SEARCH · PubMed Health

Results for “Viral Structures”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 577 records · Page 32Linked to original sources

PubMed2002

The assembly of Ebola virus nucleocapsid requires virion-associated proteins 35 and 24 and posttranslational modification of nucleoprotein.

Ebola virus encodes seven viral structural and regulatory proteins that support its high rates of replication, but little is known about nucleocapsid assembly of this virus in infected cells. We report here that three viral proteins are necessary and sufficient for formation of Ebola virus particles and that intracellular posttranslational modification regulates this process. Expression of the nucleoprotein (NP) and virion-associated proteins VP35 and VP24 led to spontaneous assembly of nucleocapsids in transfected 293T cells by transmission electron microscopy. A specific biochemical interaction of these three proteins was demonstrated, and, interestingly, O-glycosylation and sialation of NP were demonstrated and necessary for their association. This distinct mechanism of regulation for filovirus assembly suggests new approaches for viral therapies and vaccines for Ebola and related viruses.

Amino Acid Sequence↗

PubMed2006

Use of modified U1 snRNAs to inhibit HIV-1 replication.

Control of RNA processing plays a central role in regulating the replication of HIV-1, in particular the 3' polyadenylation of viral RNA. Based on the demonstration that polyadenylation of mRNAs can be disrupted by the targeted binding of modified U1 snRNA, we examined whether binding of U1 snRNAs to conserved 10 nt regions within the terminal exon of HIV-1 was able to inhibit viral structural protein expression. In this report, we demonstrate that U1 snRNAs complementary to 5 of the 15 regions targeted result in significant suppression of HIV-1 protein expression and viral replication coincident with loss of viral RNA. Suppression of viral gene expression is dependent upon appropriate assembly of a U1 snRNP particle as mutations of U1 snRNA that affect binding of U1 70K or Sm proteins significantly reduced efficacy. However, constructs lacking U1A binding sites retained significant anti-viral activity. This finding suggests a role for these mutants in situations where the wild-type constructs cause toxic effects. The conserved nature of the sequences targeted and the high efficacy of the constructs suggests that this strategy has significant potential as an HIV therapeutic.

Anti-HIV Agents↗

PubMed1973

Reovirus: effect of noninfective viral components on cellular deoxyribonucleic acid synthesis.

We determined the effects of noninfective reovirus components on cellular deoxyribonucleic acid (DNA) synthesis. Reovirus inactivated by ultraviolet light inhibited cellular DNA synthesis, whereas reovirus cores and empty capsids did not. Both cores and empty capsids were adsorbed to cells. Adenine-rich ribonucleic acid (RNA) from reovirus, adsorbed to cells in the presence of diethyl-aminoethyl-dextran, produced a partial inhibition of DNA synthesis. RNA was synthesized in the presence of actinomycin D after infection with ultraviolet light-irradiated reovirus, and this RNA synthesis was not due to multiplicity reactivation of virus infectivity. These data suggest that viral structural proteins do not inhibit DNA synthesis and that the inhibition produced by ultraviolet-irradiated virus may be mediated in part or in toto by a newly synthesized viral product.

Animals↗

PubMed1984

Characterization of temperature-sensitive mutants of simian rotavirus SA11: protein synthesis and morphogenesis.

The synthesis of viral polypeptides, distribution of viral antigens, and morphogenesis of viral structures have been examined in cells infected with temperature-sensitive (ts) mutants of SA11 representing 10 recombination groups. At the permissive temperature (31 degrees C) the synthesis of viral polypeptides and the distribution of viral antigens did not differ significantly from those of the wild type. At the nonpermissive temperature (39 degrees C) some mutants (tsB, -C, -E, -F, and -G) synthesized significantly smaller amounts of viral polypeptides and had a very diffuse distribution of viral antigen. Several of the mutants synthesized one or more electrophoretically aberrant polypeptide species at both 31 and 39 degrees C. All of the mutants, except tsF, assembled morphogenetic intermediates at 39 degrees C. Aberrant intermediates were assembled in all mutants at 31 and 39 degrees C. No specific morphogenic defect could be associated with any of the ts mutants.

Animals↗

PubMed2005

Sulfolobus tengchongensis spindle-shaped virus STSV1: virus-host interactions and genomic features.

