Immunomodulatory activity of polycaprolactone nanoparticles with calcium phosphate salts against Leishmania infantum infection

Objective:To prepare and characterize polycaprolactone(PCL)nanoparticles loaded with sonicator fragmented(SLA)and freeze-thaw Leishmania antigens(FTLA)and to investigate the in vitro immunogenicity of antigen-encapsulated nanoparticles with calcium phosphate adjuvant.Methods:The water/oil/water binary emulsion solvent evaporation method was used to synthesize antigen-loaded PCL nanoparticles.Particles were characterized by scanning electron microscopy and zeta potential measurements.Their cytotoxicity in J774 macrophages in vitro was determined by MTT analysis.In addition,the amount of nitric oxide and the level of cytokines produced by macrophages were determined by Griess reaction and ELISA method,respectively.The protective effect of the developed formulations was evaluated by determining the infection index percentage in macrophages infected with Leishmania infantum.Results:Compared to the control group,SLA PCL and FTLA PCL nanoparticles with calcium phosphate adjuvant induced a 6-and 7-fold increase in nitric oxide,respectively.Additionally,the vaccine formulations promoted the production of IFN-γand IL-12.SLA PCL and FTLA PCL nanoparticles combined with calcium phosphate adjuvant caused an approximately 13-and 11-fold reduction in infection index,respectively,compared to the control group.Conclusions:The encapsulation of antigens obtained by both sonication and freeze-thawing into PCL nanoparticles and the formulations with calcium phosphate adjuvant show strong in vitro immune stimulating properties.Therefore,PCL-based antigen delivery systems and calcium phosphate adjuvant are recommended as a potential vaccine candidate against leishmaniasis.

Berberine improves central memory formation of CD8^(+)T cells:Implications for design of natural product-based vaccines

Berberine(BBR)as one of the most effective natural products has been increasingly used to treat various chronic diseases due to its immunosuppressive/tolerogenic activities.However,it is unknown if BBR can be applied without abrogating the efforts of vaccination.Here we show that priming of CD8^(+)T cells in the presence of BBR lead to improved central memory formation(Tcm)with substantially reduced effector proliferation,primarily orchestrated through activation of AMPK and Stat5.Tcm derived from vaccinated mice fed with BBR were able to adoptively transfer protective immunity to naIve recipients.Vaccination of BBR-fed mice conferred better memory protection against infection without losing immediate effector efficacy,suggesting appreciable benefits from using BBR in vaccination.Thus,our study may help to lay the groundwork for mechanistic understanding of the immunomodulatory effects of natural products and their potential use as adjuvant that allows the design of novel vaccines with more desirable properties.

Antimicrobial roles of phagocytosis in teleost fish:Phagocytic B cells vs professional phagocytes

The defense system of teleost fish organized on innate and adaptive immunity protects them against a wide variety of pathogenic microorganisms in the aquatic environment.Phagocytosis is one of the most effective defense strategies against microbial challenge mainly performed by classical‘professional’phagocytes(including monocytes,macrophages and granulocytes).They contain,kill and process the internalized pathogens for antigen presentation by providing antigenic ligands to initiate activation and clonal expansion of T and B cells,which bridge the innate and adaptive immunity.The discovery of phagocytic B cells in teleost fish has broken the paradigm that primary vertebrate B cells are lack of phagocytosis of particulates,as well as led to the investigation of phagocytic activity of mammalian B-1 B cells.The active phagocytic,microbicidal capabilities and antigen presentation in teleost phagocytic B cell have demonstrated to be similar as professional phagocytes,providing a potential impact on development of new vaccination strategies to prevent and control infectious diseases.In this review,we aim to address current progress on the antimicrobial role of phagocytic B cells in teleost fish by comparing it with other professional phagocytes and mammalian B-1 B cells,and provide the application prospect of phagocytic B cells in developing vaccines as well as the prevention of fish diseases.

