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 775 records · Page 43Linked to original sources

PubMed2006

Production and characterization of vaccines based on flaviviruses defective in replication.

To develop new vaccine candidates for flavivirus infections, we have engineered two flaviviruses, yellow fever virus (YFV) and West Nile virus (WNV), that are deficient in replication. These defective pseudoinfectious viruses (PIVs) lack a functional copy of the capsid (C) gene in their genomes and are incapable of causing spreading infection upon infection of cells both in vivo and in vitro. However, they produce extracellular E protein in form of secreted subviral particles (SVPs) that are known to be an effective immunogen. PIVs can be efficiently propagated in trans-complementing cell lines making high levels of C or all three viral structural proteins. PIVs derived from YFV and WNV, demonstrated very high safety and immunization produced high levels of neutralizing antibodies and protective immune response. Such defective flaviviruses can be produced in large scale under low biocontainment conditions and should be useful for diagnostic or vaccine applications.

Animals↗

PubMed1977

In vitro translation of Harvey murine sarcoma virus RNA.

The viral RNA of the Harvey strain of murine sarcoma virus (Ha-SV), which does not encode for any known viral structural polypeptides, has been translated in a nuclease-digested, cell-free system. The major protein product of the in vitro translation reaction has a molecular weight of 21,000 and is initiated faithfully with [35S]formylmethionine from formyl-[35S]methionyl-tRNAFMET. This polypeptide is clearly distinct from the RNA of the Moloney strain of type C helper virus used to pseudotype the Ha-SV. The intensity of the 21,000-dalton polypeptide on gels correlates well to the concentration of Ha-SV RNA in different viral RNA preparations. These experiments indicate that a polypeptide marker for Ha-SV is now available for the first time. The possibility that this protein is the product of the rat portion of the Ha-SV genome is discussed.

Cell Line↗

PubMed1989

Rabies: ocular pathology.

Ocular pathology in the first European case of human bat-borne rabies is described. The patient was a 30-year-old bat scientist who seven weeks after bat bite developed neurological symptoms and died 23 days later. Rabies virus antigens were detected in brain smears. After extensive virological studies the virus turned out to be a rabies-related virus, closely resembling the Duvenhage virus isolated from bats in South Africa in 1980. By light microscopy focal chronic inflammatory infiltration of the ciliary body and of the choroid was found. PAS-positive exudate was seen in the subretinal and in the outer plexiform layers of the retina, and retinal veins showed endothelial damage and perivascular inflammation. Many of the retinal ganglion cells were destroyed. The presence of rabies-related viral antigen in the retinal ganglion cells was shown by positive cytoplasmic immunofluorescence, though electron microscopy failed to identify definite viral structures in the retina. By immunohistochemistry glial fibrillary acidic protein was observed in the Müller's cells, which are normally negative for this antigen but express it as a reactive change when the retina is damaged. Synaptophysin, a constituent of presynaptic vesicles of normal retinal neurons, was not detected in the retina.

Adult↗

PubMed2006

[Construction of recombinant lentivirus vaccine with single round replication].

OBJECTIVE: To develop a safe and effective lentivirus vaccine model and provide insights into the development of other lentivirus vaccines. METHODS: In this study, a construct of pGPT was made by deleting env gene in the infectious Equine infectious anemia virus (EIAV) molecular clone of WU57. Since the overlaping of EIAV Rev gene with env gene, there was no Rev gene in the construct of pGPT. For compensation of Rev function, the construct of pGPTC was made by inserting 4 copies of constitutive RNA transport elements (CTEs) from Mason-Pfizer monkey virus into the construct of pGPT. In addition, a construct designated pTEB expressing EIAV Env protein was made while env gene-minus viruses were made by co-transfection of pGPT/pTEB or pGPTC/pTEB into 293 cells. Western blot was used to identify the development of recombinant virus particles. Then immunofluorescence assay was used to evaluate the infectivity of recombinant virus particles in vitro. RESULTS: EIAV proteins expression was detected in the supernatant of transfected 293 cells by Western blot within pGPTC/pTEB transfected cells. However, no evidence of EIAV proteins expression was observed within pGPT/pTEB transfected cells. EIAV proteins expression was detected in the first round but not in the second round infected EK cells with EIAV(GPTC) by immunofluorescence assay. CONCLUSION: Rev/RRE was necessary for expression of viral structural proteins; CTEs from Mason-Pfizer monkey virus was functionally interchangeable with EIAV Rev/RRE to help RNAs transportation out of nucleus to express structural proteins and EIAV particles were produced in the transfected 293 cells. A live EIAV recombinant virus with single round infection had been developed.