A virus infecting the hyperthermophilic archaeon Sulfolobus tengchongensis has been isolated from a field sample from Tengchong, China, and characterized. The virus, denoted STSV1 (Sulfolobus tengchongensis spindle-shaped virus 1), has the morphology of a spindle (230 by 107 nm) with a tail of variable length (68 nm on average) at one end and is the largest of the known spindle-shaped viruses. After infecting its host, the virus multiplied rapidly to high titers (>10(10) PFU/ml). Replication of the virus retarded host growth but did not cause lysis of the host cells. STSV1 did not integrate into the host chromosome and existed in a carrier state. The STSV1 DNA was modified in an unusual fashion, presumably by virally encoded modification systems. STSV1 harbors a double-stranded DNA genome of 75,294 bp, which shares no significant sequence similarity to those of fuselloviruses. The viral genome contains a total of 74 open reading frames (ORFs), among which 14 have a putative function. Five ORFs encode viral structural proteins, including a putative coat protein of high abundance. The products of the other nine ORFs are probably involved in polysaccharide biosynthesis, nucleotide metabolism, and DNA modification. The viral genome divides into two nearly equal halves of opposite gene orientation. This observation as well as a GC-skew analysis point to the presence of a putative viral origin of replication in the 1.4-kb intergenic region between ORF1 and ORF74. Both morphological and genomic features identify STSV1 as a novel virus infecting the genus Sulfolobus.

Archaeal Viruses↗

PubMed1984

Differences between translation products of tick-borne encephalitis virus RNA in cell-free systems from Krebs-2 cells and rabbit reticulocytes: involvement of membranes in the processing of nascent precursors of flavivirus structural proteins.

Tick-borne encephalitis virus (TBEV) RNA was translated in extracts from Krebs-2 cells and in rabbit reticulocyte lysates. In the former system, two polypeptides, p53 and p13, corresponding to envelope (E) and core (C) proteins of the virion, respectively, were synthesized preferentially. In contrast, the major product in reticulocyte lysates was represented by a heterogeneous set of high-molecular-weight polypeptides which did not appear to include p53 or p13. The reticulocyte lysates, however, acquired the ability to produce structural proteins (p53 at least) after addition of purified membranes isolated from the rough endoplasmic reticulum of Krebs-2 cells. On the other hand, the ability of Krebs-2 extracts to generate identifiable viral structural proteins was lost after degradation of membranes by the nonionic detergent Triton X-100. These findings strongly suggest that membrane-dependent processing of protein precursors is involved in the formation of TBEV structural proteins. Evidence has been obtained that only nascent precursor polypeptides can be processed efficiently into structural proteins in the membrane-dependent reaction.

Animals↗

PubMed1954

Structure and development of viruses as observed in the electron microscope. I. Herpes simplex virus.

Herpes simplex virus was visualized by the electron microscope in sections of infected chorioallantoic membrane of chicken embryos. Removal of the embedding methacrylate from relatively thick sections permitted large numbers of viral particles to be seen but caused extensive alteration of cellular components as well as variable distortion of viral structure. This distortion was characterized by disruption of particles and loss of central bodies, resulting in ring or empty shell forms. An inner structure of the virus was revealed in ultrathin sections from which the embedding plastic was not removed. The nuclei of infected cells contained small, dense, primary bodies (30 to 40 mmicro in diameter) as well as slightly larger and less dense particles (40 to 50 mmicro in diameter) surrounded by a single membrane (70 to 100 mmicro in diameter). In the cytoplasm most of the particles possessed a double outer membrane (120 to 130 mmicro in diameter). It is suggested that the initial site of viral development is restricted to the nucleus where primary bodies form and become enclosed by a single outer membrane. Upon release into the cytoplasm these particles appear to acquire a second outer membrane and presumably represent the mature virus.

Animals↗

PubMed1973

Group B arbovirus structural and nonstructural antigens. I. Serological identification of Saint Louis encephalitis virus soluble antigens.