表位结构指导免疫优势转移的HPV交叉疫苗的理性设计

In vaccine development,broadly or cross-type neutralizing antibodies(bnAbs or cnAbs)are frequently targeted to enhance protection.Utilizing immunodominant antibodies could help fine-tune vaccine immunogenicity and augment the precision of immunization strategies.However,the methodologies to capitalize on the attributes of bnAbs in vaccine design have not been clearly elucidated.In this study,we discovered a cross-type neutralizing monoclonal antibody,13H5,against human papillomavirus 6(HPV6)and HPV11.This nAb exhibited a marked preference for HPV6,demonstrating superior binding activity to virus-like particles(VLPs)and significantly higher prevalence in anti-HPV6 human serum as compared to HPV11 antiserum(90%vs.31%).Through co-crystal structural analysis of the HPV6 L1 pentamer:13H5 complex,we delineated the epitope as spanning four segments of amino acids(Phe42-Ala47,Gly172-Asp173,Glu255-Val275,and Val337-Tyr351)on the L1 surface loops.Further interaction analysis and site-directed mutagenesis revealed that the Ser341 residue in the HPV6 HI loop plays a critical role in the interaction between 13H5 and L1.Substituting Ser341 with alanine,which is the residue type present in HPV11 L1,almost completely abolished binding activity to 13H5.By swapping amino acids in the HPV11 HI loop with corresponding residues in HPV6 L1(Ser341,Thr338,and Thr339),we engineered chimeric HPV11-6HI VLPs.Remarkably,the chimeric HPV11-6HI VLPs shifted the high immunodominance of 13H5 from HPV6 to the engineered VLPs and yielded comparable neutralization titers for both HPV6 and HPV11 in mice and non-human primates.This approach paves the way for the design of broadly protective vaccines from antibodies within the main immunization reservoir.

Original Antigenic Sin on Antibody Response in SARS-CoV-2 Infection

Infection and vaccination can provide protective immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, the emergence of SARS-CoV-2 variants has persisted, leading to breakthrough infections. Owing to the original antigenic sin (OAS), variant breakthrough infection or vaccination potentially induces a stronger antibody response against the ancestral strain than to subsequent variants, as in the case of influenza. Thus, overcoming OAS is important for the development of future vaccine designs. This review summarizes the recent findings on OAS in the antibody response to SARS-CoV-2 and its variants, with an emphasis on future vaccine designs.

Sequence Similarity Analysis of Non-Self CTL Epitopes and Mouse Proteins Using Sequence Alignment

This research analyzed amino acid sequence similarity between non-self T cell epitopes recognized by mouse antibodies and mouse proteins. Using sequence alignment,we found that only 8 of 1 108 epitopes are highly similar to mouse protein sequences. The result shows that non-self T cell epitopes are not similar or have little similarity to mouse protein sequences. Furthermore,reviewing the related literature,we also found that the eight epitopes would trigger immune responses in some particular environment,which are ignored by T cells in normal condition. The result suggests that no or low-similarity peptide vaccines can reduce the chance of collateral cross-reactions and enhance the antigen-specific immune response to vaccine.

Spike protein-based epitopes predicted against SARS-CoV-2 through literature mining

Background:With the diffusion of SARS-CoV-2 around the world,human health is being threatened.As there is no effective vaccine yet,the development of the vaccine is urgently in progress.Materials and methods:Immunoinformatics methods were applied to predict epitopes from the Spike protein through mining literature associated with B-and T-cell epitopes prediction published or preprinted since the outbreak of the virus till June 1,2020.3D structure of the Spike protein were obtained(PDB ID:6VSB)for prediction of discontinuous B-cell epitopes and localization of epitopes in the hotspot regions.Results:Methods provided by the Immune Epitope Database(IEDB)server were the most frequently used to predict epitopes.Sequence alignment of the epitopes extracted from literature with the Spike protein demonstrated that the epitopes in different studies converged to multiple short hotspot regions.There were three hotspot regions found in RBD of the Spike protein harboring B-cell linear epitopes(‘RQIAPGQTGKIADYNYKLPD’,‘SYGFQPTNGVGYQ’and‘YAWNRKRISNCVA’)predicted to have high antigenicity score.Two T-cell epitopes(‘KPFERDISTEIYQ’and‘NYNYLYRLFR’)predicted to be highly antigenic in the original studies were discovered in the hotspot region.Toxicity and allergenicity analysis confirmed all the five epitopes are of non-toxin,and four of them are of non-allergen.The five epitopes identified in hotspot regions of RBD were found fully exposed based on the 3D structure of the Spike protein.Conclusion:The five epitopes we discovered from literature mining may be potential candidates for diagnostics and vaccine development against SARS-CoV-2.