Design and antitumor activity of programmed cell death ligand 1 epitope peptide vaccine / 中国药科大学学报

@#Several programmed cell death protein 1 (PD-1) or its ligand (PD-L1) immune checkpoint blocking antibodies are available for clinical treatment, but only some patients show clinical response, so an alternative strategy for tumor immunotherapy is needed.A therapeutic tumor vaccine targeting PD-L1 is a meaningful attempt.In this study, we designed an epitope peptide vaccine targeting PD-L1, and then screened the immunogenic PD-L1 epitope peptide based on the humanized immune system (HIS) mouse model and further investigated its anti-tumor activity.The results show that the designed and screened PD-L1-B1 epitope peptide vaccine not only successfully induced PD-L1-specific humoral and cellular immunity, but also exhibit anti-tumor activity.In addition, immunotherapy increased T-lymphocyte infiltration of tumors and reshaped the tumor immunosuppressive microenvironment.In conclusion, PD-L1-B1 epitope peptide vaccine exhibits potent anti-tumor activity and may be an effective alternative immunotherapeutic strategy for patients insensitive to PD-1/PD-L1 blockade.

Prokaryotic expression of the GapC protein of Streptococcus uberis and prediction, identification of its B-cell epitopes / 生物工程学报

The GapC protein of Streptococcus uberis located on the surface of bacteria is a protein with glyceraldehyde-3-phosphate dehydrogenase activity. It participates in cellular processes and exhibits a variety of biological activities. In addition, it has good antigenicity. The aim of this study was to predict the possible B-cell epitopes of the GapC protein and verify the immunogenicity of candidate epitope peptides. The gapC gene of S. uberis isolate RF5-1 was cloned into a recombinant expression plasmid pET-28a-GapC and inducibly expressed. The purified protein was used to immunize experimental rabbits to produce anti-GapC polyclonal antibodies. The three-dimensional structure and three-dimensional location of the GapC B-cell epitopes and the homology comparison of the GapC protein and its B-cell epitopes were carried out using bioinformatics softwares. The results showed that the 44-kDa GapC protein had a good immunological reactivity. Six linear and 3 conformational dominant B-cell epitopes against the GapC protein were selected and synthesized. Three dimensional analysis indicated that the selected peptides have better antigen epitope formation potential. Rabbit anti-GapC polyclonal antibodies were generated after immunized with the purified GapC protein, and the polyclonal antibodies were used to identify the epitope peptide by an indirect ELISA. The ELISA results showed that all of the 9 epitope peptides could react with anti-GapC polyclonal antibodies with varying titers. Among them, the epitope polypeptide 266AANDSYGYTEDPIVSSD282 reacted with the polyclonal antibodies significantly stronger than with other epitope peptides. This study laid an experimental foundation for in-depth understanding of the immunological properties and utilizing effective epitopes of the GapC protein of S. uberis.

Multi-Epitope Peptide-Based and VacciniaBased Universal Influenza Vaccine Candidates Subjected to Clinical Trials

@#In light of the limited protection conferred by current influenza vaccines, immunisation using universal influenza vaccines has been proposed for protection against all or most influenza sub-types. The fundamental principle of universal influenza vaccines is based on conserved antigens found in most influenza strains, such as matrix 2, nucleocapsid, matrix 1 and stem of hemagglutinin proteins. These antigens trigger cross-protective immunity against different influenza strains. Many researchers have attempted to produce the conserved epitopes of these antigens in the form of peptides in the hope of generating universal influenza vaccine candidates that can broadly induce cross-reactive protection against influenza viral infections. However, peptide vaccines are poorly immunogenic when applied individually owing to their small molecular sizes. Hence, strategies, such as combining peptides as multi-epitope vaccines or presenting peptides on vaccinia virus particles, are employed. This review discusses the clinical and laboratory findings of several multi-epitope peptide vaccine candidates and vaccinia-based peptide vaccines. The majority of these vaccine candidates have reached the clinical trial phase. The findings in this study will indeed shed light on the applicability of universal influenza vaccines to prevent seasonal and pandemic influenza outbreaks in the near future.

Recombinant DNA and Protein Vaccines for Foot-and-mouth Disease Induce Humoral and Cellular Immune Responses in Mice

BACKGROUND: Foot-and-mouth disease virus (FMDV) is a small single-stranded RNA virus which belongs to the family Picornaviridae, genus Apthovirus. It is a principal cause of FMD which is highly contagious in livestock. In a wild type virus infection, infected animals usually elicit antibodies against structural and non-structural protein of FMDV. A structural protein, VP1, is involved in neutralization of virus particle, and has both B and T cell epitopes. A RNA-dependent RNA polymerase, 3D, is highly conserved among other serotypes and strongly immunogenic, therefore, we selected VP1 and 3D as vaccine targets. METHODS: VP1 and 3D genes were codon-optimized to enhance protein expression level and cloned into mammalian expression vector. To produce recombinant protein, VP1 and 3D genes were also cloned into pET vector. The VP1 and 3D DNA or proteins were co-immunized into 5 weeks old BALB/C mice. RESULTS: Antigen-specific serum antibody (Ab) responses were detected by Ab ELISA. Cellular immune response against VP1 and 3D was confirmed by ELISpot assay. CONCLUSION: The results showed that all DNA- and protein-immunized groups induced cellular immune responses, suggesting that both DNA and recombinant protein vaccine administration efficiently induced Ag-specific humoral and cellular immune responses.

Polylatic acid microspheres-induced CTL cytotoxicity against hepatocellular carcinoma cell lines / 中国肿瘤生物治疗杂志

Objective: To investigate the in vitro efficiency of two kinds of polylatic acid (PLA) immunomicrospheres: M1(hAFP158~166)and M2(hAFP218~226) in specific inducement of CTL and the cytotoxicity of CTL against hepatocellular carcinoma cells. Methods: Pripheral blood monocytes (PBMC) of HLA-A2+ healthy volunteers stimulated in vitro by peptide-loading microspheres were taken as effectors. The experiments were divided into three groups: control group, hAFP+ tumor cells group, and hAFP- tumor cells group. The specific cytolysis of target cells was assessed by 51Cr-release assay. Results: Both M1 and M2 induced proliferation of HLA-A2+ PBMC, forming visible clones. The effector cells induced by M1 and M2 both had an cytolysis rate over 75% for hAFP+ tumor cells, which was significantly higher than that for hAFP- tumor cells (P0.05). Conclusion: The two kinds of microspheres can both induce specific CTL in vitro, which can effectively kill hAFP+ tumor cells.