Animals↗

PubMed2006

Ribosomal protein S6 associates with alphavirus nonstructural protein 2 and mediates expression from alphavirus messages.

Although alphaviruses dramatically alter cellular function within hours of infection, interactions between alphaviruses and specific host cellular proteins are poorly understood. Although the alphavirus nonstructural protein 2 (nsP2) is an essential component of the viral replication complex, it also has critical auxiliary functions that determine the outcome of infection in the host. To gain a better understanding of nsP2 function, we sought to identify cellular proteins with which Venezuelan equine encephalitis virus nsP2 interacted. We demonstrate here that nsP2 associates with ribosomal protein S6 (RpS6) and that nsP2 is present in the ribosome-containing fractions of a polysome gradient, suggesting that nsP2 associates with RpS6 in the context of the whole ribosome. This result was noteworthy, since viral replicase proteins have seldom been described in direct association with components of the ribosome. The association of RpS6 with nsP2 was detected throughout the course of infection, and neither the synthesis of the viral structural proteins nor the presence of the other nonstructural proteins was required for RpS6 interaction with nsP2. nsP1 also was associated with RpS6, but other nonstructural proteins were not. RpS6 phosphorylation was dramatically diminished within hours after infection with alphaviruses. Furthermore, a reduction in the level of RpS6 protein expression led to diminished expression from alphavirus subgenomic messages, whereas no dramatic diminution in cellular translation was observed. Taken together, these data suggest that alphaviruses alter the ribosome during infection and that this alteration may contribute to differential translation of host and viral messages.

Alphavirus↗

PubMed2005

Coronavirus reverse genetics by targeted RNA recombination.

Targeted RNA recombination was the first reverse genetics system devised for coronaviruses at a time when it was not clear whether the construction of full-length infectious cDNA clones would become possible. In its current state targeted RNA recombination offers a versatile and powerful method for the site-directed mutagenesis of the downstream third of the coronavirus genome, which encodes all the viral structural proteins. The development of this system is described, with an emphasis on recent improvements, and multiple applications of this technique to the study of coronavirus molecular biology and pathogenesis are reviewed. Additionally, the relative strengths and limitations of targeted RNA recombination and infectious cDNA systems are contrasted.

Coronavirus↗

PubMed1977

The effect of arginine deprivation on DNA, thymidine kinase and RNA polymerase synthesis in simian virus 40-infected monkey kidney cells.

In arginine-deprived cells infected with simian virus 40 (SV40), both viral DNA and viral structural proteins were synthesized but infectious virus was not produced. The syntheses of cellular DNA, thymidine kinase and DNA polymerase were induced in virus-infected cells deprived of arginine but the maximum rate of synthesis of these enzymes occurred much later than that in infected cells incubated in the presence of arginine.

Arginine↗

PubMed1972

Selective inhibition of the synthesis of Sindbis virion proteins by an inhibitor of chymotrypsin.

Treatment of chick embryo fibroblasts infected with Sindbis virus with TPCK, the choloromethyl ketone derivative of tosyl-phenylalanine and an inhibitor of chymotrypsin, resulted in reduced synthesis of viral structural proteins and the accumulation of a high-molecular-weight polypeptide, thought to be a precursor. The analogous inhibitor of trypsin, TLCK, the chloromethyl ketone derivative of tosyllysine, had no such effect.

