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 361 records · Page 20Linked to original sources

PubMed1983

Host range temperature-conditional mutants in the adenovirus DNA binding protein are defective in the assembly of infectious virus.

R(ts107)202 is a host range temperature-conditional mutant of adenovirus type 5. This mutant is temperature sensitive for replication and plaquing in 293 cells but is temperature independent for growth and plaquing in HeLa cells (J. C. Nicolas, F. Suarez, A. J. Levine, and M. Girard (1981) Virology 108, 521-524). The mutant was isolated in HeLa cells as a temperature-independent revertant of the H5ts107 temperature-sensitive mutant that maps in the adenovirus DNA binding protein (DBP). The reasons for the temperature conditional phenotype of this mutant in 293 cells were investigated. The mutant synthesized an unstable DBP in both HeLa and 293 cells at 39 degrees. In 293 cells at 39 degrees, about two- to threefold less viral DNA was synthesized by r(ts107)202 as compared to Ad5wt. R(ts107)202 infected cells at 39 degrees produced normal (wild-type) amounts of all detectable late viral structural proteins. The mutant failed, however, to produce infectious virus or assemble virus particles in 293 cells at 39 degrees. The altered DBP may therefore play a role in the assembly of virus particles, either directly or indirectly via an altered DNA structure. The failure of r(ts107)202 to assemble virion particles in 293 cells at 39 degrees furthermore suggests that virus assembly is dependent upon cellular factors that differ in HeLa and 293 cell.

Adenoviruses, Human↗

PubMed2006

Rotavirus activates JNK and p38 signaling pathways in intestinal cells, leading to AP-1-driven transcriptional responses and enhanced virus replication.

Rotavirus infection is known to regulate transcriptional changes in many cellular genes. The transcription factors NF-kappaB and AP-1 are activated by rotavirus infection, but the upstream processes leading to these events are largely unidentified. We therefore studied the activation state during rotavirus infection of c-Jun NH2-terminal kinase (JNK) and p38, which are kinases known to activate AP-1. As assessed by Western blotting using phospho-specific antibodies, infection with rhesus rotavirus (RRV) or exposure to UV-psoralen-inactivated RRV (I-RRV) resulted in the activation of JNK in HT-29, Caco-2, and MA104 cells. Activation of p38 during RRV infection was observed in Caco-2 and MA104 cells but not in HT-29 cells, whereas exposure to I-RRV did not lead to p38 activation in these cell lines. Rotavirus strains SA11, CRW-8, Wa, and UK also activated JNK and p38. Consistent with the activation of JNK, a corresponding increase in the phosphorylation of the AP-1 component c-Jun was shown. The interleukin-8 (IL-8) and c-jun promoters contain AP-1 binding sequences, and these genes have been shown previously to be transcriptionally up-regulated during rotavirus infection. Using specific inhibitors of JNK (SP600125) and p38 (SB203580) and real-time PCR, we showed that maximal RRV-induced IL-8 and c-jun transcription required JNK and p38 activity. This highlights the importance of JNK and p38 in RRV-induced, AP-1-driven gene expression. Significantly, inhibition of p38 or JNK in Caco-2 cells reduced RRV growth but not viral structural antigen expression, demonstrating the potential importance of JNK and p38 activation for optimal rotavirus replication.

Animals↗

PubMed1986

Patterns of polypeptide synthesis in human rotavirus infected cells.

Polypeptide analysis of three strains of human rotavirus (KUN, Wa and MO) were conducted using a hypertonic culture which suppressed host protein synthesis and unmasked rotavirus specific protein synthesis. As a result, eleven human rotavirus specific polypeptides (Vp 1--Vp 11) were detected by pulselabeling infected cells with [14C]-leucine. Among the 11 polypeptides, three polypeptides (Vp 7, Vp 10 and Vp 11) underwent post-translational processing, and two (Vp 7 and Vp 10) were glycosylated. Six polypeptides (Vp 1, 2, 3, 4, 6 and 7) were identified as viral structural proteins. Comparisons of three strains of different serotypes revealed that their polypeptide profiles differed from each other in electrophoretic mobility; in particular, profiles of the glycosylated polypeptide, Vp 7, were distinct among the three strains.

Animals↗

PubMed1986

Similarities and dissimilarities in the structure and expression of viral genomes of various virus strains immunologically related to Marek's disease virus.

