material for investigating comovirus polyprotein processing and capsid assembly in vivo.
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Nucleotide sequence analysis of the movement genes of resistance breaking strains of tomato mosaic virus
More LessThe nucleotide sequences were determined for the movement genes, encoding 30K proteins, of two resistance breaking strains of tomato mosaic virus (ToMV), LII-ToMV and LIIA-ToMV. The putative amino acid sequences of the encoded proteins were compared with L-ToMV and with two previously published resistance breaking strains, Ltb1-ToMV and C32-ToMV. LII-ToMV, a Type 2 strain able to infect tomatoes containing the Tm-2 gene, has four amino acid changes relative to L-ToMV. One of these substitutions, Glu-Lys133, is also found in the other Type 2 strains, Ltb1-ToMV and C32-ToMV. LIIA-ToMV, a Type 22 strain able to overcome the resistance conferred by the tomato Tm-22 gene, has four amino acid differences from L-ToMV. The Type 22 strain has no substitutions in common with any of the Type 2 strains; however the predominance of amino acid substitutions that involve a change in the local charge (six out of the eight) suggests an electrostatic interaction between a host factor and the 30K protein may be intrinsic to the function of the movement gene and/or resistance breakage.
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Expression of brome mosaic virus-encoded replicase genes in transgenic tobacco plants
More LessWe introduced replicase genes of brome mosaic virus (BMV) to Nicotiana tabacum cv. Petit Habana (SR1) using two different types of transformation vectors containing cDNAs of BMV RNA 1 and RNA 2. One type (V type) contains cDNA from which complete viral RNAs are transcribed. These RNAs can function as templates for viral replicase. The other type (M type) contains cDNA from which viral RNAs without their 3′ non-coding regions are transcribed; these RNAs can only function as mRNA. Viral replicase expressed from the integrated cDNAs in both V and M type transgenic plants can complement an infection by BMV RNA 3.
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Volumes and issues
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Volume 105 (2024)
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Volume 73 (1992 - 2024)
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Volume 104 (2023)
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Volume 103 (2022)
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Volume 101 (2020)
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Volume 36 (1977)
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Volume 7 (1970)
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Volume 6 (1970)
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Volume 5 (1969)
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Volume 4 (1969)
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Volume 3 (1968)
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Volume 2 (1968)
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Volume 1 (1967)