A self-cleaving hammerhead ribozyme gene containing a 14nt target sequence of ASSVd at the 3' end of hammerhead ribozyme was synthesized, amplified and cloned at the Xho I-Hind III site of pGEM7Zf(+). The ends produced by Xho I or Sal I can link together, thus the recognition sites of both enzymes vanish and can't be cut by either one. We used this property to get the recombinant plasmid bearing 2, 4, 6, 8, 10 and 12 copies of self-cleavable ribozyme respectively after successively sub-cloning five times. Linearized recombinat plasmid model catalyzed by T7 RNA polymerase was transcribed in vitro. The multimeric ribozyme molecules efficiently self-cleaved via cis-acting to release many ribozyme molecules It indicates that the concentration of ribozyme transcripts has been enhanced during transcription. Trans-cleavage reaction was carried out by incubating monomeric and multimeric ribozymes with same mol concentration and 32P labeled target ASSVd. Both ribozymes and target transcripts were mixed in 1:1 ratio. Autoradiograms showed the transcripts of multimeric ribozyme were substantially more effective against the ASSVd target RNA than the monomeric ribozymes. We confer that the multimeric self-clevable ribozyme is likely to provide more valuable application in vivo.
Malus ; virology ; RNA, Catalytic ; chemistry ; genetics ; metabolism ; RNA, Viral ; metabolism ; Viroids ; metabolism

OBJECTIVETo study the relativity between La protein and the stability of HBV mRNA and the expression of HBV protein.

METHODSFour specific siRNAs were obtained by transcription in vitro. After transfection with the siRNAs into HepG2.2.15 cells for 3 days, the inhibitive effects of La protein were analyzed by Western blot; the content changes of HBsAg, HBeAg and HBV-DNA were detected by ECL and RT-PCR.

RESULTSIn comparison to normal cells, La protein was less in the cells. There was less La protein in the cells trans-infected with siRNAs. HBsAg, the HBeAg and HBV-DNA secreted by the cells transfected with siRNA were also less than that in the normal cells.

CONCLUSIONThere is a correlation between La protein and HBV mRNA and the expression of HBV protein.

Autoantigens ; metabolism ; Cell Line, Tumor ; DNA, Viral ; Hepatitis B Surface Antigens ; Hepatitis B virus ; genetics ; metabolism ; Humans ; RNA, Messenger ; genetics ; metabolism ; RNA, Small Interfering ; RNA, Viral ; Ribonucleoproteins ; metabolism

OBJECTIVETo screen cellular proteins binding to the core region of hepatitis C virus (HCV) from human hepatoma cells.

METHODSUnlabeled and labeled RNA transcripts were prepared by in vitro transcription. Cytoplasmic extracts were prepared from human hepatoma cells HepG2. Ultraviolet (UV) cross-linking was used to screen the cellular proteins that would bind to the core region of HCV. Competition experiment was performed to confirm the specificity of the binding in which excess unlabeled RNA of HCV core region and plasmid RNA were used as competitors.

RESULTSTwo cellular proteins of 6.6 x 10(4) and 5.5 x 10(4) were found binding to the core region of HCV RNA by UV cross-linking assay. The unlabeled core region of HCV RNA could compete out this binding whereas the unlabeled plasmid RNA could not.

CONCLUSIONThe cellular proteins from HepG2 cells could bind to the core region of HCV RNA.

Binding Sites ; Cross-Linking Reagents ; chemistry ; Hepacivirus ; genetics ; metabolism ; RNA, Viral ; genetics ; metabolism ; Ultraviolet Rays ; Viral Core Proteins ; genetics ; metabolism

Since Epstein Barr virus was shown to encode microRNAs(miRNAs) in 2004, more than 470 miRNAs have been discovered in α-, β-, and γ-herpesviruses. MiRNAs are small non-coding RNA molecules and generally only have 18-25 nucleotides in length, which can regulate the expression of target genes by targeting its transcripts. Herpesvirus-encoded miRNAs not only target the key genes from latency to lytic replication, but also regulate various host cellular genes. Current data manifest that herpesvirus-encoded miRNAs can regulate viral latent infection and lytic replication, immune recognition, apoptosis, and tumorigenesis. The purpose of this paper is to summarize the targets and their fuction of hepesvirus-encoded miRNAs, in order to provide theoretical support for further analysis herpesviral pathogenesis.
Animals ; Herpesviridae ; genetics ; metabolism ; Herpesviridae Infections ; virology ; Humans ; MicroRNAs ; genetics ; metabolism ; RNA, Viral ; genetics ; metabolism

