Biomedical subjects

Shengli Bi

Publications and source records attributed to Shengli Bi.

11 recordsLinked to original sources

PubMed2004

Proteomic fingerprints for potential application to early diagnosis of severe acute respiratory syndrome.

BACKGROUND: Definitive early-stage diagnosis of severe acute respiratory syndrome (SARS) is important despite the number of laboratory tests that have been developed to complement clinical features and epidemiologic data in case definition. Pathologic changes in response to viral infection might be reflected in proteomic patterns in sera of SARS patients. METHODS: We developed a mass spectrometric decision tree classification algorithm using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry. Serum samples were grouped into acute SARS (n = 74; <7 days after onset of fever) and non-SARS [n = 1067; fever and influenza A (n = 203), pneumonia (n = 176); lung cancer (n = 29); and healthy controls (n = 659)] cohorts. Diluted samples were applied to WCX-2 ProteinChip arrays (Ciphergen), and the bound proteins were assessed on a ProteinChip Reader (Model PBS II). Bioinformatic calculations were performed with Biomarker Wizard software 3.1.1 (Ciphergen). RESULTS: The discriminatory classifier with a panel of four biomarkers determined in the training set could precisely detect 36 of 37 (sensitivity, 97.3%) acute SARS and 987 of 993 (specificity, 99.4%) non-SARS samples. More importantly, this classifier accurately distinguished acute SARS from fever and influenza with 100% specificity (187 of 187). CONCLUSIONS: This method is suitable for preliminary assessment of SARS and could potentially serve as a useful tool for early diagnosis.

Adolescent↗

PubMed2003

The structural characterization and antigenicity of the S protein of SARS-CoV.

The corona-like spikes or peplomers on the surface of the virion under electronic microscope are the most striking features of coronaviruses. The S (spike) protein is the largest structural protein, with 1,255 amino acids, in the viral genome. Its structure can be divided into three regions: a long N-terminal region in the exterior, a characteristic transmembrane (TM) region, and a short C-terminus in the interior of a virion. We detected fifteen substitutions of nucleotides by comparisons with the seventeen published SARS-CoV genome sequences, eight (53.3%) of which are non-synonymous mutations leading to amino acid alternations with predicted physiochemical changes. The possible antigenic determinants of the S protein are predicted, and the result is confirmed by ELISA (enzyme-linked immunosorbent assay) with synthesized peptides. Another profound finding is that three disulfide bonds are defined at the C-terminus with the N-terminus of the E (envelope) protein, based on the typical sequence and positions, thus establishing the structural connection with these two important structural proteins, if confirmed. Phylogenetic analysis reveals several conserved regions that might be potent drug targets.

Amino Acid Sequence↗

PubMed2003

The E protein is a multifunctional membrane protein of SARS-CoV.

The E (envelope) protein is the smallest structural protein in all coronaviruses and is the only viral structural protein in which no variation has been detected. We conducted genome sequencing and phylogenetic analyses of SARS-CoV. Based on genome sequencing, we predicted the E protein is a transmembrane (TM) protein characterized by a TM region with strong hydrophobicity and alpha-helix conformation. We identified a segment (NH2-_L-Cys-A-Y-Cys-Cys-N_-COOH) in the carboxyl-terminal region of the E protein that appears to form three disulfide bonds with another segment of corresponding cysteines in the carboxyl-terminus of the S (spike) protein. These bonds point to a possible structural association between the E and S proteins. Our phylogenetic analyses of the E protein sequences in all published coronaviruses place SARS-CoV in an independent group in Coronaviridae and suggest a non-human animal origin.

Amino Acid Sequence↗

PubMed2003

The structure analysis and antigenicity study of the N protein of SARS-CoV.

The Coronaviridae family is characterized by a nucleocapsid that is composed of the genome RNA molecule in combination with the nucleoprotein (N protein) within a virion. The most striking physiochemical feature of the N protein of SARS-CoV is that it is a typical basic protein with a high predicted pI and high hydrophilicity, which is consistent with its function of binding to the ribophosphate backbone of the RNA molecule. The predicted high extent of phosphorylation of the N protein on multiple candidate phosphorylation sites demonstrates that it would be related to important functions, such as RNA-binding and localization to the nucleolus of host cells. Subsequent study shows that there is an SR-rich region in the N protein and this region might be involved in the protein-protein interaction. The abundant antigenic sites predicted in the N protein, as well as experimental evidence with synthesized polypeptides, indicate that the N protein is one of the major antigens of the SARS-CoV. Compared with other viral structural proteins, the low variation rate of the N protein with regards to its size suggests its importance to the survival of the virus.

