Explore the vast range of titles available.

We report the immunogenicity of three dendrimeric peptide vaccine candidates for classical swine fever virus (CSFV). Each dendrimeric construct contained four copies of a B-cell epitope from the E2 glycoprotein of CSFV [construct 1: E2 (694–712); 2: E2 (712–727); 3: E2 (829–842)] joined to a T-cell epitope from the NS3 protein (residues 1446–1460). Intramuscular immunization of domestic pigs with the different constructs significantly reduced the clinical score after lethal challenge with CSFV. In contrast, control pigs developed severe clinical signs of the disease. All pigs vaccinated with construct 1, containing a B-cell epitope from the E2 B–C domain, developed an antibody response that recognized not only the original dendrimeric immunogen but also its constituting E2 epitope in linear form, albeit no neutralizing antibodies were detected prior to viral challenge. Two of these pigs were partially protected, which associated with the induction of IFN-γ producing cells and of neutralizing antibodies upon challenge. Interestingly, the serological response elicited by construct 1 lacked antibodies to E2 A domain, used as infection markers. The dendrimeric approach could therefore provide a basis for the development of CSFV marker (DIVA) vaccines, and contribute to a better understanding of the immune responses against CSFV.

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by a progressive amyloid-β accumulation, loss of cognitive abilities, and synaptic alterations. Given the remarkable recovery of cognition in AD models of targeting-Aβ immunotherapy, we sought to determine the molecular correlate(s) associated with improvement. We evaluated the efficacy of a recombinant chimeric 6Aβ15-T antigen formulated with alum adjuvant as a novel Aβ B-cell epitope vaccine (rCV01) in 3 × Tg-AD mice. rCV01 elicited robust Th2-polarized Aβ-specific antibodies without autoimmune T cell responses in 3 × Tg-AD mice. The long-lasting anti-Aβ42 antibodies were associated with markedly reduced AD-like pathology, enhanced synaptic function, and improved cognitive performance in aged 3 × Tg-AD mice. This is the first report to provide one hypothesis for the improved outcomes following vaccination is a reduction in the levels of active calpain in rCV01-immunized AD mice, which is likely attributable to preventing dynamin 1 and PSD-95 degradation allowing functional recovery of cognition. rCV01 is a highly immunogenic recombinant chimeric 6Aβ15-T vaccine that shows clear neuroprotective properties in preclinical mouse models of AD and is a candidate for an effective AD vaccine.

Swine influenza virus (SIV) is an important viral pathogen in pig populations. However, commercial vaccines cannot provide complete protection with induced humoral immunity only, and require frequent updates to fight against current isolates. DNA vaccination is an effective means of eliciting both arms of the immune system, the humoral and cellular immune responses. In this study, DNA vector pcDNA3.1 was inserted with a chimeric intron downstream of the CMV promoter region followed by a Kozak sequence to enhance the expression of gene inserts. The C-terminal of the VP22 gene (VP22c), encoding the tegument protein of bovine herpesvirus-1, was fused separately to the N-terminal of four quadruplicated epitopes: two B-cell epitopes (HA91-108 and M2e), and two T-cell epitopes (NP366-374 and NP380-393), which were conserved, at least among the three SIV subtypes prevailing in pig populations in North America. Linker -KK- was used to space between each copy of the two B-cell epitopes, and -RVKR- was used for the two T-cell epitopes, in order to enhance the presentation of epitopes to the immune system. The expression of epitopes was confirmed in in vitro transfection of 293FT cells, and higher percentages of epitope-positive cells were achieved from the plasmids containing VP22c than those without. After the DNA plasmids were administered to mice intramuscularly in combination or separately, or boosted with recombinant proteins of quadruplicated epitopes fused to VP22c, the vaccine stimulated the desired epitope-specific humoral immunity to the two B-cell epitopes, and cellular immunity to the epitope NP380-393. Our results indicate that plasmids with quadruplicated epitopes fused to the VP22c may be a potential vehicle in developing epitopes as vaccines against SIV.

