Z Chen

Universität zu Lübeck, Lübeck, Schleswig-Holstein, Germany

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Publications (7)7.31 Total impact

  • R H Dennin, J Wo, Z Chen, Ch Roos
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    ABSTRACT: The DNA from PBMCs of both hepatitis C virus (HCV)-positive patients and healthy HCV-negative human individuals tested thus far contains essential parts--up to 272/341 nucleotides--of the HCV 5'-non-coding region (5'-NCR). These findings bring up the question of the possible evolutionary background of these sequences. Therefore, using the same methodology, we looked for the same sequences in animals closely related to man, i.e., in nonhuman primates (two chimpanzees, one orang-utan, one Debrazza monkey, two New World monkey species and a prosimian). The DNA from PBMCs of the studied animals belonging to nonhuman primates contains essential parts--up to 272/341 nucleotides--of the HCV 5'-non-coding region (5'-NCR). A common sequence of 82 nucleotides is contained in the DNA of all the tested animals but only the chimpanzee's DNA harbors the same, longer sequence region of 272/341 nucleotides of the 5'-NCR found in human DNA. The results may provide a clue as to the possible origin of parts of the IRES containing sequence area of the HCV.
    Zeitschrift für Gastroenterologie 01/2001; 38(12):925-31. · 1.67 Impact Factor
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    ABSTRACT: To explore the possibility and the efficacy of immune responses in mice inoculated with recombinant plasmid pCD-HCV1 and to lay a foundation for HCV nucleic acid vaccine development in the future. The gene fragment coding C and E regions of HCV-II (type I b) was inserted into pCD-SR alpha 1 expression vector and formed pCD-HCV1 and then was injected into quadriceps muscles of Balb/c mouse. Serum anti-HCV level of mice was tested by ELISA (A value). Spleen cells proliferation responses to HCV antigens were detected by 3H-TdR incorporation (cpm). Balb/c mice immunized with recombinant plasmid pCD-HCV1 three or four times can generate specific antibody responses to HCV antigens and the antibody levels gradually ascend to the plateaus and did not have the trend of descending in 18 weeks detected. The serum antibodies in mice immunized by recombinant plasmid pCD-HCV1 were 100 percent positive when the serum were diluted 40 times and the positive rate of antibody still were 16.6 percent positive when the serum were diluted 320 times. Balb/c mice immunized with recombinant plasmid pCD-HCV1 (100 micrograms, 50 micrograms 10 micrograms/mouse three times respectively) can elicit antibody responses to HCV antigens and the antibody levels of three groups were 0.70 +/- 0.07, 0.33 +/- 0.04 and 0.11 +/- 0.09 respectively. Spleen cells of Blab/c mice injected with pCD-HCV1 three times were induced to produce proliferation responses to HCVc + e specific antigens. These results demonstrated that constructs expressioning HCV core and envelope proteins can generate anti-HCVc + e specific antibody responses and lymphoproliferation responses in mice, which suggested it to be possible to elicit immune responses to viral epitopes from HCV via DNA immunization with HCV-DNA recombinant and to warrant further investigation as a potential vaccine against HCV infections.
    Chinese medical journal 12/1999; 112(11):1036-9. · 1.02 Impact Factor
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    ABSTRACT: This study aimed to look for further HCV-specific sequences at the DNA level of healthy, HCV-negative individuals. Here, the sequence section from nt 57 to nt 328 within the 5'-NCR was assayed. Different combinations of primers were used in the nested PCR without a preceding reverse transcriptase step, resulting in fragments of the expected molecular weight size and also shorter and longer ones. It shows that the major part of the 5'-non-coding region (5'-NCR) of the hepatitis C virus genome is present in the DNA fraction from peripheral blood mononuclear cells (PBMCs) of healthy, anti-HCV-negative individuals tested. Furthermore we designed experiments to prove the specificity of these findings, by using restriction enzymes for digest assays of the target DNA before PCR (pre-PCR digest) and of the products after PCR (post-PCR digest). In conclusion, our study indicates that the main part of the internal ribosome entry site (IRES) structure of HCV at least is contained in the DNA of the individuals tested.
    Clinical Chemistry and Laboratory Medicine 07/1999; 37(6):623-30. · 2.96 Impact Factor
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    ABSTRACT: To inquire into the immune responses to expression protein in mice immunized with genetic vaccine of hepatitis C virus (HCV) and lay a foundation for HCV genetic vaccine development in future. The gene fragments coding C and most E regions of HCV-II type were inserted into pCD-SRalpha(1) of eukaryotic expression vector and formed genetic vaccine constructs of pCD-HCV(1) and then was injected into the quadriceps muscles of Balb/c mice. The serum anti-HCV level of mice was tested by ELISA and peripheral blood mononuclear cell (PBMC) proliferative responses to HCV antigens were detected by (3)H-TdR incorporation method (cpm). The serum antibody level reached to 0.71 +/- 0.08 - 0.77 +/- 0.06 (A value, the same below) after genetic vaccine pCD-HCV(1) (100 microg/mouse) were inoculated into the mice (n = 12) three or four times while blank vector pCD-SRalpha(1) could not induce the mice (n = 8) to generate antibody response in same way. After the antibody levels in mice (n = 8) immunized by pCD-HCV(1) had ascended to peak value (0.71), there was no trend of descending during the following 18 weeks of detection (0.68 +/- 0.06 - 0.75 +/- 0.07). Specific fragment of HCV cDNA identified by polymerase chain reaction (PCR) from DNA extracted from the muscles of the mice after pCD-HCV(1) had been inoculated three months. PBMC proliferative responses to HCV synthetic peptides CP(9) and gene recombinant antigens C, E(1) in the mice immunized with pCD-HCV(1) were detected and its stimulation indexes (SI) were 4.07 +/- 1.58, 3.88 +/- 0.70 and 3.69 +/- 1.13 respectively and there was a significant difference (P < 0.001) as compared with that of PBMC in mice immunized with pCD-SRalpha(1). These investigations demonstrated that genetic vaccine constructs made of HCV structural region can induce Balb/c mice to generate antibody and PBMC proliferative responses to HCV antigens via DNA immunization.
