The E2 envelope glycoprotein of virulent Shimen strain and avirulent C-strain of Classical swine fever virus (CSFV) has 5 and 6 potential glycosylation sites, respectively, and the potential glycosylation site 986N is unique to C-strain. To study the differences in glycosylation between the virus pair, the E2 genes (removing signal sequence and transmembrane anchor regions) of the two strains fused with the melittin signal sequence were expressed in the Sf9 insect cells. The recombinant E2 proteins were secreted into the medium of Sf9 cells in dimer form with different molecular weight (MW). Deglycosylation of the recombinant E2 proteins by endo H and PNGase F showed that the deglycosalated Shimen-E2 and HCLV-E2 have the same MW, indicating that the different MW between Shimen-E2 and HCLV-E2 proteins came from different glycosylation. Site-directed mutagenesis in the potential glycosylation site at 986N demonstrated that the mutated Shimen-E2 protein had the same MW as the wild-type HCLV-E2 protein, while the mutated HCLV-E2 had the same MW as the wild-type Shimen-E2 protein. We suggest that the different MW between Shimen-E2 and HCLV-E2 is resulted from the different glycosylation on 986 N glycosylation site.
Baculoviridae ; genetics ; Blotting, Western ; Classical swine fever virus ; chemistry ; classification ; Glycosylation ; Molecular Weight ; Mutation ; Recombinant Proteins ; chemistry ; Viral Envelope Proteins ; chemistry ; Virulence

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

OBJECTIVETo secreted express envelope glycoprotein (E) of dengue virus type 2 extracellularly.

METHODSThe entire prM/E gene was amplified by RT-PCR. An optimized signal sequence gene from Japanese encephalits virus (JEV, SA14-14-2 strain) was introduced using fusion PCR. The impact of E protein transmembrane and cytoplasmatic domains was compared by amplifying prM and E with full length of E gene, with 20% truncation of the E gene at 3' terminus and one chimeric gene, which was generated by replacing the 3' terminal 20% region of E gene with the corresponding sequence of JEV (SA14-14-2 strain). The PCR segments were inserted into the NheI and NotI sites of pcDNA5/FRT vector or into the NheI and XhoI sites of pAcUW51-M. Then they were transfected into 293T cells or Sf9 cells respectively. The expression and secretion of E protein were detected by immunofluorescence assay (IFA) and Western Blot.

RESULTSAfter transected into 293T cells or Sf9 cells, all constructs expressed E protein intracellularly indentified by IFA while only two plasmids could secret detectable E protein into tissue culture using Western Blot analysis.

CONCLUSIONSignal peptide as well as the transmembrane and cytoplasmatic domains is crucial for the secretion of dengue E protein.

Animals ; Cell Line ; Dengue ; metabolism ; virology ; Dengue Virus ; genetics ; metabolism ; Gene Expression ; Humans ; Protein Structure, Tertiary ; Protein Transport ; Spodoptera ; Viral Envelope Proteins ; chemistry ; genetics ; metabolism

This paper investigated the envelope protein E1/E2 quasispecies genetic characterization of 4 HCV positive sera (Genotype 1b: 274, 366, 383; Genotype 2a: 283) in China. Nucleotide acid was extracted and glycoprotein E1/E2 (191-764aa) coding genes were obtained by RT-PCR, positive clones were randomly selected for sequencing. The phylogenetic relationships and the homology of nucleotide and amino acid were analyzed based on E1/E2 coding genes, and some vital functional regions of E1/E2 were characterized. A total of 43 sequences (274: 10; 283: 12; 366: 13; 383: 8) were obtained showing high genetic heterogeneity in HVR1 and HVR2 regions, while sequences of the neutralizing epitopes, transmembrane domain I, II and N-terminal ectodomain were comparatively conservative. Single base (C) insertion mutation at nt1279 ( E1 region, aa313), resulting in a mutated E1 coding protein (beginning at aa 313) and interruption at N terminus (aa 398) of HVR1 region of E2, was dominant quasispecies sequence(11/12) found in serum 283 . This is the first report on E1/E2 quasispecies in Chinese HCV patients and this novel pattern of insertion mutation provides important information for further study on HCV pathogenesis and immune evasion.
Amino Acid Sequence ; Base Sequence ; DNA Mutational Analysis ; Hepacivirus ; genetics ; pathogenicity ; Hepatitis C ; virology ; Humans ; Molecular Sequence Data ; Mutagenesis, Insertional ; Viral Envelope Proteins ; chemistry ; genetics

