X5 protein is one of the putative unknown proteins of SARS-CoV. The recombinant protein has been successfully expressed in E. coli in the form of insoluble inclusion body. The inclusion body was dissolved in high concentration of urea. Affinity Chromatography was preformed to purify the denatured protein, and then the product was refolded in a series of gradient solutions of urea. The purified protein was obtained with the purity of > 95% and the yield of 93.3 mg x L(-1). Polyclonal antibody of this protein was obtained, and Western blotting assay indicated that the X5 protein has the strong property of antigen. Sixty-eight percent of the recombinant protein sequence was confirmed by LC-ESI-MS/MS analysis.
Amino Acid Sequence ; Animals ; Antibodies ; isolation & purification ; Escherichia coli ; genetics ; metabolism ; Gene Expression Regulation, Viral ; Inclusion Bodies ; chemistry ; metabolism ; Molecular Sequence Data ; Rabbits ; Recombinant Proteins ; genetics ; immunology ; isolation & purification ; SARS Virus ; genetics ; Viral Proteins ; genetics ; immunology ; isolation & purification

Prokaryotic expression plasmids carrying N-terminal(1-163aa) and C-terminal(141-306aa) gene of HCoV-NL63 nucleocapsid protein were constructed with pET-30a(+) vector. Consequently, we prepared two purified proteins, Np and Cp, respectively, and established a Western blotting-based line assay (WBLA) for detection of antibodies against HCoV-NL63 using three purified proteins: Np , Cp and Nf, a full-length HCoV-NL63 nucleocapsid protein as previously reported. We detected anti-HCoV-NL63 antibodies among 50 sera samples collected from adult for health-examination by WBLA. The results showed that: 25 (50%), 27 (54%), 36 (72%) of 50 sera were indentified as anti-HCoV-NL63 antibody positive when the antigen was from Nf, Np and Cp, respectively. Among these sera with positive anti-HCoV-NL63 antibody,Cp showed highest antibody positive rate in WBLA,and consistent rates of detection were 64% between Nf and Np, 54% between Nf and Cp, 54% between Np and Cp. Our study provides the foundation for development of HCoV-NL63 serological detection reagents and an experimental tool for immunological research of HCoV-NL63 infection.
Adult ; Antibodies, Viral ; blood ; Blotting, Western ; Coronavirus ; chemistry ; immunology ; Humans ; Nucleocapsid Proteins ; genetics ; immunology ; isolation & purification ; Peptide Fragments ; genetics ; isolation & purification ; Recombinant Proteins ; biosynthesis ; immunology ; isolation & purification ; Serologic Tests

Dirofilaria immitis (heartworm) infections affect domestic dogs, cats, and various wild mammals with increasing incidence in temperate and tropical areas. More sensitive antibody detection methodologies are required to diagnose asymptomatic dirofilariasis with low worm burdens. Applying current transcriptomic technologies would be useful to discover potential diagnostic markers for D. immitis infection. A filarial homologue of the mammalian translationally controlled tumor protein (TCTP) was initially identified by screening the assembled transcriptome of D. immitis (DiTCTP). A BLAST analysis suggested that the DiTCTP gene shared the highest similarity with TCTP from Loa loa at protein level (97%). A histidine-tagged recombinant DiTCTP protein (rDiTCTP) of 40 kDa expressed in Escherichia coli BL21 (DE3) showed immunoreactivity with serum from a dog experimentally infected with heartworms. Localization studies illustrated the ubiquitous presence of rDiTCTP protein in the lateral hypodermal chords, dorsal hypodermal chord, muscle, intestine, and uterus in female adult worms. Further studies on D. immitis-derived TCTP are warranted to assess whether this filarial protein could be used for a diagnostic purpose.
Animal Structures/chemistry ; Animals ; Antibodies, Helminth/blood ; Antigens, Helminth/chemistry/*genetics/immunology/*isolation & purification ; Cloning, Molecular ; Dirofilaria immitis/chemistry/*genetics/immunology ; Disease Models, Animal ; Dogs ; Escherichia coli/genetics ; Gene Expression ; Molecular Sequence Data ; Molecular Weight ; Recombinant Fusion Proteins/chemistry/genetics/immunology/isolation & purification ; Sequence Analysis, DNA ; Tumor Markers, Biological/chemistry/*genetics/immunology/*isolation & purification