Saint Louis encephalitis virus-infected cells were solubilized with Brij-58 nonionic detergent, and the clarified supernatant fluid was analyzed by diethyl-aminoethyl-cellulose chromatography. Three serologically distinguishable antigens were identified in viral protein peaks which eluted from diethylaminoethyl-cellulose at 0.05, 0.075, 0.125 and 0.2 m KCl. Antigen I was found in all column peaks, whereas antigen II was found only in the 0.05 m KCl eluate and antigen III was found only in the 0.2 m eluate. Immunodiffusion studies revealed that antigens I and II share at least one antigenic determinant and that antigen III is immunologically distinct from either antigen I or II. Polyacrylamide gel electrophoresis of (3)H-leucine-labeled concentrated column peaks revealed that antigens I and II contain the major viral structural envelope and core proteins, respectively. Antigen III contains the largest virus-induced nonstructural polypeptide observed by polyacrylamide gel electrophoresis of (3)H-leucine-labeled Saint Louis encephalitis virus-infected cells.

Animals↗

PubMed2002

Structural variation and functional importance of a D-loop-T-loop interaction in valine-accepting tRNA-like structures of plant viral RNAs.

Valine-accepting tRNA-like structures (TLSs) are found at the 3' ends of the genomic RNAs of most plant viruses belonging to the genera Tymovirus, Furovirus, Pomovirus and Pecluvirus, and of one Tobamovirus species. Sequence alignment of these TLSs suggests the existence of a tertiary D-loop-T-loop interaction consisting of 2 bp, analogous to those in the elbow region of canonical tRNAs. The conserved G(18).Psi(55) pair of regular tRNAs is found to covary in these TLSs between G.U (possibly also modified to G.Psi) and A.G. We have mutated the relevant bases in turnip yellow mosaic virus (TYMV) and examined the mutants for symptom development on Chinese cabbage plants and for accumulation of genetic reversions. Development of symptoms is shown to rely on the presence of either A.G or G.U in the original mutants or in revertants. This finding supports the existence and functional importance of this tertiary interaction. The fact that only G.U and A.G are accepted at this position appears to result from steric and energetic limitations related to the highly compact nature of the elbow region. We discuss the implications of these findings for the various possible functions of the valine-accepting TLS.

Base Sequence↗

PubMed1984

Inhibition of the synthesis of Moloney leukemia virus structural proteins by N-methylisatin-beta-4',4'-diethylthiosemicarbazone.

The mechanism of inhibition of Moloney leukemia virus by N-methylisatin-beta-4',4'-diethylthiosemicarbazone was studied. Experiments that used [3H]leucine for short-pulse labeling in the presence of the drug resulted in a 71% inhibition in the synthesis of Pr-80, the polypeptide precursor of the gag viral proteins. The radioactive pulse products of the polypeptide precursors after a further 2-h chase period showed a normal cleavage of the precursors, with the formation of a reduced amount of final mature viral structural proteins. The experimental evidence indicated that at the inhibitory concentration of 17 microM N-methylisatin-beta-4',4'-diethylthiosemicarbazone, the amount of intracellular viral RNA was not affected, whereas the activities of reverse transcriptase and the other viral protein syntheses were suppressed.

Animals↗

PubMed1987

The development and characterization of monoclonal antibodies against rat cytomegalovirus induced antigens.

In this paper the development of a battery of approximately 70 mouse monoclonal antibodies (McAbs) to RCMV-induced antigens and their characterization is discussed. Their reactivity with the whole scala of ca. 30 virus specific proteins was tested in an enzyme linked immunoassay (ELISA) whereas their ability to detect RCMV-antigens at different locations of in vitro infected cell cultures and at different stages of infection was tested by immunofluorescence. In order to determine to what specific (viral) protein each of these McAbs is directed against we used an immunoprecipitation technique, followed by SDS-PAGE. Furthermore, neutralizing capacity of each McAb was tested, as well as the immunoglobulin class they belong to. In this manner we defined six categories of monoclonal antibodies on the basis of immunofluorescence aspect. The six categories identify most important viral structural proteins.

Animals↗

PubMed2004

Identification of structural proteins from shrimp white spot syndrome virus (WSSV) by 2DE-MS.

