Study on key amino acids in E2 protein of recombinant side chain of dioxygate dehydrogenase complex in primary biliary cholangitis / 中华风湿病学杂志

Objective:To explore the key amino acids of side chain dioxate dehydrogenase complex E2 protein (BCOADC-E2) that can react specifically with specific autoantibody anti-mitochondrial antibodies (AMA)-M2 in patients with primary biliary cholangitis (PBC).Methods:The homologous target gene BCKD, which expressed the epitopes of BCOADC-E2 protein, was cloned and recombined with the engineering plasmid pGEX-4T1. Fifteen point mutant plasmids were obtained by polymerase chain reaction (PCR) and transferred to the prokaryotic expression strain for protein expression and purification. Fourteen mutant proteins and one wild-type protein were obtained. The AMA-M2 specificity of the 14 mutant proteins was measured by enzyme-linked immuno sorbent assay (ELISA), and the amino acids that were critical to the specificity of BCOADC-E2 and AMA-M2 were identified by comparing the specificity of the 14 mutant proteins with that of the wild type proteins. Differences between groups were analyzed by analysis of variance, LSD- t test. Results:A total of 14 mutant proteins and 1 wild-type protein were obtained.The specific reaction degree of mutant protein pGEX-BCKD-S1A (1.634±0.328) and pGEX-BCKD-C3A (1.744±0.345) with serum AMA-M2 in patients with PBC was higher than that of wild-type protein pGEX-BCKD (1.000±0.000) with AMA-M2; Mutant protein pGEX-BCKD-E4A (0.157±0.067), pGEX-BCKD-V5A (0.057±0.029), pGEX-BCKD-Q6A (0.580±0.166), pGEX-BCKD-S7A (0.744 ±0.125), pGEX-BCKD-D8A (0.351 ±0.135), pGEX-BCKD-S10A (0.496 ±0.158), pGEX-BCKD-V11A(0.149±0.089), pGEX-BCKD-T12A(0.061±0.043), pGEX-BCKD-I13A(0.007±0.017), pGEX-BCKD-T14A (0.198±0.101), pGEX-BCKD-S15A (0.156±0.087), The specific reaction degree of pGEX-BCKD-R16A (0.884±0.099) with AMA-M2 was lower than that of wild-type protein pGEX-BCKD (1.000±0.000) with AMA-M2.Conclusion:The cysteines at positions 1 and 3 of BCOADC-E2 protein were the key amino acids to improve the specific reaction between BCOADC-E2 and AMA-M2. The mutant proteins formed after amino acids at position 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15 and 16 are replaced by alanine can decrease the specificity of AMA-M2. Amino acids at positions 5 and 13 are the key amino acids that affect the specific reaction between BCOADC-E2 and AMA-M2, and have an important effect on the function of BCOADC-E2 protein.

First isolation and identification of Getah virus SC1210 in Sichuan / 中华实验和临床病毒学杂志

Objective@#To study the genome molecular characteristics of Getah virus (SC1210) which isolated in Sichuan province in 2012.@*Methods@#Reverse transcriptase polymerase chain reaction (RT-PCR) was used to identify the isolate and the genome was sequenced by the second Ion Torrent PGM. Computer softwares, including Mega Align and Mega 6, were used to analyze the nucleotide and deduced amino acid sequence, and draw phylogenetic trees.@*Results@#SC1210 was identified as Getah virus. The full genome sequence was 11 690nt, the nucleotide and amino acid homology of the full sequence with other strains were 99.2%-99.7% and 96.5%-99.4%.The capsid protein of SC1210 consisting of 804 nucleotides, encoding 268 amino acids and the full-length of E2 protein, had 1 266 nucleotides, encoding 422 amino acids. The nucleotide homology of the capsid protein and the E2 protein with other strains were 94.9%-99.2% and 94.6%-99.6%, and the amino acid were 97%-99.6% and 97.1%-99.5%. The 3′ UTR of the virus included 402 nucleotides and there were three repeat sequence elements and 19 nucleotides conservation sequence.@*Conclusions@#The first GETV isolate SC1210 in Sichuan province has a closer relationship with Yunnan strain YN040 and a far genetic relationship with MM2021.

Western Blot Detection of Human Anti-Chikungunya Virus Antibody with Recombinant Envelope 2 Protein

Chikungunya virus (CHIKV), a tropical pathogen, has re-emerged and has massive outbreaks abruptly all over the world. Containing many dominant epitopes, the envelope E2 protein of CHIKV has been explored for the vaccination or diagnosis. In the present study, the antigenicity of a recombinant expressed intrinsically disorder domain (IUD) of E2 was tested for the detection of the antibody against CHIKV through western blot method. The gene of the IUD of E2 was inserted into 2 different vectors and expressed as recombinant GST-E2 and recombinant MBP-E2 fusion protein, respectively. Two kinds of fusion proteins were tested with 30 CHIKV patient sera and 30 normal sera, respectively. Both proteins were detected by 25 patients sera (83.3%) and 1 normal serum (3.3%). This test showed a relatively high sensitivity and very high specificity of the recombinant E2 proteins to be used as diagnostic antigens against CHIKV infection.