The zinc-finger antiviral protein (ZAP) is a host factor that specifically inhibits the replication of certain viruses by eliminating viral mRNAs in the cytoplasm. In previous studies, we demonstrated that ZAP directly binds to the viral mRNAs and recruits the RNA exosome to degrade the target RNA. In this article, we provide evidence that a DEXH box RNA helicase, DHX30, is required for optimal antiviral activity of ZAP. Pull-down and co-immunoprecipitation assays demonstrated that DHX30 and ZAP interacted with each other via their N terminal domains. Downregulation of DHX30 with shRNAs reduced ZAP's antiviral activity. These data implicate that DHX30 is a cellular factor involved in the antiviral function of ZAP.
Cytoplasm ; metabolism ; physiology ; DEAD-box RNA Helicases ; metabolism ; Humans ; Immunoprecipitation ; Protein Binding ; physiology ; RNA ; metabolism ; physiology ; RNA Helicases ; metabolism ; physiology ; RNA, Messenger ; metabolism ; physiology ; RNA, Viral ; metabolism ; RNA-Binding Proteins ; metabolism

HBV infections leads to severe public health problems around the world, especially in China. Improved understanding of the molecular mechanisms of HBV reverse transcription is fundamental for optimization of treatment and solution to drug-resistance. Recently, the main structural basis involved in the process of HBV reverse transcription and the cis-elements were revealed by means of biochemistry and genetics. The entire process of reverse transcription is completed mainly through the first template switch mediated by the P- epsilon structure; the second template switch mediated by 5E/3E and M structure; and the third template switch mediated by 5' r / 3' r structure. The important structure and the cis-elements involved in this process are the focus of this review, at the same time, an overview of the progress in relevent studies is demonstrated to show the whole picture of the HBV reverse process.
Animals ; Hepatitis B ; virology ; Hepatitis B virus ; enzymology ; genetics ; metabolism ; Humans ; RNA, Viral ; genetics ; RNA-Directed DNA Polymerase ; genetics ; metabolism ; Reverse Transcription ; Viral Proteins ; genetics ; metabolism

Porcine endogenous retroviruses (PERVs) are members of family Retroviridae, genus Gamma retrovirus, and transmitted by both horizontally and vertically like other endogenous retroviruses (ERVs). PERV was initially described in the 1970s having inserted its gene in the host genome of different pig breeds, and three classes, PERV-A, PERV-B, and PERV-C are known. The therapeutic use of living cells, tissues, and organs from animals called xenotransplantation might relieve the limited supply of allografts in the treatment of organ dysfunction. Because of ethical considerations, compatible organ sizes, and physiology, the pig has been regarded as an alternative source for xenotransplantation. Sensitive duplex reverse transcription-polymerase chain reaction protocols for simultaneously detecting PERV gag mRNA and porcine glyceraldehydes 3-phosphate dehydrogenase mRNA in one tube was established. To compare the age-related PERV expression patterns of the lung, liver, spleen, kidney, heart, and pancreas in commercial pigs, 20 pigs from four age groups (5 heads each in 10 days-, 40 days-, 70 days-, and 110 days-old, respectively) were used in this study. The expression patterns of PERV were statistically different among age groups in lung, liver, and kidney (ANOVA, p<0.05). These data may support in the selection of appropriate donor pigs expressing low levels of PERV mRNA.
Animals ; Endogenous Retroviruses/*metabolism ; Gene Expression Regulation, Viral/*physiology ; RNA, Messenger/genetics/metabolism ; RNA, Viral/genetics/metabolism ; Reverse Transcriptase Polymerase Chain Reaction/methods/*veterinary ; Sensitivity and Specificity ; Swine/*virology