Various strains immunologically related to Marek's disease virus (MDV) have been subdivided into three serotypes: serotype 1, pathogenic strains of MDV and attenuated or apathogenic variants derived from them; serotype 2, naturally occurring apathogenic strains of MDV; serotype 3, herpesvirus of turkey (HVT). The viral genome structures of these three serotypes were compared by a simple, practical method using total DNA extracted from virus-infected cells instead of viral DNA purified from virions. The restriction endonuclease-cleavage patterns of serotype 2 viral DNA were found to differ from those of either serotype 1 MDV or serotype 3. Under stringent conditions, no significant DNA homology was detected among the three serotype viruses, except in a restricted portion of these viral genomes. Northern blot hybridization experiments suggested that virus-specific polyadenylated RNA of about 2.4 kilobases was transcribed from a restricted portion showing close homology in these viruses. Southern blot hybridization under less stringent conditions revealed that regions with weak homology were distributed over most of the viral genomes of the three serotypes. Two types of virus-specific glycoproteins, gA and gB, were identified in the immunoprecipitates of the culture medium and cell lysates, respectively, of serotype 2-infected cultures with monoclonal antibodies or hyperimmune antisera cross reactive with serotype 1 MDV and serotype 3 HVT, and detected on the surface of serotype 2-infected cells by the membrane immunofluorescence test. These results indicate a close evolutionary relationship among these three viral serotypes.

Animals↗

PubMed1994

[The effect of Sindbis virus multiplication on gene expression of host cells].

Sindbis virus (SBV) infection mediated a rapid shutoff of host cellular gene expression (mRNA synthesis and protein synthesis); however the synthesis of cellular rRNA remained at the same level as the uninfected cells. Meanwhile a cellular protein P105 was shown to be enriched in the nuclear matrix. Actionmycin D treatment after virus infection resulted in an apparent reduce in the production of viral structural proteins and infectious virions. The results presented here not only demonstrated the complexity of SBV-mediated regulation of host gene expression, but also suggested SBV nonstructural protein nsP2 and capsid protein C were possibly involved in this process.

Animals↗

PubMed1992

SJL/J resistance to mouse hepatitis virus-JHM-induced neurologic disease can be partially overcome by viral variants of S and host immunosuppression.

The basis of the resistance of SJL/J mice to various strains of mouse hepatitis virus (MHV) has been the subject of some debate, especially as it relates to the number and nature of the determinants involved. Our previous work demonstrated that resistance by primary SJL/J glial cultures may involve events subsequent to viral gene expression, possibly due to a defect in cell-to-cell spread of the infection. Since S, the virion's major spike glycoprotein, is known to facilitate the spread of infection due to its syncytiogenic properties, we decided to investigate the role of this viral structural protein in resistance by primary SJL/J glial cells. Variants possessing deletions within the S coding region were able to grow in SJL/J glial cells 10-100 times easier and fuse five-times more efficiently than wt virus. Induction of neurologic disease in SJL/J mice following intracranial inoculation with either wt JHMV or the S deletion variant, AT11f cord, was age-dependent, occurring only in animals inoculated under 4 weeks of age. Resistance in older animals to wt and variant viruses could be abrogated by immunosuppression with cyclosporin A. However, both disease incidence and viral brain titers were higher in animals receiving the JHM variant AT11f cord virus, suggesting that SJL/J resistance to neurologic disease may manifest itself through interactions between inefficient cell-to-cell spread of the infection and protective aspects of the immune response.

Animals↗

PubMedDate not supplied

Characterization of monoclonal antibodies to avian leukosis viruses.

Hybridoma cell lines secreting monoclonal antibody (MCA) to avian leukosis virus (ALV) structural proteins p27 and p19 have been established. In an indirect enzyme-linked immunosorbent assay (ELISA), MCA 6AL20 (IgG1 isotype) reacted with RPL-40 (ALV subgroup A), avian myeloblastosis virus (AMV) (a mixture of subgroups A and B), Rous-associated virus (RAV)-2 (subgroup B), and Carr-Zilber strain of Rous sarcoma virus (CZ-RSV) (subgroup D) but not with Prague strain of RSV (PrC-RSV) (subgroup C) or the endogenous virus RAV-0 (subgroup E). MCA 6AL22 reacted as above and also reacted marginally with PrC-RSV. Both MCAs immunoprecipitated p19 from 35S-methionine-labeled chicken embryo fibroblasts (CEFs) infected with RPL-40 or RAV-1, but not from CEFs infected with RAV-0, thus identifying the viral structural protein p19 as a polypeptide with subgroup-specific epitopes. Both MCAs can be used to differentiate RPL-40 from RAV-0 infection either in an indirect antibody ELISA or by immunoprecipitation. A third MCA, 6AL42 (IgG2a isotype), reacted with the above viruses of subgroups A, B, C, and D at an antibody titer up to 1000-fold higher than with subgroup E RAV-0 virus in indirect ELISAs. MCA 6AL42 immunoprecipitated p27 from cells infected with RPL-40, RAV-1, or RAV-0. These MCAs are potentially useful in developing immunological tests for differentiation of ALV strains.