Animals↗

PubMed1995

Characterization of revertants of a Sindbis virus 6K gene mutant that affects proteolytic processing and virus assembly.

Alphaviruses of the Togaviridae encode a small hydrophobic polypeptide of 55 amino acids, noted as the 6K protein, that is synthesized as part of a polyprotein containing the sequences of the two major transmembranal viral structural glycoproteins. Mutations, insertions and deletions in the 6K appear to selectively interfere with the final stages of virus assembly and budding, producing aberrant, multi-cored infectious viruses. In addition, some of these mutations were pleiotropic and much more inhibitory to virus formation. One of the latter, a substitution of alanine in the wild-type Sindbis virus 6K gene by arginine, has been studied further and shown to interfere with normal proteolytic processing of the polyprotein. Cells infected with this mutant but not the wild-type virus also displayed viral antigens in nuclear membranes and released fragments of membranes into the cell culture media. A revertant, obtained by enrichment for a faster growing strain, 'suppressed' these defects and genetic mapping showed that the arginine codon had been modified to encode a methionine. However, the sequence of the 6K protein in this revertant was not wild-type and the revertant was still defective in assembly as demonstrated by formation of aberrant particles. A complete restoration of wild-type particle formation for this revertant could be effected by modifying the E2 glycoprotein sequence.

Animals↗

PubMed1979

A DRB (5,6 dichloro-beta-D-ribofuranosylbenzimidazole)-resistant adenovirus mRNA.

5,6-Dichloro-beta-D ribofuranosyl benzimidazole (DRB) inhibits transcription from the major late adenovirus promoter, located on the r-strand at map position 16.3 on the viral genome. 100-500 nucleotides long RNA chains with capped 5'-termini are transcribed from this promoter in the presence of 70 muM DRB. Synthesis of the mRNA for polypeptide IX which is unspliced and maps on the r-strand between positions 9.7 and 10.9 appears, however, to be DRB-resistant although it is transcribed by polymerase II and capped. Translatable mRNA for polypeptide IX is synthesized in the presence of DRB while the mRNAs for the other viral structural proteins are not synthesized. This differential DRB-inhibition of polymerase II transcription suggests either that short mRNAs may escape inhibition or that unspliced mRNAs are insensitive to the drug.

Adenoviruses, Human↗

PubMed1977

Analysis of precursors to the envelope glycoproteins of avian RNA tumor viruses in chicken and quail cells.

Immune precipitation with monospecific antiserum was employed to study the intracellular synthesis of viral glycoproteins gp85 and gp37. Labeled gp85 and gp37 were detected from lysates of cells transformed with Rous sacroma virus, strain B77, after long-term labeling with radioactive glucosamine or phenylalanine. Immune precipitates prepared from lysates of cells pulse-labeled for a short time resulted in a glycoprotein of 92,000 molecular weight (gp92). This precursor was stable in B77-transformed Japanese quail cells for several hours, whereas in chicken cells it could be chased within a few hours into virion glycoproteins gp85 and gp37. Similarly, the precursor for the structural viral proteins, pr76, persisted in quail cells much longer than in chicken cells. During very short pulses or in the presence of a glucosamine block (25 mM glucosamine), the antiserum against the viral envelope glycoproteins detected a precursor of higher electrophoretic mobility of approximately 70,000 molecular weight, "p70." Fucose label entered gp92 and gp85 as well as "p70." Proteolytic treatment of virion-bound gp85 in vitro generated two discrete glycoproteins of 62,000 and 45,000 molecular weight, but did not result in an increase in the amount of gp37.

Animals↗

PubMed1992

The herpes simplex virus 1 RNA binding protein US11 is a virion component and associates with ribosomal 60S subunits.