Inflammatory response of endothelial cells to hepatitis C virus recombinant envelope glycoprotein 2 protein exposure

The hepatitis C virus (HCV) encodes approximately 10 different structural and non-structural proteins, including the envelope glycoprotein 2 (E2). HCV proteins, especially the envelope proteins, bind to cell receptors and can damage tissues. Endothelial inflammation is the most important determinant of fibrosis progression and, consequently, cirrhosis. The aim of this study was to evaluate and compare the inflammatory response of endothelial cells to two recombinant forms of the HCV E2 protein produced in different expression systems (Escherichia coli and Pichia pastoris). We observed the induction of cell death and the production of nitric oxide, hydrogen peroxide, interleukin-8 and vascular endothelial growth factor A in human umbilical vein endothelial cells (HUVECs) stimulated by the two recombinant E2 proteins. The E2-induced apoptosis of HUVECs was confirmed using the molecular marker PARP. The apoptosis rescue observed when the antioxidant N-acetylcysteine was used suggests that reactive oxygen species are involved in E2-induced apoptosis. We propose that these proteins are involved in the chronic inflammation caused by HCV.

Efecto de la proteína E2 del virus de hepatitis C sobre la activación de células NK / Effect of E2 protein of hepatitis C virus on the activation of NK cells

En estudios previos, se ha descrito un disminución de la activación y actividad citotóxica de las células NK en los pacientes infectados con hepatitis C; sin embargo, se desconoce el mecanismo por el cual éste fenómeno ocurre. En el presente reporte se estudió el efecto de la proteína E2 de la envoltura del virus o de la estimulación de su receptor con el anticuerpo anti-CD81 sobre la fosforilación de tirosinas, serinas, las enzimas: proteína quinasa C y fosfoinositol 3 quinasa, el factor de transcrición Nfkb y el intercambiador de nueclotidos VAV de células NK de controles normales estimulados con anti-CD16. Ambos, la proteína E2 y anti-CD81, combinado o por separado inducen una disminución de la fosforilación de tirosinas y serinas, así como una marcada disminución de la fosforilación de PKC, NFkB, PI3K y en menor grado VAV. Se concluye que la proteína E2 sola y en conjunto con anti-CD81 inducen señales inhibitorias responsables de la disminución en la activación de las células NK de pacientes infectados por el VHC y que éste fenómeno puede ser responsable de la cronicidad que se reporta en dicha enfermedad

The decrease in NK cell activation and cytotoxic activity in patients infected with hepatitis C virus has been described; however, the mechanism by whcih this phenomenon occurs is not known. In the present report, the effect of the E2 protein of the virus envelope or the stimulation of its receptor CD81 with the antibody anti-CD81 on the phosphorylation of tyrosines, serine, the enzymes protein kinase C, phosphoinositol kinase 3 (PI3K), the transcription factor NfkB and the nucleotide exchange protein VAV was assessed in NK cells from normal controls stimulated with anti-CD16. Both the protein E2 and anti-CD81 by themselves or combined, generated a decrease in tyrosine, serine, and a marked decrease in the phosphorylation of PKC, NfkB, PI3k and in less extent in VAV. It is concluded that the E2 protein alone and combined with anti-CD81 induce inhibitory signals responseible for the decrease in the activation of NK cells of infected HCV patients and it could be responsible for the chronicity observed in this disease

Sequencing of E2 and NS5A regions of HCV genotype 3a in Brazilian patients with chronic hepatitis

Hepatitis C virus (HCV) is a major cause of liver disease throughout the world. The NS5A and E2 proteins of HCV genotype 1 were reported to inhibit the double-stranded (ds) RNA-dependent protein kinase (PKR), which is involved in the cellular antiviral response induced by interferon (IFN). The response to IFN therapy is quite different between genotypes, with response rates among patients infected with types 2 and 3 that are two-three-fold higher than in patients infected with type 1. Interestingly, a significant percentage of HCV genotype 3-infected patients do not respond to treatment at all. The aim of this paper was to analyse the sequences of fragments of the E2 and NS5A regions from 33 outpatients infected with genotype 3a, including patients that have responded (SVR) or not responded (NR) to treatment. HCV RNA was extracted and amplified with specific primers for the NS5A and E2 regions and the PCR products were then sequenced. The sequences obtained covered amino acids (aa) 636-708 in E2 and in NS5A [including the IFN sensitivity determining region (ISDR), PKR-binding domain and extended V3 region)]. In the E2 and NS5A regions, we did observe aa changes among patients, but these changes were not statistically significant between the SVR and NR groups. In conclusion, our results suggest that the ISDR domain is not predictive of treatment success in patients infected with HCV genotype 3a.

