Preparation and preliminary application of monoclonal antibodies against Trichokirin-S1, a small ribosome-inactivating peptide from the seeds of Trichosanthes kirilowii.

Trichokirin-S1, a small ribosome-inactivating peptide recently purified from the seeds of Trichosanthes kirilowii, has potential clinical applications because of its small molecular mass. Two stable strains of hybridomas (1F11 and 2A5) that can secrete highly specific monoclonal antibodies (mAbs) against Trichokirin-S1 have been developed using the hybridoma technique. The isotypes of these two mAbs, 1F11 and 2A5, were determined to be IgG2a and IgG1, respectively.

Identification of the immunogenic domains in HBsAg preS1 region using overlapping preS1 fragment fusion proteins.

Aim: The incorporation of hepatitis B virus (HBV) preS1 region into epitope-based vaccines against HBV has been accepted widely, but the incorporate site and size of preS1 sequence is controversial. Therefore our purpose was to further investigate its immunogenic domains for the epitope-based hepatitis B vaccine design.

Methods: Eight GST fusion proteins containing overlapping preS1 fragments in preS1 (21-119) region were expressed in E.

Expression of overlapping PreS1 fragment recombinant proteins for the determination of immunogenic domains in HBsAg PreS1 region.

In this study, eight preS1 fragments overlapped in preS1 (21-119) region of HBV adr subtype, i.e. preS1 (21-47), preS1 (34-59), preS1 (48-70), preS1 (60-85), preS1 (71-94), preS1 (86-109), preS1 (95-119) and preS1 (21-119), were cloned by PCR, and expressed as GST fusion proteins.

Preparation and primary application of monoclonal antibodies against a novel ribosome-inactivating protein Moschatin from pumpkin seeds.

Plant ribosome-inactivating proteins (RIPs) have multiple biological functions, and have been widely used in the studies on biomedical and agronomic applications. Moschatin is a novel single-chain RIP recently purified from pumpkin seeds, and it has been successfully applied to construct the immunotoxin that can selectively kill the cultured human melanoma cells. Six stable strains of hybridomas (2H8, 4A8, 5B6, 6F8, 4H10 and 6C2) that can secrete high specific monoclonal antibodies against Moschatin have been successfully prepared using hybridoma technique.

Purification and characterization of Moschatin, a novel type I ribosome-inactivating protein from the mature seeds of pumpkin (Cucurbita moschata), and preparation of its immunotoxin against human melanoma cells.

A novel ribosome-inactivating protein designated Moschatin from the mature seeds of pumpkin (Cucurbita moschata) has been successively purified to homogeneity, using ammonium sulfate precipitation, CM-cellulose 52 column chromatography, Blue Sepharose CL-6B Affinity column chromatography and FPLC size-exclusion column chromatography. Moschatin is a type 1 RIP with a pI of 9.4 and molecular weight of approximately 29 kD.

[Purification and partial characterization of luffin P1, a peptide with translational inhibitory activity and trypsin inhibitory activity, from seeds of Luffa cylindrica].

A peptide, luffin P1, from seeds of Luffa cylindrica, was purified by ammonia sulfate precipitation, CM-52 ion exchange chromatography, Blue-gel affinity chromatography and FPLC Mono S ion exchange chromatography. Its molecular weight was 5226.5 as determined by MALDI-TOF-MS analysis.

[Purification and characterization of trichokirin-S1, a novel ribosome-inactivating peptide from seeds of Trichosanthes kirilowii].

A novel peptide from the seeds of Trichosanthes kirilowii, trichokirin-S1, was purified by extraction of protein body, ammonia sulfate precipitation, Blue-gel affinity chromatography, FPLC Mono S ion exchange chromatography and Superose12 gel filtration chromatography. Its molecular weight was determined to be 11,426 by MALDI-TOF MS analysis. Its reaction mechanism to inactive ribosome was the same as that of the ribosome-inactivating protein trichosanthin, a rRNA N-glycosidase.

Purification and characterization of Luffin P1, a ribosome-inactivating peptide from the seeds of Luffa cylindrica.

A peptide designated Luffin P1 was purified from the seeds of Luffa cylindrica. Its molecular mass was determined to be 5226.1 Da by MALDI-TOF MS analysis.