    Zhonghua nei ke za zhi [Chinese journal of internal medicine] 06/1999; 38(6):390-2.
  • R H Dennin, Z Chen, J Wo
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    ABSTRACT: The sequence 'GOR47-1' is a consistent part of human DNA; the expressed polypeptide of it 'GOR' is accepted to be an autoantigen, and the anti-GOR an autoantibody. However, GOR47-1 was originally isolated through a cDNA clone from blood of a chimpanzee. This animal belonged to a series of chimpanzees, in which human plasma of a patient with non-A, non-B hepatitis had been passaged. To date, nothing is known how it is that this 'sequence GOR47-1' without recognizable self-replicating properties and allocated to the human genome could be isolated from a chimpanzee plasma. The aim of this study was to detect by polymerase chain reaction GOR47-1 sequences in healthy, anti-HCV-negative humans, HCV-positive patients, chimpanzee, snake, and in maize and tobacco plants. The GOR47-1 sequence is present not only in human DNA but also with a high degree of homology in chimpanzee DNA. Essential parts of this sequence are also present in DNA of a snake and the two plants listed above. Our findings reveal that the GOR47-1 sequence isolated from a chimpanzee was probably of the chimpanzee origin. This fact has not yet been considered up until now, when discussing the role of GOR/anti-GOR in humans particularly suffering from chronic hepatitis C.
    Zeitschrift für Gastroenterologie 11/1998; 36(10):877-82. · 1.67 Impact Factor
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    R H Dennin, Z Chen
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    ABSTRACT: No convincing support has been provided so far for the existence of extrahepatic hepatitis C virus particles that should correspond to the sometimes extremely high concentration of 'HCV-RNA' in serum or plasma. If a naturally occurring HCV-specific DNA were to be found, a concept for at least some phenomena in terms of the pathophysiology of HCV should become conceivable. DNA was extracted from peripheral blood mononuclear cells of eleven healthy, anti-HCV-negative individuals, including five long term blood donors, and cells from different cell lines. DNA was subjected to nested polymerase chain reaction omitting a reverse transcriptase step with primers of the 5'NC as well as part of the core region of HCV. Direct polymerase chain reaction, i.e. without a reverse transcriptase step, revealed HCV-specific sequences in the DNA fraction of peripheral blood mononuclear cells of different origin: healthy anti-HCV negative individuals, furthermore in HeLa and MT2 cells. The fragments found were of expected length as well as of shorter and of longer than expected length with respect to the sequence of the HCV genome framed by the primers applied. The results derived from additional hybridization, restriction endonuclase analysis, and sequencing demonstrated HCV-specific sequences in the expected fragments with both a high degree of homology and deletions, respectively, substitutions, as compared to a prototype strain. However, the longer than expected fragments also contained sequences not specific for HCV.
    European journal of clinical chemistry and clinical biochemistry: journal of the Forum of European Clinical Chemistry Societies 01/1998; 35(12):899-905.
  • Y Liu, Z Chen, N He
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    ABSTRACT: To study inhibitory effect of antisense oligodeoxynucleotide (asODN) on HCV in vitro. The H9 cells transfected by pCD-HCV, a recombinant HCV containing total HCV structural gene, were treated with two 15-mers phosphorothioate (PS) ODNs complementary (PS-ASON) and homologous (PS-ODN) to HCV core genomic region, which were labeled with digoxin (DIG). Spot blot hybridization was carried out. Treated by the two ODNs, rPS-ODN (a 15-mers PS ODN of random sequence) or PS-ASON were modified with two liposomes (DOTAP and Lipofectin) and calcium phosphate precipitation respectively. With a half-ration, the variation of level of HCV mRNA and HCV antigen expression was observed by RT-PCR and dot ELISA. 3H-TdR adding test was done to observe PS-ASON cytotoxicity. PS-ODN and PS-ASON were detected in the H9 cells. The target gene was hybridized to PS-ASON and PS-ODN labeled with DIG. PS-ASON cut down level of HCV mRNA and HCV antigen expression obviously. However, PS-ODN and rPS-ODN did not influence the level of the both. The time-dependent and dose-dependent inhibition of PS-ASON was observed. In contrast to free PS-ASON, both of liposomal PS-ASON showed more highly effective inhibition, but calcium phosphate precipitation-PS-ASON complex did not. The results showed PS-ASON did not influence the H9 cells growth at 10 mumol/L. PS-ASON complementary to HCV core gene is asODN and exerts antisense-inhibitory effect on the level of HCV translation obviously, but not on the level of HCV replication and transcription.
    Zhonghua yi xue za zhi 09/1997; 77(8):567-70.