Animals↗

PubMed2006

Application of the use of high-throughput technologies to the determination of protein structures of bacterial and viral pathogens.

The Structural Proteomics In Europe (SPINE) programme is aimed at the development and implementation of high-throughput technologies for the efficient structure determination of proteins of biomedical importance, such as those of bacterial and viral pathogens linked to human health. Despite the challenging nature of some of these targets, 175 novel pathogen protein structures (approximately 220 including complexes) have been determined to date. Here the impact of several technologies on the structural determination of proteins from human pathogens is illustrated with selected examples, including the parallel expression of multiple constructs, the use of standardized refolding protocols and optimized crystallization screens.

Animals↗

PubMed1997

The gene encoding the capsid protein P82 of the Choristoneura fumiferana multicapsid nucleopolyhedrovirus: sequencing, transcription and characterization by immunoblot analysis.

A gene encoding a capsid-associated viral structural protein has been identified and sequenced in the genome of the Choristoneura fumiferana multicapsid nucleopolyhedrovirus (CfMNPV). The gene has a 1872 nucleotide open reading frame (ORF) encoding 624 amino acids with a predicted molecular mass of 71.4 kDa. Transcription, which appeared to be initiated from a conserved GTAAG motif of baculovirus late genes, was detected at 12 h, reached a maximum at 48 h and declined at 72 h post-infection (p.i.). Part of the ORF was cloned in frame into a prokaryotic expression vector, pMAL-c2, and the fusion protein was used to generate antibodies in rabbits. It was shown, with the aid of the polyclonal antiserum, that this viral protein was detectable at 24 h p.i. in infected cells. The protein appeared as an 82 kDa band in occlusion-derived virus and as an 82 kDa band and a 72 kDa band in budded virus. Amino acid sequence comparisons revealed that this ORF had high homology with the ORF p87 (77% similarity) of Orgyia pseudotsugata (Op) MNPV and the ORF p80 (60% similarity) of Autographa californica (Ac) MNPV. Immunoblots confirmed that the CfMNPV protein had antigenic similarities to the P87 protein of OpMNPV, but not to the P80 of AcMNPV.

Amino Acid Sequence↗

PubMed2005

Early and sustained expression of latent and host modulating genes in coordinated transcriptional program of KSHV productive primary infection of human primary endothelial cells.

Coordinated expression of viral genes in primary infection is essential for successful infection of host cells. We examined the expression profiles of Kaposi's sarcoma-associated herpesvirus (KSHV) transcripts in productive primary infection of primary human umbilical vein endothelial cells by whole-genome reverse-transcription real-time quantitative PCR. The latent transcripts were expressed early and sustained at high levels throughout the infection while the lytic transcripts were expressed in the order of immediate early, early, and lytic transcripts, all of which culminated before the production of infectious virions. Significantly, transcripts encoding genes with host modulating functions, including mitogenic and cell cycle-regulatory, immune-modulating, and anti-apoptotic genes, were expressed before those encoding viral structure and replication genes, and sustained at high levels throughout the infection, suggesting KSHV manipulation of host environment to facilitate infection. The KSHV transcriptional program in a primary infection defined in this study should provide a basis for further investigation of virus-cell interactions.

Apoptosis↗

PubMed1997

A novel Western blot test containing both viral and recombinant proteins for anticytomegalovirus immunoglobulin M detection.

We devised a novel Western blot (WB) test for anti-human cytomegalovirus (HCMV) immunoglobulin M (IgM) detection which contains viral structural polypeptides, significant portions of recombinant p150 (ppUL32), and a significant portion of the most immunogenic nonstructural protein p52 (ppUL44). This new test was evaluated in latently infected blood donors, pregnant women, and transplant recipients with ongoing HCMV infection and shown to be more sensitive and specific than traditional WB and conventional enzyme immunoassay for the detection of HCMV-specific IgM.

