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Virology Jun 1998Toscana (TOS) virus stocks strongly interfering with standard virus replication were obtained by sequential passages of virus in suckling mouse brain. Characterization...
Toscana (TOS) virus stocks strongly interfering with standard virus replication were obtained by sequential passages of virus in suckling mouse brain. Characterization of viral RNAs in these stocks showed the presence of a heterogeneous population of defective RNA molecules derived from the L genomic segment, in both nucleocapsid (NC) and messenger RNAs, suggesting that these molecules could be replicated, assembled, and transcribed. Subgenomic RNAs from the L segment but not from the S or M segments were found in cells infected with these stocks. Defective RNA molecules interfered with virus replication and retained 5' and 3' genomic termini. Nucleotide sequence analysis of some cloned defective interfering (DI) RNAs revealed they contained one or more internal deletions reducing their length to 7-13% of the full-length L segment. An identical sequence motif, of variable length, was found at both terminal sites of the RNA junction on standard L sequences. This motif was retained only in one copy in the subgenomic RNA. These results are consistent with the generation of TOS virus DI particles in vivo and suggest that the defective genomic RNAs could be generated by polymerase jumping from a sequence to an identical one spatially closed because of the RNA structure.
Topics: Animals; Animals, Suckling; Brain; Chlorocebus aethiops; Cloning, Molecular; Defective Viruses; Mice; Molecular Sequence Data; Phlebovirus; RNA, Messenger; RNA, Viral; Sequence Analysis, DNA; Sequence Deletion; Serial Passage; Vero Cells; Viral Plaque Assay; Virus Replication
PubMed: 9657000
DOI: 10.1006/viro.1998.9195 -
Current Topics in Microbiology and... 2012Virus-like particles are a new type of vaccine platform that presents an attractive alternative to more traditional live-attenuated or inactivated/subunit vaccines.... (Review)
Review
Virus-like particles are a new type of vaccine platform that presents an attractive alternative to more traditional live-attenuated or inactivated/subunit vaccines. Virus-like particles (VLP) are composed of viral structural proteins that assemble spontaneously in cells, mimicking the live virus without the possibility of replication. They are readily recognized by the immune system, inducing both humoral and cellular immune responses. Here we review the development of VLP as vaccine delivery systems at mucosal surfaces. We first summarize the current status of VLP vaccines in general, and then discuss their use in mucosal vaccination approaches for several viruses that enter the host via the urogenital, respiratory or gastrointestinal tract.
Topics: Animals; Antigens; Defective Viruses; Drug Delivery Systems; Humans; Mucous Membrane; Vaccination
PubMed: 21744306
DOI: 10.1007/82_2011_135 -
The Journal of General Virology Jan 1992Viral protein and RNA synthesis were compared in BHK and Aedes albopictus C6/36 (mosquito) cells infected with Bunyamwera virus. In BHK cells host protein synthesis was... (Comparative Study)
Comparative Study
Viral protein and RNA synthesis were compared in BHK and Aedes albopictus C6/36 (mosquito) cells infected with Bunyamwera virus. In BHK cells host protein synthesis was inhibited and viral proteins were detected until the cells died; in C6/36 cells there was little inhibition of host proteins and viral proteins could not be detected after 36 h post-infection. Relatively more S segment RNA than L or M segment RNA was produced in infected C6/36 cells compared to BHK cells. A persistent infection of C6/36 cells was established and the cells were passaged at weekly intervals for over a year. The titre of virus released from the cells and the level of viral RNA in the cells at different passages fluctuated markedly, but there was no simple relationship between virus titre and the amount of viral RNA. Northern blot analysis of viral RNA extracted from persistently infected cells revealed the presence of subgenomic RNAs derived from the L RNA segment. These defective RNAs were not packaged into nucleocapsids. The presence of the defective RNAs did not correlate with resistance of cells cloned from the persistently infected population to superinfection with homologous virus. Hence the role of these defective RNAs in the maintenance of the persistent state remains to be elucidated.
