Detection of antibodies and nucleic acid of hepatitis E virus in pregnant women in Zhejiang Province / 中华传染病杂志

Objective To analyze the hepatitis E virus (HEV) infection status and the molecular characteristics of HEV isolated from pregnant women in Zhejiang Province.Methods Totally 98 236 serum samples collected from pregnant women during the year 2013 to 2015 were tested for HEV IgM by enzyme-linked immunosorbent assay (ELISA) and samples positive for IgM were detected for nucleic acid of HEV by nested polymerase chain reaction (PCR).The whole gene of HEV open reading frame 2 (ORF2) was further amplified and the prevalence was analyzed in nucleic acid-positive samples.Results Three hundred and fifty-two out of 98 236 serum samples were tested positive for HEV IgM,with positive rate of 0.36％.All the samples were simple positive of HEV IgM except for two samples co-infected with hepatitis B virus.HEV specific nucleic acid fragments were detected positive from three serum samples.Further phylogenetic analysis revealed that all the three HEV isolates in this study belonged to HEV genotype 4.Three isolates did not cluster in one branch,although they shared high nucleic acid homology and more than 97 ％ of amino acid homology.Variations were found significantly between sample sequence and other published HEV 4 isolates,including two variable regions found in the ORF2 gene (1-460 nucleotide and 620-870 nucleotide).However,the synonymous and non-synonymous substitutions rates in the two regions were similar,and neutral selection was the main evolutionary pressure.Conclusions HEV infection rate in pregnant women of Zhejiang Province is similar with the published data.The HEV isolates obtained in this study belong to genotype 4 with high variation rate.

Development of Enzyme-Linked Immunosorbent Assays Using 2 Truncated ORF2 Proteins for Detection of IgG Antibodies Against Hepatitis E Virus

BACKGROUND: Without appropriate culture systems for hepatitis E virus (HEV), sufficient natural viral proteins are difficult to generate for use in serological tests. Therefore, it is important to produce large amounts of HEV recombinant proteins in an economical way. The present study developed ELISAs using 2 truncated forms of the HEV open reading frame (ORF) 2 protein in order to detect anti-HEV IgG in serum samples. METHODS: Two truncated forms of the ORF2 protein were expressed in Escherichia coli and were purified by Ni2+-chelate-affinity chromatography (Qiagen, Germany). Two ELISAs were developed using these proteins and were compared with DIA.PRO HEV IgG ELISA kit (DIA.PRO. Italy) in 220 serum samples. RESULTS: High yields of the target proteins were obtained through codon optimization. The concentration and purity of the proteins were improved with Amicon filters (EMD Millipore, USA). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting analysis of the resultant proteins showed a protein band of approximately 60 kDa corresponding to ORF2.1 (amino acids 112-660) and a protein band of approximately 55 kDa corresponding to ORF2.2 (amino acids 112-607). Positive agreement, negative agreement, and concordance of the 2 in-house ELISAs compared with DIA.PRO HEV IgG ELISA kit were 87%, 99.5%, and 98.1%, respectively (kappa=0.899, P=0.625). CONCLUSIONS: The newly developed ELISAs are useful for detecting anti-HEV IgG in serum samples and are highly concordant with DIA.PRO HEV IgG ELISA kit.

SLC25A4 and C10ORF2 Mutations in Autosomal Dominant Progressive External Ophthalmoplegia

BACKGROUND AND PURPOSE: Progressive external ophthalmoplegia (PEO) with Mendelian inheritance is a heterogeneous group of diseases associated with multiple deletions of mitochondrial DNA (mtDNA), which results from the disturbed replication and maintenance of mtDNA secondary to the mutations of nuclear genes including POLG, SLC25A4, C10ORF2, POLG2, OPA1, and RRM2B. The aim of this study was to identify the genetic defects underlying the pathology and clinical features in two Korean kindreds with autosomal dominant PEO. METHODS: Two pathologically proven PEO patients with a clear autosomal dominant pattern of inheritance were selected. To exclude a large-scale rearrangement, a long-range polymerase chain reaction (PCR) was performed using DNA extracted from biopsied muscle tissue taken from each patient. All coding regions and exon-intron boundaries of POLG, SLC25A4, C10ORF2, and POLG2 were amplified by PCR and directly sequenced. RESULTS: One patient showed multiple deletions of mtDNA on long-range PCR analysis, and two known heterozygous missense mutations in SLC25A4 (p.Asp104Gly) and C10ORF2 (p.Glu479Lys) were identified in each patient. The p.Asp104Gly mutation in SLC25A4 was identified in the patient with an early onset, slowly progressive, pure PEO phenotype, while the p.Glu479Lys mutation in C10ORF2 was identified in the other patient, with a late-onset disease and PEO plus phenotype. CONCLUSIONS: Two mutations affecting nuclear genes were identified in Korean patients with autosomal dominant PEO. Further studies are necessary to identify the clear pathogenetic mechanisms and establish genotype-phenotype correlations in autosomal dominant PEO.

