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Objective To study the nucleotide and amino acid sequences of norovirus G Ⅱ.4/Sydney 2012 variants,in China.Methods Twenty-two stool specimens,confirmed as G Ⅱ.4/Sydney 2012-positive were collected from Beijing in the winter of 2012-2013.RT-PCR was performed to target the complete capsid gene.G Ⅱ.4/Sydney 2012 strains from other regions in China were searched and obtained from the GenBank.Nucleotide and amino acid sequences of G Ⅱ.4/Sydney 2012 strains were analyzed,using the CLUSTAL X (Version 1.83)and followed by phylogenetic analysis using Mega version 5.1.Results The complete major capsid nucleotide sequences of thirty-eight G Ⅱ.4/Sydney 2012 strains from seven regions in China were obtained.The VP1 nucleotide and amino acid sequences diversity were 0.1％-3.3％ and 0-3.1％,respectively.Result from phylogenetic analysis demonstrated that the G Ⅱ.4/Sydney 2012 variant shared a common ancestor with both the dominant norovirus G Ⅱ.4 variants Apeldoom 2008 and the New Orleans 2009.G Ⅱ.4/Sydney 2012 variants appeared to have had two A/D/E site combinations at the amino acid level,TSRN-GTT-SNT and TSRN-STT-SNT.Conclusion G Ⅱ.4/Sydney 2012 variant had been circulating in many regions in China.There seemed a high nucleotide and amino acid identity among G Ⅱ.4/Sydney 2012 strains collected from China.G Ⅱ.4/Sydney 2012 variants showed different A/D/E site combination from other pandemic G Ⅱ.4 variants.
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Objective To investigate the effect of hepatitis B virus core protein (HBc) dimer interfaces amino acids mutation on nucleocapsid assembly and HBV DNA replication. Methods Based on HBc three dimension structure, four HBc dimer interfaces domain mutation plasmids, pHBc14-18M,pHBc120-135M,pHBc23-39M and pHBc122-139M were constructed in pcDNA3.1 vector by PCR site-directed mutagenesis, there was a flag-tag at the C-terminal of all mutants for easy detection. Wild type core protein plasmid 1-183flag was also constructed as a positive control. The 4 mutants were cotransfected HepG2 cells with pHBV1.2 core negative plasmid (pHBV1.2-core-) ,which contained 1.2 copies of HBV whole genome but the core protein would not express due to a stop codon. The capsid formation, HBV pregenome(pgRNA) and HBV DNA replication mediate were analyzed by native agarose gel electrophoresis and Western blot, Northern blot and Southern blot , respectively. The 4 mutants were also cotransfected HepG2 cells with HBV wild type plasmid pHBV1.2 and examined by Southern blot. Virions in the medium were determined by native agarose gel electrophoresis and Western blot. Results Cotransfecting HepG2 cells with pHBV1.2-core- plasmid, pHBc14-18M,pHBc120-135M and pHBc122-139M mutant groups formed nucleocapsid-like structure but pHBc23-39M could not, Northern and Southern blot displayed no signal in all mutants except 1-183flag conrol group. In pHBV1.2 cotransfection experiment, HBV DNA replication was blocked in pHBc14-18M, pHBc120-135M and pHBc122-139M mutant groups, sharply decreased in pHBc120-135M and pHBc122-139M groups, correspondingly virons production in medium were also inhibited. pHBc23-39M mutant exerted no influence on HBV replication. Conclusion pHBc23-39M mutant can neither form nucleocapsid-like structure nor interact with wild type HBc dimmer to interfere HBV replication.On the contrast, pHBc14-18M, pHBc120-135M and pHBc122-139M mutants can form nucleocapsid-like structure by themselves, but this structure does not support HBV DNA synthesis. Besides, they can effectively inhibit wild type HBV DNA replication by contacting with wild HBc dimmers resulting in nucleocapsid dysfunction.
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Objective To observe the effects of PTD-hepatitis B core antigen (HBcAg) induced murine bone marrow-derived dendritic cells (DCs) maturation on T lymphocyte proliferation in vitro.Methods Bone marrow derived DCs isolated from BALB/c mice were cultured with recombinant granu|ocyte-macrophage colony-stimulating factor (rGM-CSF) and recombinant interleutin-4 (rIL-4)for 5 days.Tumor necrosis factor (TNF)-a,HBcAg and PTD-HBcAg were added to induce DCs maturation.The distribution and localization of intracellular immunofluorescence were observed by confocal microscopy,and DCs phenotypes were analyzed by flow cytometry.The level of IL-12 p70 in the supernatant was detected by enzyme linked immunosorhent assay (ELISA).The proliferation of T lymphocytes was performed by using cell counting kit-8 (CCK-8).All data were analyzed using t test.Results DCs were cultured and identified successfully.Recombinant PTD-HBcAg could penetrate into DCs cytoplasm while recombinant HBcAg was detected on the surface of cells.DCs surface molecules,such as CD80,CD86 and major histocompability complex (MHC) II were upregulated by PTDHBcAg;IL-12 p70 levels induced by 50 mg/L and 100 mg/L recombinant PTD-HBcAg were (142.50±18.31) ng/L and (124.30±15.12) ng/L,respectively,which were significantly higher than those induced by recombinant HBcAg [(42.31±4.21 ) ng/L,t = 9.234 and 9.045,respectively,P＜0.05].The proliferation of T lymphocytes induced by PTD-HBcAg was much higher than that in HBcAg group or positive control TNF-a group.Conclusions PTD-HBcAg could penetrate membrane of DCs and promote the differentiation and maturation of DCs.PTD-HBcAg could up-regulate the expressions of costimulatory molecules on cell surface of DCs,and enhance the ability of DCs on stimulating T lymphocytes proliferation and IL-12 p70 production.