White spot syndrome virus (WSSV) is a major shrimp pathogen that also infects many other species of crustaceans. Its 305-kb double-stranded DNA genome has the capacity to encode 181 presumptive proteins. In an attempt to identify the viral proteins from the 181 theoretical proteins, proteins of the purified WSSV were separated by two-dimensional electrophoresis (2-DE). More than 60 protein spots were revealed, as detected by silver staining, from which 12 viral proteins were identified by mass spectrometry. In total, 25 WSSV proteins, including those reported in one of our earlier studies (Huang et al., Mol Cell Proteomics 2002;1:223-231), were revealed by this proteomic approach, and their corresponding genes were further confirmed by reverse transcription-polymerase chain reaction (RT-PCR). Two of them were characterized to be WSSV envelope proteins using immuno-electron microscopy. Our study showed that the proteomic approach is a powerful method for discovering the viral structural proteins and their corresponding genes.

Animals↗

PubMed1987

CD8-positive T lymphocytes specific for murine cytomegalovirus immediate-early antigens mediate protective immunity.

We have shown in a murine model system for acute, lethal cytomegalovirus (CMV) disease in the immunocompromised natural host that control of virus multiplication in tissues, protection from virus-caused tissue destruction, and survival are mediated by virus-specific CD8+ CD4-T lymphocytes. Protection from a lethal course of disease did not result in a rapid establishment of virus latency, but led to a long-lasting, persistent state of infection. The CD8- CD4+ subset of T lymphocytes was not effective by itself in controlling murine CMV (MCMV) multiplication in tissue or essential for the protective function of the CD8+ CD4- effector cells. The antiviral efficacy of the purified CD8+ CD4- subset was not impaired by preincubation with fibroblasts that presented viral structural antigens, but was significantly reduced after depletion of effector cells specific for the nonstructural immediate-early antigens of MCMV, which are specified by the first among a multitude of viral genes expressed during MCMV replication in permissive cells. Thus, MCMV disease provides the first example of a role for nonstructural herpesvirus immediate-early antigens in protective immunity.

Animals↗

PubMed1989

Antibody reactivity to cytomegalovirus structural polypeptides in subclinical and clinical human immunodeficiency virus infections.

A total of 56 sera from asymptomatic HIV-seropositive subjects and patients with symptomatic HIV infection were studied by immunoblotting for IgM, IgG and IgG subclass reactivity against cytomegalovirus structural polypeptides. The results showed a high percentage of IgM-positive sera in the asymptomatic patients, and IgM reactivity was particularly high against a polypeptide of intermediate molecular weight (p66). IgG reactivity was very high against the majority of viral structural polypeptides with the possible exceptions of p82 and p61, in all patients. Antibody to these polypeptides decreased with the increase in HIV-specific symptoms. No significant difference in the reactivity of IgG subclass to viral polypeptides was found among the different groups of subjects, except for a generalized increase in IgG subclass reactivity from asymptomatic to HIV-specific symptomatic patients.

AIDS-Related Complex↗

PubMed1981

Structural complexity of defective-interfering RNAs of Semliki Forest virus as revealed by analysis of complementary DNA.

The 18S defective interfering RNA of Semliki Forest virus has been reverse transcribed to cDNA, which was shown to be heterogeneous by restriction enzyme analysis. After transformation to E.coli, using pBR322 as a vector, two clones, pKTH301 and pKTH309 with inserts of 1.7 kb and 2 kb, were characterized, respectively. The restriction maps of the two clones were different but suggested that both contained repeating units. At the 3' terminus, pKTH301 had preserved 106 nucleotides and pKTH309 102 nucleotides from the 3' end of the viral 42S genome. The conserved 3' terminal sequence was joined to a different sequence in the two clones, and these sequences were not derived from the region coding for the viral structural proteins. The DI RNAs represented by the two clones are generated from the viral 42S RNA by several noncontinuous internal deletions, since the largest colinear regions with 42S RNA are 320 nucleotides in pKTH301, and 430 and 340 nucleotides in pKTH309. All these fragments had unique RNase T1 oligonucleotide fingerprints, suggesting that they were derived from different regions of 42S RNA.

Base Composition↗

PubMed1990

Structure and expression of tat-, rev-, and nef-specific transcripts of human immunodeficiency virus type 1 in infected lymphocytes and macrophages.