Influenza C virus is an important respiratory pathogen not only infecting people, but also pigs, dogs, and other animals. Polymerase is central to the replication of influenza C virus and is an important target for studying the mechanism of viral replication. However, there is no commercial monoclonal antibody (MAb) targeting influenza C virus polymerase, which hampers the development of relevant research to some extent. In order to prepare MAb targeting the polymerase basic protein 2 (PB2) of influenza C virus, influenza C virus RNA-dependent RNA polymerase (RdRp, consists of PB1, PB2 and P3) was co-immunoprecipitated with Flag-tagged human acidic nuclear phosphoprotein 32A (huANP32A-Flag) from 293T cells based on the interaction between huANP32A and influenza virus RdRp. The purified RdRp was used as antigen to immunize BALB/c mice. Six positive hybridoma cell lines (7B11-5, 8A4-5, 13D9-6, 8D4-1, 8D4-3, 9F9-4) that stably secrete and recognize PB2 MAb were screened by indirect ELISA and Western blotting. The subtypes of MAb 7B11-5, 8A4-5, 8D4-1 and 8D4-3 antibody were identified as IgG1, the subtypes of MAb 13D9-6 and 9F9-4 were IgG2a and IgG3, respectively. All the light chains of the MAbs were κ chain. A hybridoma cell line 8D4-1 with high titer was further selected to prepare ascites. The titer of mouse ascites antibody was determined to be 1:64 000. Western blotting results showed that the MAb 8D4-1 had a specific immune response with ICV PB2; laser confocal assay showed that the prepared MAb 8D4-1 accurately detected the subcellular localization of PB2 subunits. Moreover, ICV RdRp was highly enriched by ANP32A. The high specific of the prepared PB2 MAb 8D4-1 may facilitate the polymerase detection, structural analysis and mechanism study of influenza C virus.
Animals ; Antibodies, Monoclonal/metabolism* ; Ascites ; Humans ; Influenzavirus C/metabolism* ; Mice ; Nuclear Proteins/metabolism* ; RNA-Binding Proteins ; RNA-Dependent RNA Polymerase/genetics* ; Viral Proteins/metabolism* ; Virus Replication

OBJECTIVETo explore the possibility of transacting hepatitis D virus (HDV) ribozyme cleaving in vitro the hepatitis B virus (HBV) mRNA fragments.

METHODSAccording to the established pseudoknot-like structure, its' H1 domain was changed to design the transacting HDV ribozyme Rc1 and Rc2, which targeted the 701-713 site and 776-788 site of HBV C domain. After the chemically synthesised cDNA of the ribozyme was cloned into the vector PGEM-4Z, the transacting HDV ribozyme was transcriped using in vitro transcription technology. The in vitro cleavage characteristics of the ribozyme were studied and the kinetic parameters (Kcat and Km) were determined by Eadie Hofstee plotting.

RESULTSBoth the two ribozymes had the ability to cleave the substrate, the cleavage percentage at 37 degrees for 90 minutes were 50% and 51%. According to the Eadie Hofstee plot, the Km of the Rc1 and Rc2 were 0.61 micromol and 0.58 micromol, the Kcat were 0.64 x min(-1) and 0.60 x min(-1),respectively.

CONCLUSIONSThe cleaving ability of trans-acting HDV ribozyme on non-HDV RNA fragment was tested. The results showed a new potential of the antisense antisense regent for HBV gene therapy.

DNA, Antisense ; genetics ; Genome, Viral ; Hepatitis B virus ; genetics ; Hepatitis Delta Virus ; enzymology ; genetics ; Humans ; RNA, Catalytic ; genetics ; metabolism ; RNA, Messenger ; genetics ; RNA, Viral ; genetics ; Transcription, Genetic

Hepatitis C virus (HCV) is a positive sense, single-stranded RNA virus in the Flaviviridae family. It causes acute hepatitis with a high propensity for chronic infection. Chronic HCV infection can progress to severe liver disease including cirrhosis and hepatocellular carcinoma. In the last decade, our basic understanding of HCV virology and life cycle has advanced greatly with the development of HCV cell culture and replication systems. Our ability to treat HCV infection has also been improved with the combined use of interferon, ribavirin and small molecule inhibitors of the virally encoded NS3/4A protease, although better therapeutic options are needed with greater antiviral efficacy and less toxicity. In this article, we review various aspects of HCV life cycle including viral attachment, entry, fusion, viral RNA translation, posttranslational processing, HCV replication, viral assembly and release. Each of these steps provides potential targets for novel antiviral therapeutics to cure HCV infection and prevent the adverse consequences of progressive liver disease.
Antigens, CD81/metabolism ; Genome, Viral ; Hepacivirus/genetics/*physiology ; Humans ; RNA, Viral/metabolism ; Scavenger Receptors, Class B/metabolism ; Viral Envelope Proteins/chemistry/metabolism ; Viral Nonstructural Proteins/chemistry/metabolism ; Virus Assembly ; Virus Internalization ; Virus Replication