Molecular cloning and expression analysis of porcine gamma-interferon-inducible lysosomal thiol reductase (GILT).

A porcine interferon-gamma-inducible lysosomal thiol reductase (GILT) cDNA, designated pGILT, was cloned by RT-PCR and rapid amplification of cDNA ends (RACE) strategies. The full-length cDNA of pGILT consists of 1,062 bp with a 741 bp open reading frame, encoding 246 amino acids, with a putative molecular weight of 29.5 kDa. The deduced pGILT possesses the typical structural feature of mammalian GILT, including an active-site CXXC motif, a GILT signature sequence CQHGX(2)ECX(2)NX(4)C, and 10 conserved cysteines. The genomic DNA sequence of pGILT contains seven exons and six introns, which is similar to vertebrate GILT exon-intron organization. The result of real-time PCR showed that GILT is expressed in many tissues in the pig, including spleen, liver, lung, heart, intestine, blood and kidney. And the pGILT expression is obviously up-regulated in spleen and blood after induction with LPS. These results suggesting that pGILT is highly likely to play a role in the innate immune responses in porcine. It also provided the basis for investigations on the role of GILT in this important domestic species and an animal model for human diseases.

Expression, purification and characterization of anti-BAFF antibody secreted from the yeast Pichia pastoris.

B-Cell activating factor (BAFF) is critical for B cell survival and maturation; excessive expression of it corrupts B-cell tolerance and may lead to autoimmunity. The gene, scFv-Fc, coding for the antibody of BAFF was inserted into the eukaryotic expression vector, pPICZalphaA, and transformed into Pichia pastoris. A high-level expression strain was obtained using a 'yeastern blotting' method. The scFv-Fc antibody was purified and 56 mg was obtained from 1 l of culture supernatant. It retained high binding activity to both soluble BAFF and membrane-bound BAFF.

Construction of bifunctional fusion proteins consisting of duck BAFF and EGFP.

We constructed fusion proteins consisting of fluorescence-enhanced green fluorescent protein (EGFP) and soluble domain of duck B-cell-activating factor of the TNF family (dsBAFF). The soluble EGFP/dsBAFF was efficiently expressed in Escherichia coli BL 21 (DE3) and was purified in milligram amounts using metal chellate affinity chromatography. The fusion protein exhibited similar fluorescence spectra with free EGFP and promoted the survival of duck bursal B cells in vitro as well as dsBAFF. EGFP/dsBAFF has shown specific binding to duck BAFF receptors positive-cells and the stained cells could be analyzed with flow cytometry. Thus, the fusion protein represents a readily obtainable source of biologically active dsBAFF that may prove useful in further studies on duck BAFF and its receptors.

Molecular cloning and expression analysis of interferon-gamma-inducible-lysosomal thiol reductase gene in orange-spotted grouper, Epinephelus coioides.

In mammals, interferon-gamma-inducible-lysosomal thiol reductase (GILT) has been demonstrated to play a key role in the processing and presentation of MHC class II-restricted antigen (Ag) by catalyzing disulfide bond reduction, thus unfolding native protein Ag and facilitating subsequent cleavage by proteases. In this study a cDNA containing the orange-spotted grouper GILT (OsgGILT) coding sequence has been cloned and its complete sequence determined. The full-length cDNA of OsgGILT gene is 1066 bp nucleotides (nt) encoding a protein of 260 amino acids (aa), with a putative molecular weight of 28.7 kDa. The deduced OsgGILT possesses the typical structural feature of mammalian GILT, including an active-site CXXC motif, a GILT signature sequence CQHGX(2)ECX(2)NX(4)C, and 10 conserved cysteines. The result of real-time PCR showed that OsgGILT mRNA was expressed in heart, liver, brain, gill, kidney and muscle and more highly expressed in spleen. The OsgGILT expression is obviously up-regulated in spleen and kidney after induction with LPS, these results suggest that OsgGILT may be involved in the immune response to LPS challenge in orange-spotted grouper.

cDNA cloning, expression and bioactivity of porcine BAFF.