Amino Acid Motifs↗

PubMed2003

The R protein of SARS-CoV: analyses of structure and function based on four complete genome sequences of isolates BJ01-BJ04.

The R (replicase) protein is the uniquely defined non-structural protein (NSP) responsible for RNA replication, mutation rate or fidelity, regulation of transcription in coronaviruses and many other ssRNA viruses. Based on our complete genome sequences of four isolates (BJ01-BJ04) of SARS-CoV from Beijing, China, we analyzed the structure and predicted functions of the R protein in comparison with 13 other isolates of SARS-CoV and 6 other coronaviruses. The entire ORF (open-reading frame) encodes for two major enzyme activities, RNA-dependent RNA polymerase (RdRp) and proteinase activities. The R polyprotein undergoes a complex proteolytic process to produce 15 function-related peptides. A hydrophobic domain (HOD) and a hydrophilic domain (HID) are newly identified within NSP1. The substitution rate of the R protein is close to the average of the SARS-CoV genome. The functional domains in all NSPs of the R protein give different phylogenetic results that suggest their different mutation rate under selective pressure. Eleven highly conserved regions in RdRp and twelve cleavage sites by 3CLP (chymotrypsin-like protein) have been identified as potential drug targets. Findings suggest that it is possible to obtain information about the phylogeny of SARS-CoV, as well as potential tools for drug design, genotyping and diagnostics of SARS.

Amino Acid Sequence↗

PubMed2003

Complete genome sequences of the SARS-CoV: the BJ Group (Isolates BJ01-BJ04).

Beijing has been one of the epicenters attacked most severely by the SARS-CoV (severe acute respiratory syndrome-associated coronavirus) since the first patient was diagnosed in one of the city's hospitals. We now report complete genome sequences of the BJ Group, including four isolates (Isolates BJ01, BJ02, BJ03, and BJ04) of the SARS-CoV. It is remarkable that all members of the BJ Group share a common haplotype, consisting of seven loci that differentiate the group from other isolates published to date. Among 42 substitutions uniquely identified from the BJ group, 32 are non-synonymous changes at the amino acid level. Rooted phylogenetic trees, proposed on the basis of haplotypes and other sequence variations of SARS-CoV isolates from Canada, USA, Singapore, and China, gave rise to different paradigms but positioned the BJ Group, together with the newly discovered GD01 (GD-Ins29) in the same clade, followed by the H-U Group (from Hong Kong to USA) and the H-T Group (from Hong Kong to Toronto), leaving the SP Group (Singapore) more distant. This result appears to suggest a possible transmission path from Guangdong to Beijing/Hong Kong, then to other countries and regions.

Genome, Viral↗

PubMed2002

[Expression of thermal stable, soluble hepatitis E virus recombinant antigen].

BACKGROUND: To obtain thermal stable, soluble, biologically active hepatitis E virus recombinant antigen using thioredoxin fusion expression system. METHODS: HEV ORF2 gene fragment (6964-7126 nt) was inserted into thioredoxin fusion expression vector pThioHisA. The recombinant plasmid was transformed into E. coli BL21 strain. After induction with IPTG, cells were lysed and the supernatant was subjected to 80 degree treatment for 10 minutes. After centrifugation, the supernatant was tested by ELISA. RESULTS: SDS-PAGE analysis showed the thioredoxin. HEV fusion protein was highly expressed and was thermally stable, soluble. HEV specific ELISA confirmed this fusion protein possessing HEV specific antigenicity. CONCLUSIONS: Using thioredoxin fusion expression system, a soluble, thermal stable, biologically active HEV recombinant antigen was successfully expressed.

Antigens, Viral↗

PubMed2002

[Immunogenicity of recombinant HEV ORF2 protein expressed in pichia pastoris].