The nucleocapsid protein (N protein) has been found to be an antigenic protein in a number of coronaviruses. Whether the N protein in severe acute respiratory syndrome-associated coronavirus (SARS-CoV) is antigenic remains to be elucidated. Using Western blot and Enzyme-linked Immunosorbent Assay (ELISA), the recombinant N proteins and the synthesized peptides derived from the N protein were screened in sera from SARS patients. All patient sera in this study displayed strong positive immunoreactivities against the recombinant N proteins, whereas normal sera gave negative immunoresponses to these proteins, indicating that the N protein of SARS-CoV is an antigenic protein. Furthermore, the epitope sites in the N protein were determined by competition experiments, in which the recombinant proteins or the synthesized peptides competed against the SARS-CoV proteins to bind to the antibodies raised in SARS sera. One epitope site located at the C-terminus was confirmed as the most antigenic region in this protein. A detailed screening of peptide with ELISA demonstrated that the amino sequence from Codons 371 to 407 was the epitope site at the C-terminus of the N protein. Understanding of the epitope sites could be very significant for developing an effective diagnostic approach to SARS.
Blotting, Western ; Enzyme-Linked Immunosorbent Assay ; Epitopes ; chemistry ; immunology ; Humans ; Nucleocapsid Proteins ; chemistry ; immunology ; Peptide Fragments ; chemical synthesis ; Plasmids ; Recombinant Proteins ; immunology ; isolation & purification ; metabolism ; SARS Virus ; genetics ; immunology ; metabolism

Subolesin (4D8), the ortholog of insect akirins, is a highly conserved protective antigen and thus has the potential for development of a broad-spectrum vaccine against ticks and mosquitoes. To date, no protective antigens have been characterized nor tested as candidate vaccines against Dermacentor silvarum bites and transmission of associated pathogens. In this study, we cloned the open reading frame (ORF) of D. silvarum 4D8 cDNA (Ds4D8), which consisted of 498 bp encoding 165 amino acid residues. The results of sequence alignments and phylogenetic analysis demonstrated that D. silvarum 4D8 (Ds4D8) is highly conserved showing more than 81% identity of amino acid sequences with those of other hard ticks. Additionally, Ds4D8 containing restriction sites was ligated into the pET-32(a+) expression vector and the recombinant plasmid was transformed into Escherichia coli rosetta. The recombinant Ds4D8 (rDs4D8) was induced by isopropyl beta-D-thiogalactopyranoside (IPTG) and purified using Ni affinity chromatography. The SDS-PAGE results showed that the molecular weight of rDs4D8 was 40 kDa, which was consistent with the expected molecular mass considering 22 kDa histidine-tagged thioredoxin (TRX) protein from the expression vector. Western blot results showed that rabbit anti-D. silvarum serum recognized the expressed rDs4D8, suggesting an immune response against rDs4D8. These results provided the basis for developing a candidate vaccine against D. silvarum ticks and transmission of associated pathogens.
Animals ; Antigens/chemistry/genetics/*immunology/isolation & purification ; Arthropod Proteins/chemistry/genetics/*immunology/isolation & purification ; Chromatography, Affinity ; Cloning, Molecular ; Cluster Analysis ; Conserved Sequence ; Dermacentor/*genetics ; Electrophoresis, Polyacrylamide Gel ; Escherichia coli/genetics ; Gene Expression ; Humans ; Molecular Sequence Data ; Molecular Weight ; Phylogeny ; Recombinant Proteins/chemistry/genetics/immunology/isolation & purification ; Sequence Analysis, DNA ; Sequence Homology, Amino Acid