B cell activating factor belonging to the tumor necrosis factor (TNF) family (BAFF) is critical for B cell survival, maturation and T cell activation by acting through its three receptors, BAFF-R, BCMA and TACI. In the present study, a porcine BAFF cDNA, designated pBAFF, was cloned by RT-PCR and rapid amplification of cDNA ends (RACE) strategies. The full-length cDNA of pBAFF consists of 805bp with a 702bp open reading frame, encoding 233 amino acids. The deduced amino acid sequence contains a predicted transmembrane domain and a putative furin protease cleavage site corresponding to other identified BAFF homologues. The amino acid similarity between the functional soluble parts of pBAFF and human BAFF (hBAFF) or chicken BAFF (cBAFF) is 93% and 85%, respectively, with identity at the amino acid level was 88% and 76%, respectively. The characteristic of the three-cysteine residues of BAFF is conserved in pBAFF. RT-PCR showed that BAFF is expressed in many tissues in the pig, including spleen, liver, lung, heart, intestine, kidney, thymus and PBLs. Recombinant soluble pBAFF (psBAFF) fused with His(6) tag was efficiently expressed in Escherichia coli BL21 (DE3) and its expression was confirmed by sodium dodecyl sulfate polyacrylamide gel electropheresis (SDS-PAGE) and Western blotting. In vitro, purified psBAFF co-stimulates the proliferation of not only porcine B cells but also human B cells. In addition, hsBAFF binds to porcine B cells and has a positive effect on their proliferation. These findings indicate pBAFF plays an important role in proliferation of porcine B cells and functional cross-reactivity occurs between porcine and human BAFF. In vitro expression of bioactive psBAFF provides the basis for further investigation of its potential to be used as an immunoadjuvant for enhancing vaccine efficacy and an immunotherapeutic in pig. It also provides the basis for investigations on the role of BAFF in this important domestic species and an animal model for human diseases.

Molecular cloning, in vitro expression and bioactivity of goose B-cell activating factor.

B-cell activating factor (BAFF), belonging to the TNF family, is critical for B cell survival and maturation. cDNA of goose BAFF (gBAFF) was amplified from goose spleen by RT-PCR. The open reading frame (ORF) of gBAFF encodes a protein of 288-amino acid. The gBAFF shows 98, 92, 44 and 55% amino acid sequence identity with duck (dBAFF), chicken (cBAFF), mouse (mBAFF) and human BAFF (hBAFF), respectively. RT-PCR results showed that gBAFF mRNA is expressed in thymus and more highly expressed in the bursa of Fabricius and spleen. Recombinant soluble gBAFF (gsBAFF) expressed in Escherichia coli has molecular weight of approximately 19kDa. In vitro, purified gsBAFF was able to promote bursa B cells survival/proliferation in goose, duck and chicken. Furthermore, recombinant dsBAFF and csBAFF have a positive effect on goose, duck and chicken bursa B cells survival/proliferation. These findings indicate that gBAFF plays an important role in the survival/proliferation of goose B cells and, owing to its high evolutionary conservation, functional cross-reactivity exists between chicken, duck and goose BAFF.

Expression in Escherichia coli and purification of bioactive antibacterial peptide ABP-CM4 from the Chinese silk worm, Bombyx mori.

The antibacterial peptide CM4 (ABP-CM4), isolated from Chinese Bombys mori, is a 35-residue cationic, amphipathic alpha-helical peptide that exhibits a broad range of antimicrobial activity. To explore a new approach for the expression of ABP-CM4 in E. coli, the gene ABP-CM4, obtained by recursive PCR (rPCR), was cloned into the vector pET32a to construct a fusion expression plasmid. The fusion protein Trx-CM4 was expressed in soluble form, purified by Ni(2+)-chelating chromatography, and cleaved by formic acid to release recombinant CM4. Purification of rCM4 was achieved by affinity chromatography and reverse-phase HPLC. The purified of recombinant peptide showed antimicrobial activities against E. coli K(12)D(31), Penicillium chrysogenum, Aspergillus niger and Gibberella saubinetii. According to the antimicrobial peptide database (http://aps.unmc.edu/AP/main.html), 116 peptides contain a Met residue, but only 5 peptides contain the AspPro site, indicating a broader application of formic acid than CNBr in cleaving fusion protein. The successful application to the expression of the ABP-CM4 indicates that the system is a low-cost, efficient way of producting milligram quantities of ABP-CM4 that is biologically active.

Cloning, expression and bioactivity of duck BAFF.

B cell activating factor (BAFF) belonging to the TNF family is critical for B cell survival and maturation. In the present study, we identified a duck BAFF cDNA, named dBAFF, by RT-PCR and RACE strategies. The open reading frame (ORF) of this cDNA encodes a 288-amino acid protein containing a predicted transmembrane domain and a putative furin protease cleavage site like chicken BAFF (cBAFF), human BAFF (hBAFF) and mouse BAFF (mBAFF). The amino acid identity between biologically soluble dBAFF and cBAFF, hBAFF or mBAFF is 97, 78 and 71%, respectively. RT-PCR analysis showed the dBAFF gene is strongly expressed in the bursa of fabricius. Recombinant soluble dBAFF (dsBAFF) fused with NusA.tag was efficiently produced in Origami B (DE3) pLysS expression host strain. In vitro, purified dsBAFF was not only able to promote survival of bursa B cells, but also able to co-stimulate proliferation of mammalian B cells with anti-IgM. Furthermore, recombinant hsBAFF has a positive effect on duck bursa B cells survival. These findings indicate dBAFF plays an important role in survival and proliferation of duck B cells and because of its high conservation in the evolution, functional cross-reactivity exists between mammalian and duck BAFF.