Isolation, Purification and Characterization of a Group of Novel Small Molecular Ribosome Inactivating Protein -- LuffinS from Seeds of Luffa cylindrica.

A group of novel RIPs--LuffinS(1), LuffinS(2), LuffinS(3) (MW about 8 kD) were purified by ammonia sulfate precipitation, CM-52 chromatography, HRLC size chromatography and Mono S FPLC. LuffinS(1), LuffinS(2) and LuffinS(3) have similar weight of about 8kD, and their N-terminal amino acid is Ala, Pro and Thr respectively. The N-terminal nine amino acid sequence of LuffinS(2) was determined as Pro-Arg-Arg-Gly-Gln-Glu-Ala-Phe-Asp.

Determination of the Binding Epitope for Anti-trichosanthin Monoclonal Antibody T(8)C(12).

Western blot result showed that T(8)C(12), an anti-trichosanthin (TCS) monoclonal antibody, could bind to a CNBr-cleaved TCS fragment with MW of 8 kD. The epitope was located in 1-72 of the N terminal of TCS as shown by amino acid analysis. A random 6-aa peptide library cloned in pIII of phage M13 was screened by T(8)C(12).

Construction of Trichosanthin Mutant R122G and Its Activity Study.

AGG, the codon of 122 Arg of trichosanthin (TCS) was mutated to GGG (Gly) by U-DNA site-directed mutagenesis. The mutant TCS was expressed and purified from the supernatant of host cells, its activities were assayed and compared with expressed wild-type TCS. The results showed that the R122G TCS was still active as a RNA N-glycosidase but its ability to inhibit protein synthesis was 160-fold less than that of wild-type TCS, its abortifacient ability on mid-term gestated mice reduced from 100% to 9.

Expression of Fusion Protein Containing Androgen Receptor Segment and Preparation of Polyclonal Antibodies to Androgen Receptor.

The cDNA segment (1105-2224) of the androgen receptor was cloned into the pGEX-3X expression vector and expressed in E. coli. The soluble fusion proteins GST-AR were used to immunize rabbits to obtain polyclonal antibodies to androgen receptors.

In vitro Inhibition of Human Melanoma Cells by Immunotoxin Luffin B-Ng76.

Luffin B, a plan single-chain ribosome inactivating protein, was purified from seeds of Luffa cylindrica by Blue Sepharose CL-6B affinity chromatography. An immunotoxin was constructed with luffin B and Ng76, a monoclonal antibody to human melanoma cell M(21). Luffin B-Ng76 showed 4 000-fold more cytotoxic to target melanoma cells than free luffin B.

Get effective polyclonal antisera in one month.

According to the traditional immunization procedure, after the first injection of the sample A (emulsion of aimed antigen and Freund's complete adjuvant) to immunize rabbit, successive injections of the sample B (emulsion of aimed antigen and Freund's incomplete adjuvant) were followed every 2-4 weeks. In general, high titer of the corresponding polyclonal antisera will be observed after 4-5 injections of sample B in 3-4 months. This report presents a simply modified procedure that was able to stimulate the antisera formation in one month and achieve enough avidity to satisfy either Western blot or immunohistochemistry analysis.

Expression and characterization of hepatitis C Virus E2 glycoprotein fused to hepatitis B virus preS1(21-47) fragment in CHO cells.

To stably express hepatitis C virus (HCV) E2 glycoprotein in CHO cells and facilitate the detection and purification of the expression products, the gene fragment encoding N-terminal 277 amino acids of this protein was fused to the fragment encoding hepatitis B virus (HBV) preS1(21-47) region and inserted into a secretion vector pSecTagB. CHO cells transfected with the recombinant plasmid carrying fusion gene were selected under growth pressure of Zeocin. Secreted fusion products and its cell-associated counterpart were detected by Western blot using E2 specific or preS1 specific antibodies.

Purification and Characterization of Recombinant Hepatitis B Virus Surface Antigen SS1 Expressed in Pichia pastoris.

