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To further elucidate the mechanism of action and binding properties of eptinezumab to calcitonin gene-related peptide (CGRP), X-ray crystallography, computational alanine scanning, and molecular dynamics were used. X-ray diffraction data were collected to determine the three-dimensional structures of the unbound eptinezumab antigen-binding fragment (Fab) and the Fab:CGRP complex. Molecular dynamics simulations were performed to analyze the transition between uncomplexed and complex states. The amidated C-terminus of CGRP was shown to bind in a pocket formed by the Fab heavy and light chains. There was extensive contact between all six complementarity-determining regions (CDRs; composed of light-chain [L1, L2, and L3] and heavy-chain [H1, H2, H3]) of eptinezumab and CGRP. The complex demonstrated a high ligand-binding surface area dominated by aromatic residues. CDR L3 contains a disulfide bond that stabilizes the loop, contributes surface area to the binding pocket, and provides van der Waals contacts. Comparison of the uncomplexed and complex structures revealed motion near the binding cleft. The CDR loops H2 and H3 were displaced ~1.4–2.0 Å and residue H-Tyr33 changed conformation, creating a ‘latch-and-lock’ mechanism for binding CGRP and preventing dissociation. Computational alanine scanning of CGRP identified energetic ‘hot spots’ that contribute to binding energy; mutating these positions to residues in homologous neuropeptides resulted in unfavorable binding energies. The attributes of the Fab region and the conformational changes that occur in eptinezumab during binding to CGRP contribute to the specificity, durability, and strength of the interaction, and likely underlie the rapid and sustained migraine preventive effect observed in clinical studies., Graphical abstract

Hepatitis E virus (HEV) infection is a major cause of acute hepatitis but also provokes chronic infection in immunocompromised patients. Although the pathogenesis and treatment outcome involve complex interplay between the virus and host, the nature of adaptive responses of HEV to the host immune system remain obscure at best. In this study, we used large-scale proteomic bioinformatics to profile characteristic mutations in human HEV isolates associated to ribavirin treatment failure, chronic hepatitis, hepatic failure or altered immunoreactivity. The prevalence of specific mutations was examined in a large number of protein sequences of ORF1 and ORF2 regions of the 3 major human-derived HEV genotypes (1, 3 and 4). By analyzing potential B, CD4+ and CD8+ T cell epitopes, we found that many of these mutations overlap with the predicted epitopes and are frequently present among the 3 HEV genotypes. These overlapping mutations mediate reduced antigenicity. Finally, by delineation of diversification and evolution of the underlying epitopes, we observe that most of these variants apparently evolved earlier in genotype 1 when compared with genotypes 3 and 4. These results indicate that HEV is under substantial evolutionary pressure to develop mutations enabling evasion of the host immune response and resistance to antiviral treatment. This indicates the existence of an ongoing evolutionary arms race between human immunity, antiviral medication and HEV.

We performed epitope mapping studies on the major surface glycoprotein (GP) of Ebola virus (EBOV) using Chemically Linked Peptides on Scaffolds (CLIPS), which form linear and potential conformational epitopes. This method identified monoclonal antibody epitopes and predicted additional epitopes recognized by antibodies in polyclonal sera from animals experimentally vaccinated against or infected with EBOV. Using the information obtained along with structural modeling to predict epitope accessibility, we then constructed 2 DNA vaccines encoding immunodominant and subdominant epitopes predicted to be accessible on EBOV GP. Although a construct designed to produce a membrane-bound oligopeptide was poorly immunogenic, a construct generating a secreted oligopeptide elicited strong antibody responses in mice. When this construct was administered as a boost to a DNA vaccine expressing the complete EBOV GP gene, the resultant antibody response was focused largely toward the less immunodominant epitopes in the oligopeptide. Taken together, the results of this work suggest a utility for this method for immune focusing of antibody responses elicited by vaccination.