Partial genome molecular characteristics of Getah virus newly isolated in China / 中华微生物学和免疫学杂志

Objective To study the genome molecular characteristics of Getah virus(DY0824)which isolated in Shandong province,2008 by molecular biology methods.Methods Reverse transcriptasepolymerase chain reaction(RT-PCR)was used to amplify the structural gene and 3'UTR fragments then the RT-PCR products were inserted into PGEM-T easy to be sequenced.Computer software was used to analyze the nucleotide and deduced amino acid sequence,and draw phylogenetic trees,including Clustal X1.83 and MegaAlign and Mega4.Results The capsid protein of DY0824 consists of 804 nucleotides,encoding 268 amino acids and the full-length of E2 protein is 1266 nucleotides,encoding 422 amino acids.The nucleotide homology of the capsid protein and the E2 protein with other strains were 95.4%-99.9%and 94.8%-99.5%,and the amino acid were 97.4%-100%and 97.6%-100%.The 3'UTR of the virus include 401 nucleotides and there are three repeat sequence elements.Conclusion Compared with the prototype virus,the Getah virus isolated in Shandong province had 7 amino acid differences in capsid protein genes and 10 amino acid differences in E protein genes.The 3'UTR region had multi-nucleotide changes.

Expression and functional analysis of CRT-E2-EGFP fusion protein in B16 cells / 细胞与分子免疫学杂志

AIM: To detect the expression of the Calreticulin and HPV E2 Fusion Protein in B16, and study the effects on proliferation and apoptosis of B16 cell lines in vivo. METHODS: To construct eukaryotic fluoresce expression vector pEGFP-CRT-E2, pEGFP-CRT and pEGFP-E2. Then the recombinant plasmids were transfected into B16 cells by Lipofectamine 2000. The expression of proteins was detected by Western blot. The location of different GFP fusion proteins in B16 was tested by inverted fluoresce microscope. Flow cytometry was applied to detect the effects of fusion proteins on the growing of B16 and then the apoptosis effects of B16 induced by different proteins were observed. RESULTS: The correctly constructed recombinant plasmid pEGFP-CRT-E2 and the expression of CRT-E2 gene could be detected in B16 cells. Apoptosis of B16 cells could be detected after the transient transfection. Meanwhile, the apoptosis rate of B16 cells transfected by pEGFP-CRT-E2 was much higher than that of control cells. And cell cycle G1/G0 arrest was also found (P < 0.01). CONCLUSION: The eukaryotic expression plasmid pEGFP-CRT-E2 is successfully constructed and it could correctly express the fusion protein in B16 cells. And the B16 cells transfected by plasmid pEGFP-CRT-E2 could induce apoptosis.

Definition of the peptide mimotope of cellular receptor for hepatitis C virus E2 protein using random peptide library

BACKGROUND: Hepatitis C virus(HCV), a family of Flaviviridae, has a host cell-derived envelope containing a positive-stranded RNA genome, and has been known as the maj or etiological agent for chronic hepatitis, hepatic cirrhosis, and hepatocellular carcinoma. There remains a need to dissect a molecular mechanism of pathogenesis for the development of therapeutic and effective preventive measure for HCV. Identification of cellular receptor is of central importance not only to understand the viral pathogenesis, but also to exploit strategies for prevention of HCV. This study was aimed at identifying peptide mimotopes inhibiting the binding of E2 protein of HCV to MOLT-4 cell . METHODS: In this study, phage peptide library displaying a random peptides consisting of 7 or 12 random peptides was employed in order to pan against E2 protein. Free HCV particles were separated from the immune complex forms by immunoprecipitation using anti-human IgG antibody, and used for HCV-capture ELISA. To identify the peptides inhibiting E2-binding to MOLT-4 cells, E2 protein was subj ect to bind to MOLT-4 cells under the competition with phage peptides. RESULTS: Several phage peptides were selected for their specific binding to E2 protein, which showed the conserved sequence of SHFWRAP from 3 different peptide sequences. They were also able to recognize the HCV particles in the sera of HCV patient s captured by monoclonal antibody against E2 protein. Two of them, showing peptide sequence of HLGPWMSHWFQR and WAPPLERSSLFY respectively, were revealed to inhibit the binding of E2 protein to MOLT-4 cell efficiently in dose dependent mode. However, few membrane-associated receptor candidates were seen using Fasta3 programe for homology search with these peptides. CONCLUSION: Phage peptides containing HLGPWMSHWFQR and WAPPLERSSLFY respectively, showed the inhibition of E2-binding to MOLT-4 cells. However, they did not reveal any homologues to cellular receptors from GenBank database. In further study, cellular receptor could be identified through the screening of cDNA library from MOLT-4 or hepatocytes using antibodies against these peptide mimotopes.

Prediction,synthesis and characteristics of B-cell epitopes of CSFV envelope glycoprotein E2 / 中国免疫学杂志

Objective:Study on characteristics of two synthesizd peptides based on CSFV E2 protein. Methods:B cell epitopes of CSFV E2 antigen were predicted using accessibility and flexibility schemes, associated with antigenicity , secondary structure and multiple sites prediction. Two antigen peptides (Pep1 and Pep2) have been designed and synthesized and their reactivety were detected with 8 McAbs and antiserum against mE2 protein, then the peptides were conjugated with BSA and immunized rabbits respectively. Results:Both Pep1 and Pep2 could react with antiserum and McAb A11, Pep2 could interact with McAbD5 and McAbD8. Only Pep1 BSA conjugate can stimulate high level and specific antibodies.Conclusion: The peptide1 has good antigenicity.