Zhen-Dong Zhao

Peking University Health Science Center, Peping, Beijing, China

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Publications (5)1.7 Total impact

  • Jin-Cun Zhao · Zhen-Dong Zhao · Wei Wang · Xiao-Ming Gao
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    ABSTRACT: The spike (S) glycoprotein is one of the major structure proteins of SARS-associated coronavirus (CoV). Fragment 450-650 (S450-650) of the S protein contains receptor-binding domain and neutralizing epitopes. In this study, S450-650 was expressed with a histidine tag in Escherichia coli BL21. Bacterial inclusion bodies containing the recombinant S450-650 were solubilized with 8 M urea and then applied onto a Ni-nitrilotriacetic acid column. On-column refolding and purification was performed. Reduced glutathione and oxidized glutathione were included in the refolding buffer. In the wash and elution buffers, glycerol and glucose were necessary additives to prevent protein aggregation during purification. This refolding and purification procedure allowed production of S450-650 at up to 500 microg/ml in soluble form, which maintained appropriate antigenicity and immunogenicity. It was able to induce strong IgG responses in BALB/c mice. In Western blot assays, the recombinant S450-650 was recognized by monoclonal Ab against the His-tag and also sera from a convalescent SARS patient. S450-650-based ELISA system was able to detect anti-SARS-CoV IgG Abs in patient sera.
    No preview · Article · Mar 2005 · Protein Expression and Purification
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    ABSTRACT: To compare the sensitivity and specificity of four kits for detection of anti-severe acute respiratory syndrome (SARS)-CoV IgG in sera of SARS patients. Anti-SARS-CoV IgG was detected in 99 serial sera from 18 SARS patients and in 123 negative reference sera, using two enzyme linked immunosorbent assays (EIA No. A and No. B) and two indirect immunofluorescence assays (Australian IFA and Euroimmun IFA). Anti-SARS-CoV IgG was not detected in sera collected from SARS patients at the first week after onset by any of the four kits, however, it was detectable in sera obtained at the second week of illness by EIA No. B, and two IFA, but not by EIA No. A, with the positive rates of 57.1% (4/7), 57.1% (4/7) and 42.9% (3/7), respectively. The anti-SARS-CoV IgG was first determined in sera on the 9th day by Euroimmun IFA, 12th day by EIA No. B, 13th day by Australian IFA, and 16th day by EIA No. A. The positive rates of antibody on the 3rd week after onset were 84.2% (16/19), 94.7% (18/19), 78.9% (15/19) and 52.6% (10/19) respectively. They were identical since the 4th week after the disease onset. Through detection of 123 negative reference sera, the specificity of EIA No. A and two IFA was 100%, with exception of 94.9% for EIA No. B. The sensitivity and specificity of the two IFAs were relatively higher than that of the two EIAs. The quality of the two homemade EIAs should be improved.
    No preview · Article · Jul 2004 · Zhonghua liu xing bing xue za zhi = Zhonghua liuxingbingxue zazhi
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    ABSTRACT: AIM: To study the affecting factors on the production of antibodies in SARS patients. METHODS: In a total of 104 clinically diagnosed SARS patients, the relations among IgG antibody titer, patients age, duration and the dosage of cortiscosteroids therapy were investigated. RESULTS: Eighty-three (79.8%) patients were positive for SARS-Cov antibody. The range of time for the occurrence of the antibody was 8 to 32 days; the percentage for the occurrence of the antibody in the periods of 0-7, 8-14, 22-28, 29-35, 36-42, 43-56 and 57-63 d were 0, 50% (21/42, 63.6%) 42/62, 73.3% (44/60), 88.1%(37/42), 81%(17/21), 92.6% (25/27) and 50% (2/4) respectively. The titer of antibody also increased from 0.14±0.05 in 0-7 d to 0.69±0.10 (43-56 d) and started to reduce after 8 wk. The positive percentage and titers of antibody grew when the dosage of cortiscosteroids was added. The positive percentage of antibody in severe patients and mild patients were 95.7% (22/23) and 75.3% (61/81) respectively, and the titers of antibody in the severe patients were higher than that of the mild patients (P >0.05) and the same change was also found between 19-14 age group and 46-52 age group. CONCLUSION: 79.8% of SARS patients are positive for SARS-Cov antibody. The positive percentage and the titer of antibody grow gradually while the duration prolongs, but declines after 8 wk. It is positively related to the clinical condition, but not affected by the dosage of cortiscosteroids and the age of the patient.
    Preview · Article · Mar 2004 · World Chinese Journal of Digestology
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    ABSTRACT: To study the pathologic characteristics and pathogenesis of circulating blood leucocytes infected by severe acute respiratory syndrome associated coronavirus (SARS CoV or SCV) in SARS patients. Blood samples of 22 SARS patients were studied, and 4 healthy blood samples were observed as negative controls. The white blood cells were collected from whole blood. The ultrastructural characteristics were observed by transmission electron microscopy. CD45RO antibody was used for pre-embedding immunoelectron microscopy. The SARS viral sequence was detected with real-time polymerase chain reaction (RT-PCR). Coronavirus-like particles were founded in the leukocytes in 6 of the 22 blood samples. Five of them gave positive results in the real-time PCR. The number of granulocytes was increased (P < 0.05) and that of lymphocytes was decreased (P < 0.05) respectively. Immunoelectron microscopy showed that CD45RO positive T lymphocyte decreased to 6% - 7%. Circulating lymphocytes had the highest percentage of infection. The morphologic characteristics of coronavirus-like particles were spherical or oval in shape, about 80 - 120 nm in diameter, with a dense round core and a clear halo around the core. A distinct membrane and club-shaped surface projections were seen in the periphery. The particles were located in the cytoplasm, the cisternae of endoplasmic reticulum, Golgi apparatus and vesicles. Virus entered cells by endocytosis or membrane fusion and was released through a budding process. Our data suggested that lymphocytes, particularly T cells, were probably the target cells of SARS CoV. The viruses may actively infected the immune cells during SARS CoV acute infection phase and the destruction of target cells may be one of the important reasons for the death of the circulating leukocytes in SARS.
    No preview · Article · Jan 2004 · Zhonghua yi xue za zhi
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    ABSTRACT: To primarily investigate the changing mode of anti-SARS coronavirus IgG antibody in clinically diagnosed SARS patients and the possibility of subclinical infection in physicians and nurses through close association with SARS patients. The plasma levels of anti-SARS coronavirus IgG antibody of 57 normal subjects, 127 physicians and nurses worked in SARS wards for one month and 73 SARS patients with different course of SARS were measured by enzyme linked immunosorbent assay. Plasma anti-SARS coronavirus IgG antibody was not detected in normal subjects and the clinical personnel. After 0-7 days, 8-10 days, 11-14 days, 15-20 days of onset of disease, the positive rates were 0.33%, 52%, 86% respectively, and the general positive rate was 61%. The specificity and sensitivity of ELISA to detect plasma anti-SARS IgG antibody were satisfactory. Cases with positive reaction could be diagnosed as patients already infected by the virus. The specific IgG antibody didn't emerge in some patients in the early stage of the disease, and the negative results didn't indicate that they were not infected. And follow-up investigation should be made in those patients. Unlike common epidemic infectious diseases, SARS probably hadn't the potentiality of subclinical infection.
    No preview · Article · Jun 2003 · Beijing da xue xue bao. Yi xue ban = Journal of Peking University. Health sciences