Human cytomegalovirus (HCMV) infection is an ubiquitous herpesvirus disease in human populations. It is rarely pathogenic to healthy adults, yet it may cause severe outcome to organ transplant recipients, the immunocompromised individuals and pregnant women. Using DNA from HCMV AD169 strain as template, the UL32 gene encoding pp150 protein fragment and the UL57 gene encoding MDBP protein fragment were amplified by PCR technique. After the construction of cloning vector pMD18-T-UL32, pMD18-T-UL57, pMD18-T-UL32/UL57 and expression vector pET-11a-UL32/UL57, the recombinant fusion proteins pp150/MDBP were induced with IPTG in BL21 host strain. The results showed that the relative molecular weight of recombinant fusion proteins pp150/MDBP is about 27 kD, the product of fusion proteins takes 17.45% in the total proteins in host bacteria, the analytical result was positive to the fusion proteins pp150/MDBP via Western blot technique, while the purified recombinant fusion proteins have strong antigenicity detected by ELISA and protein chip compared with whole virus antigens from HCMV. It was demonstrated that when used for the detection of serum from the clinical patients it has the same detection rate compared with the whole virus antigen. It needs further research for application.
Cytomegalovirus ; DNA-Binding Proteins ; chemistry ; Electrophoresis, Polyacrylamide Gel ; Enzyme-Linked Immunosorbent Assay ; Gene Expression ; Genetic Vectors ; genetics ; Humans ; Peptide Fragments ; blood ; genetics ; immunology ; isolation & purification ; Phosphoproteins ; chemistry ; Plasmids ; genetics ; Polymerase Chain Reaction ; Recombinant Fusion Proteins ; blood ; genetics ; immunology ; isolation & purification ; Transcription Factors ; chemistry ; Viral Matrix Proteins ; chemistry

To develop a sensitive and specific ELISA for detection of antibodies to the nonstructural protein of FMDV. We cloned and expressed FMDV nonstructural protein 3AB in Escherichia coli expression system. The recombinant protein 3AB was purified with Ni-NTA HisBind Resins and characterized by Western blotting. An indirect ELISA based on purified protein 3AB as a coating antigen was established. The specificity and sensitivity of this assay were evaluated by comparison with a commercial 3ABC-ELISA kit in detecion of serum samples. The results showed that the recombinant protein 3AB was expressed as a formation of inclusion bodies in Escherichia coli. The purified protein could specificially react with FMDV infection antibodies in Western blotting assay, but no reaction with the immune antibodies induced with vaccine. Two assays were no significant differences in specificity and sensitivity for detection of field samples (P>0.05). Therefore, we speculated that the recombinant protein 3AB is a promising molecular marker, which may effectively differentiate FMD-infected from vaccinated animals in a herd.
Animals ; Antibodies, Viral ; analysis ; Antigens, Viral ; biosynthesis ; genetics ; immunology ; Cattle ; Cattle Diseases ; diagnosis ; immunology ; Enzyme-Linked Immunosorbent Assay ; Escherichia coli ; genetics ; metabolism ; Foot-and-Mouth Disease ; diagnosis ; immunology ; Foot-and-Mouth Disease Virus ; chemistry ; genetics ; isolation & purification ; Genetic Vectors ; genetics ; Recombinant Proteins ; biosynthesis ; genetics ; immunology ; Viral Nonstructural Proteins ; biosynthesis ; genetics ; immunology

The use of tumor antigen specific antibody for the delivery of therapeutic agents offers the possibility of targeting therapy with reduced toxicity to normal tissues compared to conventional treatments. In previous work, the human-mouse chimeric antibody fragment Fab' directed against CD20 was constructed from the new anti-CD20 antibody HI47 (a mouse IgG3, K). The chimeric antibody fragment Fab' could reduce its antigenicity, but the yield, quality and affinity of chimeric antibody fragment Fab' restrict its use. To improve affinity of chimeric antibody fragment Fab', a new phasmid pYZcpp3, which expresses chimeric antibody fragment F(ab')2, was constructed by adding a sequence encoding a small peptide, (CPP)3, to C-terminus of heavy chain constant region of chimeric antibody fragment Fab'. Using the pYZcpp3 to transform E. coli. 16c9, the genetically engineered bacteria 10916# was obtained. 10916# can secret the soluble chimeric antibody fragment Fab' and F(ab')2 into periplasmic. The yield was up to 360 mg/L with the percent of F(ab')2 up to 45% in 19L fermentor by the high density fermentation technology. Without denaturation and renaturation, the F(ab')2 has possessed the native three-dimensional structure. The purity of F(ab')2 was more than 90% after the purification of protein G affinity chromatography and S200 size exclusion chromatography. The F(ab')2 could distinguish and bind to Raji cells (CD20+) by FACS. F(ab')2 could inhibit the proliferation of Raji cells in vitro by MTT, IC50 was 22.8 microg/mL. HI47 and its chimeric fragments F(ab')2 induced a significant level of apoptosis (23.5%, 20.8%, respectively), independent of any cross-linking agents, in Raji cells after 24 h incubation. The chimeric antibody fragment F(ab')2 directed against CD20 is possible to apply to tumor therapy in clinic in the future.
Antigens, CD20 ; immunology ; Apoptosis ; Escherichia coli ; genetics ; Fermentation ; Humans ; Immunoglobulin Fab Fragments ; chemistry ; genetics ; isolation & purification ; therapeutic use ; Lymphoma, B-Cell ; therapy ; Plasmids ; Recombinant Fusion Proteins ; biosynthesis ; isolation & purification ; therapeutic use