Computational vaccine design, also known as computational vaccinology, encompasses epitope mapping, antigen selection and immunogen design using computational tools. The iVAX toolkit is an integrated set of tools that has been in development since 1998 by De Groot and Martin. It comprises a suite of immunoinformatics algorithms for triaging candidate antigens, selecting immunogenic and conserved T cell epitopes, eliminating regulatory T cell epitopes, and optimizing antigens for immunogenicity and protection against disease. iVAX has been applied to vaccine development programs for emerging infectious diseases, cancer antigens and biodefense targets. Several iVAX vaccine design projects have had success in pre-clinical studies in animal models and are progressing toward clinical studies. The toolkit now incorporates a range of immunoinformatics tools for infectious disease and cancer immunotherapy vaccine design. This article will provide a guide to the iVAX approach to computational vaccinology.

Most vaccines require adjuvants for antigen stabilization and immune potentiation. Aluminum-based adjuvants are the most widely used adjuvants for human vaccines. Previous reports demonstrated the preservation of antigen conformation and other antigen characteristics after recovery from adjuvanted Hepatitis B and human papillomavirus vaccines. In this study, we used a combination of various physiochemical and immunochemical methods to analyze hepatitis E vaccine antigen quality attributes after recovery from adjuvants. All biochemical and biophysical methods showed similar characteristics of the p239 protein after recovery from adjuvanted vaccine formulation compared to the antigen in solution which never experienced adsorption/desorption process. Most importantly, we demonstrated full preservation of key antigen epitopes post-recovery from adjuvanted vaccine using a panel of murine monoclonal antibodies as exquisite probes. Antigenicity of p239 was probed with a panel of 9 mAbs using competition/blocking ELISA, surface plasmon resonance and sandwich ELISA methods. These multifaceted analyses demonstrated the preservation of antigen key epitopes and comparable protein thermal stability when adsorbed on adjuvants or of the recovered antigen post-dissolution treatment. A better understanding of the antigen conformation in adjuvanted vaccine will enhanced our knowledge of antigen-adjuvant interactions and facilitate an improved process control and development of stable vaccine formulation.

Cross-reactive peptides on HIV-1 and FIV p24 protein sequences were studied using peripheral blood mononuclear cells (PBMC) from untreated HIV-1-infected long-term survivors (LTS; >10 y of infection without antiretroviral therapy, ART), short-term HIV-1 infected subjects not on ART, and ART-treated HIV-1 infected subjects. IFNγ-ELISpot and CFSE-proliferation analyses were performed with PBMC using overlapping HIV-1 and FIV p24 peptides. Over half of the HIV-1 infected subjects tested (22/31 or 71%) responded to one or more FIV p24 peptide pools by either IFNγ or T-cell proliferation analysis. PBMC and T cells from infected subjects in all 3 HIV(+) groups predominantly recognized one FIV p24 peptide pool (Fp14) by IFNγ production and one additional FIV p24 peptide pool (Fp9) by T-cell proliferation analysis. Furthermore, evaluation of overlapping SIV p24 peptide sequences identified conserved epitope(s) on the Fp14/Hp15-counterpart of SIV, Sp14, but none on Fp9-counterpart of SIV, Sp9. The responses to these FIV peptide pools were highly reproducible and persisted throughout 2-4 y of monitoring. Intracellular staining analysis for cytotoxins and phenotyping for CD107a determined that peptide epitopes from Fp9 and Fp14 pools induced cytotoxic T lymphocyte-associated molecules including perforin, granzyme B, granzyme A, and/or expression of CD107a. Selected FIV and corresponding SIV epitopes recognized by HIV-1 infected patients indicate that these protein sequences are evolutionarily conserved on both SIV and HIV-1 (e.g., Hp15:Fp14:Sp14). These studies demonstrate that comparative immunogenicity analysis of HIV-1, FIV, and SIV can identify evolutionarily-conserved T cell-associated lentiviral epitopes, which could be used as a vaccine for prophylaxis or immunotherapy.