Topics: Animals; Blotting, Northern; Bunyamwera virus; Cell Line; Culicidae; Defective Viruses; RNA, Viral; Viral Proteins; Virus Replication
PubMed: 1346156
DOI: 10.1099/0022-1317-73-1-53 -
Clinical Microbiology and Infection :... Sep 2002Herpes simplex virus-1 (HSV-1) is a relatively large double-stranded DNA virus encoding at least 89 proteins with well characterized disease pathology. An understanding... (Review)
Review
Herpes simplex virus-1 (HSV-1) is a relatively large double-stranded DNA virus encoding at least 89 proteins with well characterized disease pathology. An understanding of the functions of viral proteins together with the ability to genetically engineer specific viral mutants has led to the development of attenuated HSV-1 for gene therapy. This review highlights the progress in creating attenuated genetically engineered HSV-1 mutants that are either replication competent (viral non-essential gene deleted) or replication defective (viral essential gene deleted). The choice between a replication-competent or -defective virus is based on the end-goal of the therapeutic intervention. Replication-competent HSV-1 mutants have primarily been employed as antitumor oncolytic viruses, with the lytic nature of the virus harnessed to destroy tumor cells selectively. In replacement gene therapy, replication-defective viruses have been utilized as delivery vectors. The advantages of HSV-1 vectors are that they infect quiescent and dividing cells efficiently and can encode for relatively large transgenes.
Topics: Antineoplastic Agents; Clinical Trials, Phase I as Topic; Combined Modality Therapy; Defective Viruses; Gene Transfer Techniques; Genetic Therapy; Genetic Vectors; Humans; Neoplasms; Simplexvirus; Transcription, Genetic; Virus Replication
PubMed: 12427216
DOI: 10.1046/j.1469-0691.2002.00432.x -
Molecular Biotechnology Oct 1994Herpes simplex virus (HSV) has a number of advantages as a vector for delivering specific genes to the nervous system. These include its large size, wide host range, and... (Review)
Review
Herpes simplex virus (HSV) has a number of advantages as a vector for delivering specific genes to the nervous system. These include its large size, wide host range, and its ability to establish long-lived asymptomatic infections in neuronal cells in which a specific region of the viral genome continues to be expressed. Unfortunately, the large size of this virus and difficulty in manipulating it has led to its use as a vector lagging behind that of other, smaller viruses such as the retroviruses. In addition, the virus's ability to replicate lytically in the brain, under some circumstances, causing encephalitis, has led to fears about its potential safety for ultimate use in humans. This review will discuss a number of new approaches that are aimed at rendering simpler the insertion of foreign genes into the virus and making it as safe as possible. Ultimately, these advances offer real hope for the use of HSV vectors in gene therapy procedures.
Topics: Brain; Brain Diseases; Cloning, Molecular; DNA, Recombinant; Defective Viruses; Gene Expression Regulation, Viral; Genetic Therapy; Genetic Vectors; Genome, Viral; Humans; Safety; Simplexvirus; Virus Latency; Virus Replication
PubMed: 7866875
DOI: 10.1007/BF02824809 -
Current Protocols in Human Genetics Aug 2002Advances in identification and characterization of gene products responsible for specific diseases of the nervous system have opened opportunities for novel therapies...
Advances in identification and characterization of gene products responsible for specific diseases of the nervous system have opened opportunities for novel therapies using gene transfer vectors for gene replacement. Herpes simplex virus (HSV)-based vectors are particularly well suited for gene delivery to neurons of the central and peripheral nervous systems. The authors have developed methods to delete HSV-1 IE gene functions and to subsequently introduce foreign genes into the HSV-1 genome using homologous recombination. This unit describes methods for generating cell lines that complement multiple essential gene deletion mutants as well for generating such replication-defective virus recombinants and inserting foreign DNA sequences into replication-defective viral genomes, the last step in preparing a vector. Three support protocols describe methods for preparing virus stocks, titering virus, and preparing viral DNA.
Topics: Animals; Cell Line; Chlorocebus aethiops; DNA Primers; Defective Viruses; Gene Transfer Techniques; Genes, Immediate-Early; Genetic Complementation Test; Genetic Vectors; Genetics, Medical; Herpesvirus 1, Human; Humans; Neurons; Polymerase Chain Reaction; Vero Cells
PubMed: 18428322
DOI: 10.1002/0471142905.hg1211s33 -
Virology Nov 1974
Topics: Animals; Cell Line; Cytopathogenic Effect, Viral; DNA Replication; DNA, Viral; Defective Viruses; Endonucleases; Fluorescent Antibody Technique; Genetic Complementation Test; Haplorhini; Helper Viruses; Kidney; Mutation; Simian virus 40; Temperature; Thymidine; Tritium; Viral Plaque Assay
PubMed: 4370797
DOI: 10.1016/0042-6822(74)90307-9 -
Virology Feb 1984Vaccinia virus particles formed in interferon-treated, infected cells have been isolated. These particles have been characterized with regard to polypeptide composition,...