The purification of recombinant hepatitis B surface antigen, SS1 protein, expressed in Pichia pastoris, and the investigation of its physiochemical characters and immunogenicity were described here. Employing McAb immunoaffinity chromatography, this protein was purified to purity of 95%. The results of ELISA and Western blotting showed good antigenicity of this purified SS1 protein.

Purification and Partial Characterization of S-trichokirin, A New Small Ribosome-inactivating Protein, from Seeds of Trichosanthes kirilowii.

A new small ribosome-inactivating protein named S-trichokirin from the seeds of Trichosanthes kirilowii was purified by ammonia sulfate precipitation, CM-52 ion exchange chromatography, Sephacryl S-100 gel filtration and FPLC Mono S ion exchange chromatography. S-trichokirin has molecular weight about 8 kD, as determined by 15% SDS-PAGE and 15% Tris-Tricine PAGE. It was proved to be a strong basic protein with pI about pH 9.

Preparation and Use of a Monoclonal Antibodyagainst Luffin b.

Luffin b is one of the most toxic single chain plant ribosome inactivating proteins. It has been successfully used to prepare an immunotoxin against human melanoma cells. Two strains of hybridomas (1E5 and 2E1) were screened out using cell fusion technique which steadily secreted monoclonal antibodies against luffin b.

Cloning and Expression of Luffin-b cDNA from the Seeds of Luffa cylindrica.

Luffin-b with Mr. 28 kD, isolated from the seeds of Luffa cylindrica,is one of the most toxic single chain plant ribosome inactivating proteins. The cDNA sequence of luffin-b was already reported by Kataoka in 1992.

Expression, Purification and Preliminary Clinical Use of Recombinant HBsAg GST-PreS1(21--47 aa) Fusion Proteins.

Expression plasmids pGEXSI and pGEXSII containing one copy and two orderly joined copies of PreS1(21--47 aa) DNA fragment, respectively, were constructed. GST-PreS1(21--47 aa) and GST-2xPreS1(21--47 aa) fusion proteins were highly expressed in E.Coli TG1, induced by IPTG.

Detection of anti-preS1 antibodies for recovery of hepatitis B patients by immunoassay.

Aim: To establish a convenient immunoassay method based on recombinant antigen preS1(21-119aa) to detect anti-preS1 antibodies and evaluate the clinical significance of antibodies in hepatitis B.

Methods: The expression plasmid pET-28a-preS1 was constructed, and a large quantity of preS1(21-119aa) fragment of the large HBsAg protein was obtained. The preS1 fragment purified by Ni(2+)-IDA affinity chromatography was used as coated antigen to establish the indirect ELISA based on streptavidin-biotin system for detection of the anti-preS1 antibodies in sera from HBV-infected patients.

Development of the diagnostic immunoassay to detect anti-PreS1(21-47aa) antibody--a marker suggesting the health improvement of hepatitis B patients.

Background: A new immunoassay has been developed for the detection of the anti-PreS1(21-47aa) antibody in sera of hepatitis B virus (HBV)-infected patients. Anti-PreS1(21-47aa) antibody involves virus neutralization and is a new marker for diagnosing acute and chronic B hepatitis.

Methods: The expression plasmids pGEXS I and pGEXS II, which expressed glutathione S-transferase (GST) fusion proteins containing a copy of PreS1(21-47aa) peptide and two orderly joined copies of PreS1(21-47aa) peptide, were constructed.

The Application of Monoclonal Antibodies to the Imunoaffinity Purification of Human Ferritin.

There was difference between the reactivities of anti-human ferritin monoclonal antibodies, 6D6 and A-hF-C with liver and heart ferritins. 6D6 reacts with liver and heart ferritin with similar intensity, while A-hF-C reacts preferentially with liver ferritin. Two affinity gels were made with 6D6 and A-hF-C respectively, and used to purify ferritins from crude extracts of human liver and heart ferritins.

Affinity Purification of Hepatitis B Virus Surface Antigen Containing PreS1 Region.

The large protein of hepatitis B virus surface antigen (LHBs) contained an attachment site of HBV to liver cells and the antibodies to preS1 were virus-neutralizing. Therefore, vaccines containing preS1 would be more protective. However, One of the key problems in the preparation of gene-expressed proteins was the purification of the products.