The herpes simplex virus 1 US11 gene encodes a site- and conformation-specific RNA binding regulatory protein. We fused the coding sequence of this protein with that of beta-galactosidase, expressed the chimeric gene in Escherichia coli, and purified a fusion protein which binds RNA in the same way as the infected cell protein. The fusion protein was used to generate anti-US11 monoclonal antibody. Studies with this antibody showed that US11 protein is a viral structural protein estimated to be present in 600 to 1,000 copies per virion. The great majority of cytoplasmic US11 protein was found in association with the 60S subunit of infected cell ribosomes. US11 protein associates with ribosomes both late in infection at the time of its synthesis and at the time of infection after its introduction into the cytoplasm by the virion. US11 protein expressed in an uninfected cell line stably transfected with the US11 gene associates with ribosomal 60S subunits and localizes to nucleoli, suggesting that US11 protein requires no other viral functions for these associations.

Antibodies, Monoclonal↗

PubMed2005

Interactions between rubella virus capsid and host protein p32 are important for virus replication.

The distribution and morphology of mitochondria are dramatically affected during infection with rubella virus (RV). Expression of the capsid, in the absence of other viral proteins, was found to induce both perinuclear clustering of mitochondria and the formation of electron-dense intermitochondrial plaques, both hallmarks of RV-infected cells. We previously identified p32, a host cell mitochondrial matrix protein, as a capsid-binding protein. Here, we show that two clusters of arginine residues within capsid are required for stable binding to p32. Mutagenic ablation of the p32-binding site in capsid resulted in decreased mitochondrial clustering, indicating that interactions with this cellular protein are required for capsid-dependent reorganization of mitochondria. Recombinant viruses encoding arginine-to-alanine mutations in the p32-binding region of capsid exhibited altered plaque morphology and replicated to lower titers. Further analysis indicated that disruption of stable interactions between capsid and p32 was associated with decreased production of subgenomic RNA and, consequently, infected cells produced significantly lower amounts of viral structural proteins under these conditions. Together, these results suggest that capsid-p32 interactions are important for nonstructural functions of capsid that include regulation of virus RNA replication and reorganization of mitochondria during infection.

Amino Acid Sequence↗

PubMed1997

[Diagnostic criteria for Non-ABCDE hepatitis].

Hepatitis viruses A, B, C, D and E are all well-characterized, molecularly defined agents with unequivocal disease association. Usual diagnosis for these virus infections are established by serological markers which are specific antigens or antibodies for these virus infections. But serological diagnosis occasionally shows pseudonegative results because this method is indirect diagnosis. In contrast, molecular diagnosis catches directly components of viral structure. Molecular diagnosis is also able to show the appearance and disappearance of these hepatitis viruses. Diagnostic criteria for Non-ABCDE hepatitis is the exclusion of hepatitis viruses A, B, C, D and E infections by using not only serological diagnosis but also molecular diagnosis.

Acute Disease↗

PubMed2001

Rescue of recombinant Thogoto virus from cloned cDNA.

Thogoto virus (THOV) is a tick-transmitted orthomyxovirus with a genome consisting of six negative-stranded RNA segments. To rescue a recombinant THOV, the viral structural proteins were produced from expression plasmids by means of a vaccinia virus expressing the T7 RNA polymerase. Genomic virus RNAs (vRNAs) were generated from plasmids under the control of the RNA polymerase I promoter. Using this system, we could efficiently recover recombinant THOV following transfection of 12 plasmids into 293T cells. To verify the recombinant nature of the rescued virus, specific genetic tags were introduced into two vRNA segments. The availability of this efficient reverse genetics system will allow us to address hitherto-unanswered questions regarding the biology of THOV by manipulating viral genes in the context of infectious virus.

Animals↗

PubMed1991

Cytokine enhancement of simian immunodeficiency virus (SIV/mac) from a chronically infected cloned T-cell line (HuT-78).