Primary RNA transcripts from the human immunodeficiency virus type 1 (HIV-1) are processed into mature mRNA by a complex series of splicing events. Viral structural proteins and reverse transcriptase are translated from unspliced or singly spliced transcripts. Proteins which control virus replication, including tat, rev, and nef, are translated from transcripts which are the product of multiple splicing. We have analyzed the composition and relative abundance of the latter transcripts in long-term infected cell lines and in acutely infected peripheral blood cells by amplification with the polymerase chain reaction (PCR) followed by Southern blot, molecular cloning, and DNA sequence analyses. In H9 cells chronically infected with the HIV-1 strain HTLV-IIIB, the predominant of the three kinds of transcripts is those coding for nef. Transcripts with coding potential for rev constituted an intermediate fraction of those analyzed, while those for tat accounted for only a small minority. A similar pattern was observed with Southern blots of PCR-amplified transcripts from peripheral blood lymphocytes acutely infected with HTLV-IIIB. The same general pattern was also observed with PCR-amplified transcripts from peripheral blood monocyte-macrophages infected with an HIV-1 strain (BA-L) able to grow to high titers in macrophages. In these cells, however, the apparent major form of nef transcript contained only the first and third exons of the multiply spliced transcripts and appeared to be generated by either a single or a triple splicing mechanism. As with lymphocytes, tat-specific mRNAs were by far the least abundant. It thus appears that different cell types infected with different strains of HIV-1 maintain a similar balance of expression in which transcripts for nef vastly predominate over those for tat and that those for rev are intermediate in abundance.

Amino Acid Sequence↗

PubMed1974

Expression of murine leukemia virus structural antigens on the surface of chemically induced murine sarcomas.

Cultured cells of different chemically-induced C57BL/6N murine sarcomas produced variable amounts of infectious murine leukemia virus (MuLV) and contained proportional amounts of MuLV structural components as determined by radioimmunoassay. Monospecific antisera directed against the major MuLV glycoprotein (gp71), the major internal antigen (p30), and the ribonucleoprotein (p10) were capable of mediating tumor cell lysis in the presence of complement, suggesting that these viral structural components were localized at least in part to the cell surface. Membrane immunofluorescence studies with MuLV p30 antiserum confirmed surface localization. Addition of MuLV p30 polypeptide to normal cells and tumor cells enhanced the cytotoxicity of MuLV p30 antiserum. Studies are presented which suggest that the presence of MuLV structural components on cell surfaces can be independent of virus production and cellular transformation.

Animals↗

PubMed1995

Genesis of Sindbis virus by in vivo recombination of nonreplicative RNA precursors.

Genetically engineered RNA transcripts coding for various Sindbis virus (SIN) genes were used to study structure and sequence requirements of RNA recombination in BHK cells. Three different groups of RNA transcripts were made: (i) RNAs which retain the ability to replicate and which carry sequences coding for either viral polymerase or viral structural proteins; (ii) RNAs which lack the complete 3' end of the SIN genome and thus are incapable of replicating; and (iii) RNAs which lack the complete 5' end of the SIN genome and also are incapable of replicating. BHK cells were transfected with specific combinations of these precursor RNAs, and virus production and RNA synthetic abilities of the released virus were determined. We demonstrate in vivo generation of infectious SIN by fusion of (i) replicative RNAs to nonreplicative RNAs and (ii) two nonreplicative RNA precursors. Both homologous and nonhomologous types of recombinations were observed. In the homologous type of recombination, a 694-nucleotide overlap at the crossover region of the first pair of precursors resulted in the addition of an A residue converting the UAG stop codon of nonstructural protein P4 to a UAA stop codon. In the nonhomologous type of recombination, the crossover sites contained deletion of up to 76 nucleotides from one of the precursors and complete preservation of junction sequence from the other precursor. This is also the first report that a cytoplasmic RNA virus can be generated from biologically nonreplicative RNA precursors. These results have implications for initiation of viral RNA synthesis and recombination between RNA viral genomes in general. We favor template switching as a mechanism for the fusion events described here and suggest inclusion of polymerase scanning of diverse nonreplicative RNAs as an inherent feature of the copy choice model of RNA recombination. Very importantly, the facile nature of RNA recombination occurring between nonreplicative RNA precursors should speed up the production and analysis of targeted mutants of SIN and possibly other RNA viruses.

Animals↗