BACKGROUND: To study to immunogenicity of recombinant HEV ORF2 protein expressed in pichia pastoris. METHODS: BALB/c mice were immunized with the recombinant HEV ORF2 protein. The ability of antiserum to bind HEV was tested using affinity-capture reverse transcription polymerase chain reaction (RT-PCR). Moreover, the recombinant protein was used to immunize BALB/c mice by different routes with different adjuvants. Serum conversion rate of anti-HEV antibody and the ELISA titer were detected. RESULTS: The antiserum could capture native HEV for RT-PCR. As to the immunization effect, the immune response by intramuscular route was better than that of the intraperitoneal route. The protein with alum and CpG adjuvant could elicits more significant immune responses than using the alum adjuvant alone. The best way was to immunize with the protein with alum and CpG adjuvant by intramuscular route with a boosted injection on the 4th week after the first immunization. The ED50 was 0.023 microgram. This is the first report that the antibody elicited by recombinant HEV ORF2 protein expressed in pichia pastoris recognizes native HEV. High immunogenicity of this kind of ORF2 was also demonstrated by inducing strong immune response in mice with good ED50 result. CONCLUSIONS: The high immunogenicity of this kind of HEV ORF2 may make a foundation for the development of new type of hepatitis E vaccine.

Animals↗

PubMed2002

[Cloning and expression of simplex herpes virus ? US4 fragment].

BACKGROUND: To get early laboratory study of type specific antigenicity of herpes simplex virus II. METHODS: PCR and prokaryotic expression technique. RESULTS: Herpes simplex virus II type specific gene fragment was expressed in E.coli and the products can be used as specific antigen for the detection of anti\HSV in the recovery sera. CONCLUSIONS: Cloning and express of HSVII type specific antigen found the basis for developing specific diagnosis methods and vaccine of HSV.

Antigens, Viral↗

PubMed2002

[Expression of full-length hepatitis E virus structural gene using baculovirus expression system].

OBJECTIVE: To obtain recombinant baculovirus containing full-length structural gene of HEV and to express HEV structural protein. METHODS: Full-length structural gene of HEV (5147-7126 nt) was inserted into baculovirus expression vector pAcUW51. The recombinant plasmid and Baculo Gold DNA were co-transfected into insect cell line Sf9. Single plaque was picked and amplified and expression of HEV structural protein was tested by SDS-PAGE, Western blot and immunofluorescence methods. RESULTS: SDS-PAGE analysis showed HEV structural protein was highly expressed; Western blot and immunofluorescence assay showed that the expression product could specifically react with HEV positive sera, confirming the protein possessing HEV specific antigenicity. CONCLUSIONS: HEV structural protein was successfully expressed using baculovirus expression system.

Animals↗

PubMed2002

[Expression of the 3a and 3d fusion protein of hepatitis A virus in prokaryotic cell and antigenicity analysis].

OBJECTIVE: To fusionaly express the HAV 3a (located in 1403-1456 aa) and 3d located in 1719-1764 aa cDNA gene fragments in prokaryotic system; to investigate the antigenicity and application of recombinant protein. METHODS: By using PCR technique, 3a and 3d gene fragments were cloned. Choosing pET-30a as the expressive vector, the recombinant plasmid Pet-3ad was constructed and pET-3ad was expressed in Escherichia coli after inducing by IPTG. By affinity chromatography, purified recombinant protein was obtained. By using Western blot analysis and indirect ELISA to detect its antigenic activity. RESULTS: Recombinant plasmid pET-3ad was proved to construct successfully by enzyme-digestion and sequence measurement. Recombinant protein P3ad(18,000) was obtained in BL21(DE3) and purified after Ni+ affinity chromatography. Western blot analysis and indirect ELISA showed that P3ad had specific antigenicity. CONCLUSIONS: Recombinant plasmid pET-3ad was proved to construct successfully by enzyme-digestion (Nco I/Hind III) and sequence measurement. Recombinant protein P3ad(18,000) was obtained in BL21(DE3) and purified after Ni+ affinity chromatography. Specific immunoblotting appeared at 18,000 by western blot analysis, which showed the recombinant protein P3ad had specific antigenicity, indirect ELISA further proved its antigenicity.

Blotting, Western↗