Optimization of coding sequences and expression of antimicrobial peptide magainin II in Escherichia coli and Pichia pastoris / 生物工程学报

The antimicrobial peptide magainin II is expressed in the skin of the African clawed frog, Xenopus laevis, and exhibits a broad spectrum of antimicrobial activity as well as tumoricidal properties at low concentrations. In addition, magaininII plays a synergistic role during antimicrobial and tumoricidal processes with another antimicrobial peptide PGLa that is also expressed in Xenopus laevis. The optimized cDNA sequence of magainin II and magainin II-PGLa hybrid peptide according to E. coli or Pichia pastoris codon usage frequency were synthesized and sub-cloned into prokaryotic expression vector pGEX and Pichia pastoris secreted expression vector pPIC9k. The resulting recombinant plasmids were named as pGEX-magainin II and pPIC9k-magainin II-PGLa. The GST-magainin II fusion protein was highly expressed in E. coli. Furthermore, magainin II was successfully purified by digestion with PreScission Protease to cleave the GST tag. Additionally, our data obtained from the ELISA revealed that magainin II -PGLa hybrid peptide was successfully expressed in Pichia pastoris. These experiments establish a useful system for further studies of these antimicrobial peptides.

Immunological efficiency induced by HIV-1 p24 DNA combined with P24 protein / 生物工程学报

New strategies to improve vaccine efficacy against human immunodeficiency virus type 1 (HIV-1) are still required. DNA vaccines, exhibiting potential advantages over conventional vaccines for their simplicity and versatility, can induce specific humoral and cellular immune responses. We developed a recombinant pVAX1 DNA vector carrying p24 gene of HIV-1. The results showed that pVAX1 mediated gene possessed the ability of effective expression in both transfected 293T cells and BALB/c mice. And pVAX1-p24 DNA prime and boost immunization can induce significant P24-specific humoral immune responses and cellular immune responses in BALB/c mice. Furthermore, immunization with pVAX1-p24 DNA prime and protein boost induced 7.3 to 8.0-fold greater p24-specific humoral responses than pVAX1-p24 DNA prime and boost, while the cellular immune responses induced by combined immunization was lower. The results suggested that pVAX1-p24 DNA and P24 protein vaccine is a promising HIV-1 vaccine, and the selections of the immunization strategies are important for the immunization results.