ABSTRACT
Objective:To obtain a high specificity and high affinity anti-PcrV protein monoclonal antibody which can be used for the treatment of Pseudomonas aeruginosa infected.Methods: The PcrV gene was amplified by PCR using P.aeruginosa PAO1 genome DNA as the template.The expression vector(pET-28a-PcrV) was constructed and transformed into E.coli BL21(DE3).The re-combinant PcrV protein was expressed by IPTG induction and purified by Ni2+affinity chromatography.The specific binders of PcrV were screened by phage display.The genes encoding VH and VL were amplified respectively by PCR using the plasmid of positive clone as the template.Then the recombinant expression vectors were constructed and transfected into 293E cells.Monoclonal antibody were purified by the Protein A affinity resin from the culture supernatants.The affinity of antibody was detected by ELISA and the function of YG5 was verified in murine pneumonia model caused by P.aeruginosa.Results: Recombinant PcrV protein was expressed and purified.A full human monoclonal antibody(named as YG5) against PcrV was obtained by phage display.The results of ELISA showed that YG5 had a high affinity with EC50=61 ng/ml.Furthermore,it was found that YG5 could protect mice from infection caused by P.aeruginosa.Conclusion:Our findings present a novel human monoclonal antibody YG5 against PcrV,which inhibits the infection casued by P.aeruginosa and may be a potential drug for treatment of P.aeruginosa infection.
ABSTRACT
Objective:To clone and express the Staphylococcus aureus Efb(extracellular fibrinogen-binding protein) protein in Escherichia coli, to purify the expression product and prepare its functional antibody and to detect the functions of Efb protein for further studies on S.aureus infection.Methods: Efb gene was amplified by PCR using S.aureus NCTC-8325 genome DNA as template and cloned into the recombinant expression vectors pET28a. E.coli BL21(DE3) with the plasmid was induced with IPTG for protein production. The protein was purified by Ni~(2+) affinity chromatography. The function of Efb protein was determined by complement activity assay and inhibition ELISA.The polyclonal antibodies were prepared by immunizing the animals. Results: The purified recombinant Efb was obtained, which could inhibit the CH50 and AH50 effectively. The functional poly-antibodies of Efb were prepared.Conclusion:Efb could inhibit the classical pathway and alternative pathway of complement activation, and the antibodies against to Efb could block the inhibition of the classical pathway of complement activation induced by Efb.
ABSTRACT
<p><b>OBJECTIVE</b>To establish an improved procedure for isolation and identification of epitopes from a random peptide library displayed on the bacterial surface.</p><p><b>METHODS</b>Epitopes were screened from FliTrx random peptide library by a monoclonal antibody 3B9 against HBV-PreS2 protein. The enrichment was monitored in each round. Higher affinity clones were obtained by increasing the washing strength and randomly selected for sequencing and Western blot analysis.</p><p><b>RESULTS</b>Clones specifically binding to antibody were enriched in each round. Ten sequences were obtained from sixteen sequenced clones, seven of them contained the common motif RXRGXY with high homogeneity to 135-140 amio acids in HBV-PreS protein and have positive results in Western blot analysis. The other three sequences have no typical motif RXRGXY and showed different Western blot results.</p><p><b>CONCLUSIONS</b>It's easy and quick to drive epitopes from a random peptide library displayed on the bacterial surface.</p>