Adult↗

PubMed2001

African swine fever virus protein p54 interacts with the microtubular motor complex through direct binding to light-chain dynein.

Dynein is a minus-end-directed microtubule-associated motor protein involved in cargo transport in the cytoplasm. African swine fever virus (ASFV), a large DNA virus, hijacks the microtubule motor complex cellular transport machinery during virus infection of the cell through direct binding of virus protein p54 to the light chain of cytoplasmic dynein (LC8). Interaction of p54 and LC8 occurs both in vitro and in cells, and the two proteins colocalize at the microtubular organizing center during viral infection. p50/dynamitin, a dominant-negative inhibitor of dynein-dynactin function, impeded ASFV infection, suggesting an essential role for dynein during virus infection. A 13-amino-acid domain of p54 was sufficient for binding to LC8, an SQT motif within this domain being critical for this binding. Direct binding of a viral structural protein to LC8, a small molecule of the dynein motor complex, could constitute a molecular mechanism for microtubule-mediated virus transport.

African Swine Fever Virus↗

PubMed2002

Steatosis and liver cancer in transgenic mice expressing the structural and nonstructural proteins of hepatitis C virus.

BACKGROUND & AIMS: The aim of this study was to determine whether expression of hepatitis C virus proteins alters hepatic morphology or function in the absence of inflammation. METHODS: Transgenic C57BL/6 mice with liver-specific expression of RNA encoding the complete viral polyprotein (FL-N transgene) or viral structural proteins (S-N transgene) were compared with nontransgenic littermates for altered liver morphology and function. RESULTS: FL-N transcripts were detectable only by reverse-transcription polymerase chain reaction, and S-N transcripts were identified in Northern blots. The abundance of viral proteins was sufficient for detection only in S-N transgenic animals. There was no inflammation in transgenic livers, but mice expressing either transgene developed age-related hepatic steatosis that was more severe in males. Apoptotic or proliferating hepatocytes were not significantly increased. Hepatocellular adenoma or carcinoma developed in older male animals expressing either transgene, but their incidence reached statistical significance only in FL-N animals. Neither was ever observed in age-matched nontransgenic mice. CONCLUSIONS: Constitutive expression of viral proteins leads to common pathologic features of hepatitis C in the absence of specific anti-viral immune responses. Expression of the structural proteins enhances a low background of steatosis in C57BL/6 mice, while additional low level expression of nonstructural proteins increases the risk of cancer.

Animals↗

PubMed1990

Complete sequence of the genomic RNA of O'nyong-nyong virus and its use in the construction of alphavirus phylogenetic trees.

The alphaviruses are a group of about 25 positive-strand RNA viruses that are important human and veterinary pathogens and that are geographically dispersed. We report here the complete nucleotide sequence of the genomic RNA of the alphavirus, O'nyong-nyong virus. The RNA is 11,835 nucleotides in length and the organization of the genome is typical of alphaviruses. Phylogenetic trees were constructed from the protein sequences of O'nyong-nyong and six other alphaviruses. Trees were constructed for each nonstructural and structural viral protein individually in order to detect any possible recombination events, as well as to examine the differential divergence among the various proteins. The members of each tree can be divided into three subgroups: the Semliki Forest virus subgroup (Semliki Forest, O'nyong-nyong, and Ross River viruses), the eastern equine encephalitis virus subgroup (eastern equine encephalitis and Venezuelan equine encephalitis viruses), and the Sindbis virus subgroup. Sindbis virus, which is geographically restricted to the Old World, is more closely related to the eastern equine encephalitis subgroup, which are New World viruses, than it is to the Semliki Forest virus subgroup, which are mostly Old World viruses. Western equine encephalitis virus is a special case because it is a recombinant virus. Its nonstructural and capsid proteins are most closely related to those of eastern equine encephalitis virus while its glycoproteins are most closely related to those of Sindbis virus. All members of a given subgroup have diverged the same amount from their common node point. However, the structural proteins of the Semliki Forest virus subgroup are more closely related to one another than those of the eastern equine encephalitis virus subgroup. This difference probably indicates that the members of the eastern equine encephalitis virus subgroup diverged earlier than the members of the Semliki Forest virus subgroup, which suggests that the alphaviruses originated in the New World.

Alphavirus↗

PubMed1989

Characterization of a temperature sensitive feline infectious peritonitis coronavirus.