An ELISA Based on a Truncated Soluble ORF2 Protein for the Detection of PCV2 Antibodies in Domestic Pigs / 中国病毒学·英文版

Postweaning multisystemie wasting syndrome (PMWS) is an important swine disease that is closely associated with porcine circovirus type 2 (PCV2). The capsid protein (Cap protein) is a major structural protein that has at least three immunoreactive regions, and it can be a suitable candidate antigen for detecting the specific antibodies of a PCV2 infection. In the present study, an indirect enzyme-linked immunosorbent assay (TcELISA)based on a truncated soluble Cap protein produced in Escherichia coli (E.coli) was established and validated for the diagnostic PCV2 antibodies in swine. The TcELISA was validated by comparison with an indirect immunofluorescence assay (IIFA). The diagnostic sensitivity (DSN), specificity (DSP), and accuracy of the TcELISA were 88.6%, 90.7% and 89.4%, respectively. The agreement rate was 89.38% between results obtained with TcELISA and IIFA on 113 field sera. A cross-reactivity assay showed that the method was PCV2-specific by comparison with other sera of viral disease. Therefore ,the TcELISA will be helpful for the development of a reliable serology diagnostic test for large scale detection of PCV2 antibodies and for the evaluation of vaccine against PCV2 in swine.

Effects of L1-ORF2 fragments on green fluorescent protein gene expression

The retrotransposon known as long interspersed nuclear element-1 (L1) is 6 kb long, although most L1s in mammalian and other eukaryotic cells are truncated. L1 contains two open reading frames, ORF1 and ORF2, that code for an RNA-binding protein and a protein with endonuclease and reverse transcriptase activities, respectively. In this work, we examined the effects of full length L1-ORF2 and ORF2 fragments on green fluorescent protein gene (GFP) expression when inserted into the pEGFP-C1 vector downstream of GFP. All of the ORF2 fragments in sense orientation inhibited GFP expression more than when in antisense orientation, which suggests that small ORF2 fragments contribute to the distinct inhibitory effects of this ORF on gene expression. These results provide the first evidence that different 280-bp fragments have distinct effects on the termination of gene transcription, and that when inserted in the antisense direction, fragment 280-9 (the 3' end fragment of ORF2) induces premature termination of transcription that is consistent with the effect of ORF2.

Characterization of the homodimer and antigenicity of ORF2 polypeptides of genotype 4 hepatitis Evirus / 中华微生物学和免疫学杂志

Objective To characterize the dimerization and the antigenicity of the ORF2 polypep-tide of hepatitis E virus (HEV, genotype 4). Methods HEV ORF2 gene was cloned from the serum of a patient with hepatitis E. The genotype was determined by sequencing. Three ORF2 polypeptides differing in size and other polypeptides with point mutations were produced in E. coli. The recombinant polypeptides were purified and analyzed by SDS-PAGE and Western blot. Results The ORF2 polypeptide containing 459-607 amino acid formed homedimer even in 8 mol/L urea. The truncated polypeptides containing amino acid 472-607 or 459-594 formed monomer only. The mutations at amino acid 562 or 595 disrupted the ho-modimer, whereas the mutations at amino acid 476 or 580 did not. Anti-HEV from hepatitis E patients only reacted with the homodimer form of the polypeptide 459-607 and did not react with monomer or tnmcated pol-ypeptides. Conclusion The amino acid 459-607 of HEV ORF2 is essential for dimerization of the ORF2 polypeptide. Residues at amino acid 562 and 595 are critical for the dimerization. The antigenicity of the polypeptide 459-607 mainly depends on its homodimer form.

Expression of ORF_2 protein from hepatitis E virus in 293 cell / 临床检验杂志

Objective To study the immunoreaction of the recombinant proteins encoded by the fragments of ORF2 ( second open reading frames) gene of hepatitis E virus ( HEV). Methods The aimed sequence from the full-length ORF2 in clone PEH2 , which was derived from a Chinese strain of HEV,was amplified and cloned it into vector pcDNAS. 1 which was then transfected to 293 cell. Results The ORF2 protein was present in the soluble fractions of the cell lysate. The expressed protein of HEV ORF2 in 293 cells by using a plasmid pcDNA3. 1-based system showed positive on immunoblots probed against antibodies raised in BALB/c mice. Conclusion The experimental results laid a foundation for developing diagnostic reagent to detect HEV by using the expressed products of ORF2 protein.

Nucleotide Sequencing and Expression of Type 2 Porcine Circoviruses Isolated in Korea

Porcine circovirus (PCV) is a small, nonenveloped virus that contains a single-stranded circular DNA genome of about 1.76 Kb and belongs to the family Circoviridae. The PCV-2 was thought to be one of the causative agents for postweaning multisystemic wasting syndrome (PMWS) in pigs. In this study, the complete genome of two PCV-2 Korean isolates (KSY-1 and KSY-2) were sequenced and characterized. Also, the ORF2 gene of KSY-1 isolate was expressed in baculovirus expression system and the expressed protein was characterized. The sequence data indicated that the PCV-2 genome of two Korean isolates were 1,768 bases in length and encoded 2 major proteins, Rep (ORF1, 314 amino acids, 37 kDa) and a capsid (ORF2, 233 amino acids, 28~30 kDa) protein. There were 5 glycosylation sites and stem-loop structures with the nonanucleotide (5-AAGTATTAC-3), typically seen in PCV-2. Compared to nucleotide sequences of PCV-1 and PCV-2 reference strains, two Korean isolates were closely related; that is, they showed 98% homology in nucleotide sequence each other. Also, they showed 95~99% homology in nucleotide sequences with those of PCV-2 isolates but 76% similarity with those of PCV-1 reference strains. A phylogenetic analysis revealed that nucleotide sequences of Korean isolates were close to those of PCV-2 (AF055392) isolated in Canada. The baculovirusexpressed ORF2 migrated at 30 kDa and reacted with PCV-2 specific antiserum by indiect fluorescent antibody and Western blot analyses. It is concluded that our results could be valuable to understand the molecular characteristics of PCV-2 and to develop diagnostic methods for PCV-2 infections.