To analyze the genetic characterization of epidemic rubella virus strains isolated in Liaoning from 2007-2012, a total of 145 rubella virus strains were isolated using Vero/Slam cell line from the patients' throat swabs during rubella outbreaks and sporadics cases in Liaoning Province from 2007 to 2012. Fragments of 945 nucleotides containing 1E gene from 145 rubella virus isolates were amplified by RT-PCR, the PCR products were sequenced and analyzed. Based on the 739 nucleotides of 1E gene, the phylogenetic trees were constructed with 32 WHO rubella reference strains of 13 genotypes downloaded from GenBank and 145 rubella virus strains. The results showed that the 145 rubella virus strains in 2007 -2012 belonged to genotype 1E, nucleotide acids and amino acids similarities were 97.2%-100.0% and 97.6%-100.0%, respectively. Compared to the 1E reference strains(Rvi/ Dezhou.CHN/02, RVi/MYS/01), the nucleotide acids and amino acids similarities were 96.6%-99.2% and 98.2%-100.0%, respectively except for one amino acid change (Val246-Ala246) of RVi/Shenyang. Liaoning. CHN/13.11/13, and Asp262-Asn262 of RVi/Shenyang. Liaoning. CHN/13.11/4 and RVi/Liaoyang. Liaoning. CHN/26. 11/2. there had no change found in the important antigenic epitope sites, the hemagglutination inhibition and neutralization epitopes of the other rubella viruses. All the 145 strains isolated had the same amino acid change (Leu338--Phe338) in E1 protein. These findings suggested that genotype 1E of rubella virus was the predominant genotype in Liaoning province. the rubella prevailed in recent six years was mainly caused by rubella viruses genotype 1E with multi-transmission routes.
Amino Acid Sequence ; China ; epidemiology ; Epidemics ; Genotype ; Humans ; Molecular Sequence Data ; Phylogeny ; Rubella ; epidemiology ; virology ; Rubella virus ; classification ; genetics ; isolation & purification ; Sequence Alignment ; Viral Envelope Proteins ; chemistry ; genetics

In this study, Recombinant baculoviruses rBac-NF and rBac-NG were generated for expressing F and G proteins Nipah virus (NiV) . The expression of recommbinant G (rNG) and F (rNF) protein in rBac-NF and rBac-NG infected cells were confirmed by western-blot. Both rNG and rNF showed sensitive and specific antigenic reaction to rabbit serum anti-Nipah virus in indirect immunofluorescence detection and indirect ELISA. Immunization with rBac-NF and rBac-NG infected insect cells elicited G ad F protein specific antibody responses in mice. Furthermore, the G ad F specific antibodies could neutralize the infectivity of the VSVdeltaG* F/G, the NiV F and G envelope glycoproteins psudotyped recombinant Vesicular Stomatitis Virus expressing green fluorescence protein. The results demonstrated F and G protein expressed by the recombinant baculoviruses could be safe economic diagnostic antigens for the surveillance and monitoring of NiV and promising subunit vaccines for the prevention of NiV.
Animals ; Antigens, Viral ; immunology ; Baculoviridae ; genetics ; metabolism ; Mice ; Mice, Inbred BALB C ; Nipah Virus ; chemistry ; genetics ; Rabbits ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; immunology ; Recombination, Genetic ; Viral Envelope Proteins ; biosynthesis ; genetics ; immunology

OBJECTIVETo understand the molecular mechanisms of hantavirus assembly and maturation by stably expressing the intracellular antibodies to hantavirus glycoprotein G1 and G2 in endoplasmic reticulum (ER) and cytoplasm (Cyto) of Vero E6 cell.

METHODSThe genes of VH and VL of antibodies against glycoprotein of hantavirus were amplified by PCR and cloned into pOPE 101-215 (Yol) vector. The G1 and G2 proteins specific ScFv genes were first expressed in E.coli and the function and binding properties were identified. The gene of ScFv were further inserted into intracellular expression vectyrs pEF/ myc/ ER and pEF/ myc/ CYTO vector and transfected Vero E6 cell. The clonal cell line which stabl expresses ScFv were isolated under the pressure of G418.

RESULTSThe ScFv genes of hantavirus G1 and G2 specific antibodies were successfully expressed in subcellular compartment ER and Cyto of Vero E6 cells and specifically targeted G1 and G2 protein after virus infection of the cells.

CONCLUSIONSThe recombination of intrabody to Hantann virus glycoprotein was constructed successfully, and it may provide basic material for the studying antiviral gene therapy and the molecular mechanism of viral replication and infection.