Simian immunodeficiency viruses (SIV) are a family of primate lentiviruses similar to human immunodeficiency viruses (HIV) in their genetic sequence and pathogenesis. However, host-derived cofactors which may determine the extent of viral replication are not clearly defined for SIV or HIV infections. A HuT-78 cell line chronically infected with SIV/mac strain 251, was biologically cloned and characterized for the ability to produce infectious viral particles, viral structural protein profile, cellular antigen surface phenotype and tested to determine the effects of recombinant cytokines on SIV replication. Reverse transcriptase (RT) assay was used to measure the replication of SIV/mac in response to various concentrations of recombinant cytokines (1-1000 units/ml). We report that tumor necrosis factor-alpha (rTNF-alpha), gamma-interferon (rIFN-gamma), interleukin 2 (rIL-2), and granulocyte-macrophage colony stimulating factor (rGM-CSF) induced approximately a 2 to 3 fold increase in virus RT activity compared with untreated SIV-infected HuT-78 cells. In contrast, viral replication was not enhanced or minimally enhanced by interleukin 1 (rIL-1), interleukin 3 (rIL-3), or interleukin 4 (rIL-4) at similar dosages. Furthermore, SIV replication in response to rTNF-alpha and rIFN-gamma occurred in a dose dependent fashion. These data suggest that SIV-infected T-lymphocyte lines are responsive to particular cytokines resulting in increased virus production.

Cell Line↗

PubMed1996

Interference to human immunodeficiency virus type 1 infection in the absence of downmodulation of the principal virus receptor, CD4.

It is thought that interference during human immunodeficiency virus type 1 (HIV-1) infection is established by downmodulation of the principal virus receptor, CD4. Here we present evidence to the contrary. At various times after primary infection, we superinfected T cells in vitro by exposure to a genetically distinct viral clone or to a virus carrying the chloramphenicol acetyltransferase gene. Replication of each virus strain was determined by restriction enzyme analysis of total cellular DNA, by PCR amplification of viral DNA, or by assay of cell extracts for chloramphenicol acetyltransferase activity. We found that efficient viral interference is established within 24 h of infection at a multiplicity of infection of 1. At that time, expression of viral structural proteins was low and infected cells displayed undiminished levels of surface CD4 and were fully susceptible to virus binding and fusion. Superinfection by either cell-free HIV-1 or cocultivation was blocked. Cells resistant to superinfection by HIV-1 remained susceptible to Moloney murine leukemia and vaccinia viruses. No interference was observed 4 h after primary infection or in cells infected with either UV-inactivated HIV-1 or a mutant virus defective in virus-cell fusion activity, indicating that binding of primary virus to CD4 is insufficient to prevent superinfection. The minimum viral requirements for this interference are that HIV-1 must be able to enter cells and synthesize viral DNA; Tat-mediated transcription is dispensable. Our results support the existence of a novel pathway to interference to HIV-1 infection, which we term postentry interference, which blocks superinfection during intracellular phases of the virus life cycle.

Base Sequence↗

PubMed2002

A variable region on the chlorovirus CVK2 genome contains five copies of the gene for Vp260, a viral-surface glycoprotein.

A 22.2-kb variable region near the left end of the chlorovirus CVK2 genome that was previously supposed to be expanded compared to the PBCV-1 genome was characterized. This region contains a tandem array of five gene copies for the Vp260-like protein, a viral-surface glycoprotein. The authentic 104-kDa Vp260 was found to be encoded at another site on the genome and to contain 13 internal tandem repeats of 61-65 amino acids, similar to the prominent Rickettsia surface antigen. The extra copies were also found to retain 10 of the internal repeats, despite the C-terminal deletions or extensions. These extra copies are conserved among chloroviruses isolated in various areas of Japan. By Northern blot analysis, these genes were demonstrated to be expressed late in infection. The proteins are incorporated into virions, as revealed by comparing viral structural proteins between wild-type and deletion mutants. These results indicate that extra copies of Vp260-like proteins encoded in a variable region on the genome may give variations in the surface nature of the chloroviral particles.

Amino Acid Sequence↗