Plague is a zoonotic disease caused by Yersinia pestis, an etiological agent of pneumonic and bubonic plague. There is a need for an improved plague vaccine that may overcome the limitation of presently available whole cell vaccine. An alternative approach described here, is the use of protective epitopes from immunodominant antigen of Y. pestis. One such antigen is the F1 antigen, a major envelope and virulent protein that possess antiphagocytic and anti-microbial properties. The present study was aimed to develop a peptide-based vaccine, based upon the constructs made between B and T cell epitopes of F1 antigen of Y. pestis. The immunogenicity, IgG subclass pattern, affinity, avidity and in vivo protective efficacy of the antibodies generated for different B-T constructs were studied in murine model using microsphere as the delivery vehicle. The mode of immunization was both intranasal and intramuscular, with single and multiple doses of immunization, respectively. Intranasal immunization generated consistent high titre and long lasting immune response both for IgG and IgA in sera and sIgA in washes while intramuscular route generated peak IgG levels in sera only. The IgG isotypic levels pattern showed higher IgG2a/IgG2b levels in intranasal route while mixed isotypic levels of IgG1, IgG2a/IgG2b were observed in intramuscular route. The affinity and relative avidity of antibodies showed best results with intranasal route as compared to the intramuscular route. The specific activity measurement (IgG/IgA content) in sera and washes were well correlated with the antibody levels. Finally, in vivo protective studies showed that B1T1 and B2T1 conjugates protected the mice till day 15 while rest of the conjugates showed poor protection.

Vaccine strategies that stimulate the ocular mucosal immune system (OMIS), the immune barrier that protects the surface of the eye are needed. However, most vaccines fail to induce local ocular immune responses and, in the absence of adjuvant, may induce a state of immunological tolerance. In this study, we present a new vaccine strategy that consists of ocular mucosal (OM) delivery of peptide epitopes, selected from the herpes simplex virus (HSV-1) glycoprotein D (gD) mixed with synthetic immunostimulatory oligodeoxynucleotides (ODNs) containing unmethylated CpG motifs (CpG 2007). Repeated topical ocular application of gD peptide epitopes and CpG 2007 induced peptide-specific and virus-neutralizing IgA/IgG in tears as well as in serum. As a second marker, generation of local and systemic peptide- and virus-specific T cells confirmed the potent immunogenicity of peptides-CpG 2007 formulation when applied through the OM route. Moreover, OM delivery of peptides-CpG 2007 induced local IFN-γ and IL-2 responses and low IL-4 production, demonstrating the polarization towards a Th1 response. Immunization, using free CpG 2007 ODNs or peptides alone did not produce OMIS stimulation. This novel vaccine strategy may be key for ocular infectious pathogens, such as HSV-1, that require both secretory antibody and the Th1 responses. The results suggest the clinical feasibility of developing an OM delivery system using epitope-based vaccines.

Subunit vaccines commonly lack sufficient immunogenicity to stimulate a comprehensive protective immune response in vivo. We have investigated the potential of specific cytokines (interleukin-2) and particulate delivery systems (liposomes) to enhance antigenicity. Here we report that the IgG1 and IFN-γ responses to a subunit antigen, consisting of a T and B-cell epitope from Influenza haemagglutinin, can be improved when it is both fused to interelukin-2 and encapsulated in liposomes. However, this vaccine formulation was not able to protect animals against a challenge with live Influenza A/PR/8/34 virus. The addition of more potent immune stimulators may be necessary to improve responses.

The primary two-dose SARS-CoV-2 mRNA vaccine series are strongly immunogenic in humans, but the emergence of highly infectious variants necessitated additional doses and the development of vaccines aimed at the new variants 1 – 4 . SARS-CoV-2 booster immunizations in humans primarily recruit pre-existing memory B cells 5 – 9 . However, it remains unclear whether the additional doses induce germinal centre reactions whereby re-engaged B cells can further mature, and whether variant-derived vaccines can elicit responses to variant-specific epitopes. Here we show that boosting with an mRNA vaccine against the original monovalent SARS-CoV-2 mRNA vaccine or the bivalent B.1.351 and B.1.617.2 (Beta/Delta) mRNA vaccine induced robust spike-specific germinal centre B cell responses in humans. The germinal centre response persisted for at least eight weeks, leading to significantly more mutated antigen-specific bone marrow plasma cell and memory B cell compartments. Spike-binding monoclonal antibodies derived from memory B cells isolated from individuals boosted with either the original SARS-CoV-2 spike protein, bivalent Beta/Delta vaccine or a monovalent Omicron BA.1-based vaccine predominantly recognized the original SARS-CoV-2 spike protein. Nonetheless, using a more targeted sorting approach, we isolated monoclonal antibodies that recognized the BA.1 spike protein but not the original SARS-CoV-2 spike protein from individuals who received the mRNA-1273.529 booster; these antibodies were less mutated and recognized novel epitopes within the spike protein, suggesting that they originated from naive B cells. Thus, SARS-CoV-2 booster immunizations in humans induce robust germinal centre B cell responses and can generate de novo B cell responses targeting variant-specific epitopes. COVID-19 booster immunizations aimed at spike protein from new SARS-CoV-2 variants induce robust germinal centre B cell responses against the original spike protein, as well as de novo B cell responses against the variant spike protein.