Animals ; Antibodies, Viral ; biosynthesis ; genetics ; immunology ; Cercopithecus aethiops ; Cloning, Molecular ; Endoplasmic Reticulum ; virology ; Glycoproteins ; biosynthesis ; genetics ; immunology ; Hantaan virus ; chemistry ; genetics ; immunology ; Humans ; Polymerase Chain Reaction ; Transfection ; Vero Cells ; Viral Envelope Proteins ; biosynthesis ; genetics ; immunology

The highly virulent PRRSV isolate strain HN-1/06 was cultivated on Marc-145. To study the viral entry mechanisms, the GP5 gene of PRRSV isolate was amplified by RT-PCR and cloned into pcDNA3.0 to generate the expressing plasmid pcDNA-GP5. pcDNA-GP5 was transfected into 293T by the calcium phosphate precipitation method. Analysis of flow cytometry confirmed that the GP5 proteins were expressed in surface of the 293T cells. Then 293T cells were transfected with pcDNA-GP5, pHIT60 and pHIT111 plasmids to generate pseudotyping virus. The pseudotyping virus supernatant was harvested 48 hours post-transfection and was detected by Western blotting and infection assay. Western blotting indicated that the GP5 glycoproteins were incorporated into the retroviral pseudotyped virus. Infection assay showed that the pseudotyped virus infected 293T and Mark-145 cell. The pseudotyped virus could be used to further study infectious mechanism of PRRSV.
Animals ; Cell Line ; Cloning, Molecular ; Endothelial Cells ; cytology ; metabolism ; virology ; Leukemia Virus, Murine ; genetics ; metabolism ; Mice ; Porcine respiratory and reproductive syndrome virus ; chemistry ; genetics ; Recombinant Proteins ; biosynthesis ; genetics ; Swine ; Transfection ; Viral Envelope Proteins ; biosynthesis ; genetics ; Virion ; genetics ; metabolism

OBJECTIVETo construct sub-unit vaccines of dengue virus type 1 to 4 and to analyze its immunogenicity.

METHODSEnvelope domain III s of dengue serotypes 1 and 2, as well as 3 and 4, were spliced by a linker (Gly-Gly-Ser-Gly-Ser)3 and cloned into vector pET-30a, then transformed into E. coli to express recombinant fusion proteins. The recombinant proteins were purified by high-performance liquid chromatography and mixed to immunize BALB/c mice. The neutralizing antibodies were tested by neutralizing assay, as well as in newborn mice challenged intracranially with dengue virus type 1 to 4.

RESULTSMice immunized with proteins could produce neutralizing antibodies, with titers of 1:34. 9, 1: 45.3, 1: 24.7 and 1:38.4 for DEN-1 to 4 respectively. 100% newborn mice challenged with DEN-1 or 2 in combination with sera from mice immunized with recombinant proteins were protected, whereas 83% protection was obtained when challenged with DEN-3 or 4.

CONCLUSIONThe recombinant proteins possess excellent immunogenicity to induce neutralizing antibodies and would be valuable for development of a tetravalent sub-unit vaccine.

Animals ; Antibodies, Neutralizing ; immunology ; Dengue Vaccines ; chemistry ; genetics ; immunology ; Dengue Virus ; genetics ; immunology ; Escherichia coli ; genetics ; metabolism ; Mice ; Mice, Inbred BALB C ; Neutralization Tests ; Recombinant Fusion Proteins ; genetics ; immunology ; Viral Envelope Proteins ; genetics ; immunology

Dengue virus (DENV) envelope [E] protein is the major surface protein of the virions that indued neutralizing antibodies. The domain III of envelope protein (EDIII) is an immunogenic region that holds potential for the development of vaccines; however, the epitopes of DENV EDIII, especially neutralizing B-cell linear epitopes, have not been comprehensively mapped. We mapped neutralizing B-cell linear epitopes on DENV-1 EDIII using 27 monoclonal antibodies against DENV-1 EDIII proteins from mice immunized with the DENV-1 EDIII. Epitope recognition analysis was performed using two set of sequential overlapping peptides (16m and 12m) that spanned the entire EDIII protein from DENV-1, respectively. This strategy identified a DENV-1 type- specific and a group-specific neutralizing epitope, which were highly conserved among isolates of DENV-1 and the four DENV serotypes and located at two regions from DENV-1 E, namely amino acid residues 309-320 and 381-392(aa 309-320 and 381-392), respectively. aa310 -319(310KEVAETQHGT319)was similar among the four DENV serotypes and contact residues on aa 309 -320 from E protein were defined and found that substitution of residues E309 , V312, A313 and V320 in DENV-2, -3, -4 isolates were antigenically silent. We also identified a DENV-1 type-specific strain-restricted neutralizing epitope, which was located at the region from DENV-1 E, namely amino acid residues 329-348 . These novel type- and group-specific B-cell epitopes of DENV EDIII may aid help us elucidate the dengue pathogenesis and accelerate vaccine design.
Amino Acid Sequence ; Animals ; Antibodies, Neutralizing ; immunology ; Dengue ; virology ; Dengue Virus ; chemistry ; genetics ; immunology ; Epitope Mapping ; Epitopes, B-Lymphocyte ; chemistry ; genetics ; immunology ; Humans ; Mice ; Molecular Sequence Data ; Viral Envelope Proteins ; chemistry ; genetics ; immunology