The characteristics of a temperature sensitive feline infectious peritonitis virus (TS-FIPV) were examined. TS-FIPV, unlike its parent strain, DF2 wild type FIPV (WT-FIPV), propagated at 31 degrees C (permissive temperature) but not at 39 degrees C (nonpermissive temperature). This temperature preference of TS-FIPV was also demonstrated in cats by the ability of the virus to replicate only at the lower temperature in the upper respiratory tract and not at systemic sites where higher temperatures (38-39 degrees C) prevail. Viral structural proteins and RNA were synthesized at 39 degrees C but some undefined maturational defect prevented the formation of infectious TS-FIPV at its nonpermissive temperature. TS-FIPV was more thermolabile than WT-FIPV which indicated alterations in the structural proteins of TS-FIPV, and a difference in the envelope protein of the two viruses was revealed by Western blot analysis. Plaque assay characterization showed that TS-FIPV produced small plaques in comparison to the large plaques of WT-FIPV. These unique characteristics possessed by TS-FIPV may account for its nonvirulent nature and ability to stimulate protective immune responses in cats.

Animals↗

PubMed1995

Intermolecular binding sites of human immunodeficiency virus type 1 Rev protein determined by protein footprinting.

Human immunodeficiency virus encodes the regulatory protein Rev, which is required for expression of viral structural proteins. It binds to an RNA element (RRE) in the viral transcript and up-regulates the cytoplasmic appearance of unspliced and singly spliced viral mRNA. We have studied the structure of Rev alone and complexed with the RRE and two monoclonal antibodies, using a protein footprinting approach. The method involves radioactive labeling at the C-terminal end of Rev fusion protein followed by limited proteolysis under native conditions, using 10 different proteinases. Rev protein was mainly cleaved within the basic domain and in the C-terminal part. The periodicity of the proteolytic cleavages within the basic domain strongly suggests that it forms an alpha-helical structure with one side facing the solvent. In the presence of RRE, these cleavages became significantly reduced. In addition, strong protection was observed at position 66 outside the basic domain. As a control for the specificity of the footprinting reaction, we confirmed the position of the epitopes for two monoclonal antibodies. This protein footprinting methodology is generally applicable to other proteins for which terminal modifications are acceptable, and provides a useful tool for mapping structure, substrate binding, and conformational changes.

Base Sequence↗

PubMed1997

Novobiocin inhibits vaccinia virus replication by blocking virus assembly.

Novobiocin inhibits the replication of vaccinia virus in cultured BSC40 cells. All classes of viral proteins were synthesized during synchronous infection in the presence of drug. The onset of DNA replication was delayed slightly, yet the extent of DNA replication in the presence of novobiocin was comparable to that of a control infection. A delay in the temporal transition to late viral protein synthesis was in keeping with the effects on DNA replication. Although the precursor forms of the major viral structural proteins were synthesized normally at late times, the proteolytic processing of these polypeptides was inhibited, which suggested an impediment to virus assembly. Electron microscopy revealed that novobiocin blocked virus morphogenesis at an early stage. Conversion of the concatemeric DNA replication intermediates into hairpin telomeres occurred in the presence of novobiocin, confirming that telomere resolution was not coupled to virus assembly. Novobiocin is the latest addition to a class of antipoxviral agents, which includes rifampin and IMCBH, that arrest morphogenesis.

Animals↗

PubMed2000

Identification of a novel RNA splicing pattern as a basis of restricted cell tropism of erythrovirus B19.

Prior studies on the transcription of erythrovirus B19 have identified a short leader sequence associated with all spliced viral transcripts. While some variability has been observed in the acceptor for this first intron, studies to date in both permissive and nonpermissive cell types have reported a unique splice donor site. In the semipermissive MB-02 cell line, we have found that splicing of this first intron proceeds almost exclusively via a cryptic CT donor downstream of the previously reported GT donor at nucleotide 406. The resulting messages for the viral structural proteins and 11-kDa protein are thereby made bicistronic, with the first expressible polypeptide being a 34 amino acid fusion of the NS-1 and 7.5-kDa proteins. The presence of an upstream open-reading frame on these messages is likely to block effective translation of the downstream structural protein products. We propose this as a significant mechanism in determining B19's tropism on the basis of host cell splicing machinery, and present evidence in support of this model. Additionally, this is the first report of usage of a noncanonical splice donor in B19, and to our knowledge the first report of a CT-AG splice in any system.

Alternative Splicing↗