The ongoing pandemic of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a major threat to global health 1 and the medical countermeasures available so far are limited 2 , 3 . Moreover, we currently lack a thorough understanding of the mechanisms of humoral immunity to SARS-CoV-2 4 . Here we analyse a large panel of human monoclonal antibodies that target the spike (S) glycoprotein 5 , and identify several that exhibit potent neutralizing activity and fully block the receptor-binding domain of the S protein (S RBD ) from interacting with human angiotensin-converting enzyme 2 (ACE2). Using competition-binding, structural and functional studies, we show that the monoclonal antibodies can be clustered into classes that recognize distinct epitopes on the S RBD , as well as distinct conformational states of the S trimer. Two potently neutralizing monoclonal antibodies, COV2-2196 and COV2-2130, which recognize non-overlapping sites, bound simultaneously to the S protein and neutralized wild-type SARS-CoV-2 virus in a synergistic manner. In two mouse models of SARS-CoV-2 infection, passive transfer of COV2-2196, COV2-2130 or a combination of both of these antibodies protected mice from weight loss and reduced the viral burden and levels of inflammation in the lungs. In addition, passive transfer of either of two of the most potent ACE2-blocking monoclonal antibodies (COV2-2196 or COV2-2381) as monotherapy protected rhesus macaques from SARS-CoV-2 infection. These results identify protective epitopes on the S RBD and provide a structure-based framework for rational vaccine design and the selection of robust immunotherapeutic agents. An analysis identifies human monoclonal antibodies that potently neutralize wild-type SARS-CoV-2 and protect animals from disease, including two that synergize in a cocktail, suggesting that these could be candidates for use as therapeutic agents for the treatment of COVID-19 in humans.

Germinal centres are the engines of antibody evolution. Here, using human immunodeficiency virus (HIV) Env protein immunogen priming in rhesus monkeys followed by a long period without further immunization, we demonstrate germinal centre B (B GC ) cells that last for at least 6 months. A 186-fold increase in B GC cells was present by week 10 compared with conventional immunization. Single-cell transcriptional profiling showed that both light- and dark-zone germinal centre states were sustained. Antibody somatic hypermutation of B GC cells continued to accumulate throughout the 29-week priming period, with evidence of selective pressure. Env-binding B GC cells were still 49-fold above baseline at 29 weeks, which suggests that they could remain active for even longer periods of time. High titres of HIV-neutralizing antibodies were generated after a single booster immunization. Fully glycosylated HIV trimer protein is a complex antigen, posing considerable immunodominance challenges for B cells 1 , 2 . Memory B cells generated under these long priming conditions had higher levels of antibody somatic hypermutation, and both memory B cells and antibodies were more likely to recognize non-immunodominant epitopes. Numerous B GC cell lineage phylogenies spanning more than the 6-month germinal centre period were identified, demonstrating continuous germinal centre activity and selection for at least 191 days with no further antigen exposure. A long-prime, slow-delivery (12 days) immunization approach holds promise for difficult vaccine targets and suggests that patience can have great value for tuning of germinal centres to maximize antibody responses. Using HIV Env protein immunogen priming in rhesus monkeys followed by a long period without further immunization, we demonstrate germinal centre B cells lasting at least 6 months, showing promise in regard to difficult vaccine targets.

Background Norovirus (NoVs) is a foodborne pathogen that causes acute gastroenteritis. The diversity of its principal antigenic protein poses a significant challenge to vaccine development and the prevention of large-scale outbreaks globally. Currently, no licensed vaccines against norovirus have been approved. Methods We developed a novel pipeline that integrates multiple bioinformatics tools to design broad-spectrum vaccines against NoVs. Specifically, broad-spectrum T-cell epitope vaccines were designed based on consensus sequences and optimized epitope screening, while broad-spectrum B-cell spatial epitope vaccines were constructed using high-throughput antigenicity calculations and epitope mapping. Results This pipeline underwent rigorous validation at three levels: firstly, In silico validation: Analysis of properties and structures demonstrated the appropriateness of amino acid composition and the structural integrity of the vaccine sequences. Secondly, theoretical assessment: Evaluation of human leukocyte antigen (HLA) subtype and antigenicity coverage indicated a broad theoretical protective spectrum for the designed vaccine immunogens. Furthermore, in silico simulation confirmed their ability to elicit an immune response. Finally, animal-level validation: Experiments in mice showed that both vaccine immunogens stimulated high levels of IgG and IgA. Notably, Vac-B induced a strong IgG response against GII.2 and a robust IgA response against GII.17, comparable to the immune response elicited by the wild-type NoV non-replicating virus-like particle (VLP) protein group. Conclusions Both in silico and in vivo experimental findings suggest that the proposed pipeline and vaccine immunogens could serve as valuable theoretical guidance for the development of multi-epitope vaccines against NoVs.