In order to develop tools for an early serodiagnosis of Plasmodium falciparum infection, we evaluated the usefulness of P. falciparum liver stage antigen-3 (LSA-3) as a serodiagnostic antigen. A portion of LSA-3 gene was cloned, and its recombinant protein (rLSA-3) was expressed in Escherichia coli and purified by column chromatography. The purified rLSA-3 and 120 test blood/serum samples collected from inhabitants in malaria-endemic areas of Mandalay, Myanmar were used for this study. In microscopic examinations of blood samples, P. falciparum positive rate was 39.1% (47/120) in thin smear trials, and 33.3% (40/120) in thick smear trials. Although the positive rate associated with the rLSA-3 (30.8%) was lower than that of the blood stage antigens (70.8%), rLSA-3 based enzyme-linked immunosorbent assay could detect 12 seropositive cases (10.0%), in which blood stage antigens were not detected. These results indicate that the LSA-3 is a useful antigen for an early serodiagnosis of P. falciparum infection.
Recombinant Proteins/biosynthesis/genetics/*immunology ; Plasmodium vivax/isolation & purification ; Plasmodium falciparum/*immunology ; Molecular Sequence Data ; Malaria, Falciparum/blood/*diagnosis ; Humans ; Genes, Protozoan/genetics/immunology ; Fluorescent Antibody Technique, Direct/methods ; Escherichia coli/genetics ; Enzyme-Linked Immunosorbent Assay/methods ; Early Diagnosis ; DNA, Protozoan/chemistry ; DNA Primers/chemistry ; Cloning, Molecular/methods ; Base Sequence ; Antigens, Protozoan/biosynthesis/chemistry/genetics/*immunology ; Animals ; Amino Acid Sequence

OBJECTIVETo clone migfilin-N terminal sequence into E.coli and obtain a fusion protein for preparing rabbit polyclonal antibody against migfilin, thereby facilitating the study of the role of migfilin in the biological behavior of colon cancer.

METHODSBased on human migfilin cDNA sequence, a pair of primers was designed to amplify migfilin-N terminal sequence by PCR. The PCR product was subcloned into the bacterial expression vector pGEX-4T-1 with EcoRI/XhoI sites, and the target recombinant plasmids were identified with enzymatic cleavage followed by DNA sequence analysis. By transforming the expression vector into component E.coli BL(21) cells, the GST-migfilin-N fusion protein was expressed with IPTG induction. Glutathione-sepharose beads were used to purify the fusion protein, and anti-migfilin polyclonal antibody was produced by immunization of rabbits with the purified GST-migfilin N-terminal fusion protein. The resultant anti-migfilin polyclonal antibody was purified by protein A beads and used for Western blotting for detecting migfilin expression in different cell lines.

RESULTS AND CONCLUSIONThe migfilin-N terminal gene fragment was cloned successfully, and purified GST-migfilin N-terminal fusion protein and anti-rabbit migfilin polyclonal antibodies were obtained. Western blot analysis demonstrates that the antibodies specifically detected migfilin expression in the cell lines, which may facilitate further investigation of the role of migfilin in the biology of colon cancer.

Animals ; Antibodies, Monoclonal ; biosynthesis ; immunology ; isolation & purification ; Base Sequence ; Blotting, Western ; Cell Adhesion Molecules ; genetics ; immunology ; Cell Line, Tumor ; Cloning, Molecular ; Colonic Neoplasms ; genetics ; metabolism ; pathology ; Cytoskeletal Proteins ; genetics ; immunology ; DNA, Complementary ; chemistry ; genetics ; Escherichia coli ; genetics ; Humans ; Molecular Sequence Data ; Rabbits ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; immunology ; Reverse Transcriptase Polymerase Chain Reaction ; Sequence Analysis, DNA