Vaccinia virus particles formed in interferon-treated, infected cells have been isolated. These particles have been characterized with regard to polypeptide composition, and ability to adsorb, penetrate, uncoat, and synthesize proteins in infected cells. As determined by one-dimensional SDS-PAGE analysis, with interferon concentrations of 100-500 u/ml, the pattern of [35S]methionine-labeled virion proteins was not altered; higher doses of interferon resulted in decreased labeling of some proteins. However, interferon doses of 100-500 u/ml decreased phosphorylation of vaccinia virus basic core polypeptide (P-11) by 30-70%; the same doses of interferon decreased the labeling of virus glycoproteins by 40-80%. Virus purified from interferon-treated cells adsorb, penetrate, and uncoat to a lesser extent than virus control. During infection to cells, these virus particles caused shutoff and synthesized the same spectrum of viral proteins as normal virus. These findings show that there are protein alterations in vaccinia virus particles isolated from interferon-treated, infected cells. These alterations may contribute to limit the spread of virus infection.
Topics: Animals; Defective Viruses; Interferon Type I; L Cells; Mice; Protein Biosynthesis; Vaccinia virus; Viral Proteins
PubMed: 6702105
DOI: 10.1016/0042-6822(84)90443-4 -
Virus Research Feb 2016Like many other viral pathogens, influenza A viruses can form defective interfering particles (DIPs). These particles carry a large internal deletion in at least one of...
Like many other viral pathogens, influenza A viruses can form defective interfering particles (DIPs). These particles carry a large internal deletion in at least one of their genome segments. Thus, their replication depends on the co-infection of cells by standard viruses (STVs), which supply the viral protein(s) encoded by the defective segment. However, DIPs also interfere with STV replication at the molecular level and, despite considerable research efforts, the mechanism of this interference remains largely elusive. Here, we present a mechanistic mathematical model for the intracellular replication of DIPs. In this model, we account for the common hypothesis that defective interfering RNAs (DI RNAs) possess a replication advantage over full-length (FL) RNAs due to their reduced length. By this means, the model captures experimental data from yield reduction assays and from studies testing different co-infection timings. In addition, our model predicts that one important aspect of interference is the competition for viral proteins, namely the heterotrimeric viral RNA-dependent RNA polymerase (RdRp) and the viral nucleoprotein (NP), which are needed for encapsidation of naked viral RNA. Moreover, we find that there may be an optimum for both the DI RNA synthesis rate and the time point of successive co-infection of a cell by DIPs and STVs. Comparing simulations for the growth of DIPs with a deletion in different genome segments suggests that DI RNAs derived from segments which encode for the polymerase subunits are more competitive than others. Overall, our model, thus, helps to elucidate the interference mechanism of DI RNAs and provides a novel hypothesis why DI RNAs derived from the polymerase-encoding segments are more abundant in DIP preparations.
Topics: Defective Viruses; Influenza A virus; Models, Theoretical; RNA, Viral; Virus Replication
PubMed: 26592173
DOI: 10.1016/j.virusres.2015.11.016 -
Journal of Virology Apr 1979Serial undiluted passage of Semliki Forest virus in a clone of Aedes albopictus cells resulted in a marked decrease in infectious virus yields due to the generation and...
Serial undiluted passage of Semliki Forest virus in a clone of Aedes albopictus cells resulted in a marked decrease in infectious virus yields due to the generation and accumulation of defective interfering particles. Virus from the third passage had a high particle/infectivity ratio and interfered specifically with homologous but not heterologous standard virus replication. Two RNA species of molecular weights 0.78 X 10(6) and 0.61 X 10(6) were the major RNA components of purified passage 4 virus. These RNA species were also the predominant virus RNA species detected in cells infected with passage 3 virus. Synthesis of standard virus RNA and virus-specified protein was much reduced in passage 3 virus-infected cells. Interference with standard virus replication and the synthesis of large amounts of defective interfering RNA were also observed in chicken embryo cells infected with passage 3 virus from mosquito cells.
Topics: Aedes; Animals; Cell Line; Clone Cells; Defective Viruses; Peptides; RNA, Viral; Semliki forest virus; Viral Interference; Viral Proteins; Virus Replication
PubMed: 480458
DOI: 10.1128/JVI.30.1.38-44.1979