The development of an HIV-1 vaccine that is capable of inducing effective and broadly cross-reactive humoral and cellular immune responses remains a challenging task because of the extensive diversity of HIV-1, the difference of virus subtypes (clades) in different geographical regions, and the polymorphism of human leukocyte antigens (HLA). We performed an in silico design of 3 DNA vaccines, designated pJW4303-MEG1, pJW4303-MEG2 and pJW4303-MEG3, encoding multi-epitopes that are highly conserved within the HIV-1 subtypes most prevalent in China and can be recognized through HLA alleles dominant in China. The pJW4303-MEG1-encoded protein consisted of one Th epitope in Env, and one, 2, and 6 epitopes in Pol, Env, and Gag proteins, respectively, with a GGGS linker sequence between epitopes. The pJW4303-MEG2-encoded protein contained similar epitopes in a different order, but with the same linker as pJW4303-MEG1. The pJW4303-MEG3-encoded protein contained the same epitopes in the same order as that of pJW4303-MEG2, but with a different linker sequence (AAY). To evaluate immunogenicity, mice were immunized intramuscularly with these DNA vaccines. Both pJW4303-MEG1 and pJW4303-MEG2 vaccines induced equally potent humoral and cellular immune responses in the vaccinated mice, while pJW4303-MEG3 did not induce immune responses. These results indicate that both epitope and linker sequences are important in designing effective epitope-based vaccines against HIV-1 and other viruses.

Vaccination is an effective mean of preventing infectious diseases, including those caused by Helicobacter pylori. Th17 cell responses are critical for the pathogenesis of Helicobacter pylori infection. In view of Th17 responses to multi-epitope vaccine CTB-UE, the IL-17 production in antiserum was examined. CTB-UE immunization decreased IL-17 production, implying that Th17 responses may be inhibited. Furthermore, IL-17 aggravated GES-1 cell injury induced by H. pylori SS1; In contrast, CTB-UE antiserum could alleviate this cell injury, which suggesting that CTB-UE can protect GES-1 cell infected with H. pylori SS1 by inhibiting Th17 responses. Treatment of mice with CTB-UE significantly reduced the H. pylori burden and inflammation in the stomach. On the other hand, the production of IL-17 in the stomach in H. pylori-infected mice was increased; but the production of IL-17 in the stomach was decreased after treatment with CTB-UE. Furthermore, the expression of microRNA-155 in gastric tissue was significantly up-regulated. The results suggested that CTB-UE could relieve the H. pylori-induced gastric inflammatory reaction via up-regulating microRNA-155 to inhibit Th17 responses, implying that the microRNA-155/IL-17 pathway was involved. Further study is required to elucidate the relationship between miRNA-155 and IL-17. We found that the production of IL-17 was significantly increased after the expression of miRNA-155 being down-regulated; however, the production of IL-17 was significantly decreased after the expression of miRNA-155 being upregulated.

Prophylactic vaccines against hepatitis B Virus (HBV) infection were produced in different expression systems under different processing conditions. Since the recombinant HBV surface antigen (HBsAg) in these vaccines is a cysteine-rich protein with 14 cysteines among a total of 226 amino acids, the epitopes are dependent on the formation of intra- and intermolecular disulfide bonds. A panel of 22 monoclonal antibodies (mAbs) were developed and evaluated with respect to their sensitivity to disulfide reduction treatment of recombinant HBsAg. Not surprisingly, different mAbs showed different degree of sensitivity to controlled HBsAg disulfide reduction. With a view to exploring the functionality of anti-HBsAg mAbs to be used in HBsAg quality analysis, in vitro neutralization activity for the mAbs was assessed. One of the mAbs tested, 5F11, which showed high sensitivity to the disulfide integrity in HBsAg, was shown also to be highly effective in neutralizing HBV in vitro. Conversely, 42B6, while exhibiting similar neutralization activity, showed comparable binding HBsAg with or without reduction treatment. Based on these mAb characteristics, a sandwich ELISA with 42B6 being the capture Ab and detection Ab was developed to quantify HBsAg (like a “mass” assay) during antigen bioprocessing or in vaccine products. In parallel, when 5F11 was used as the detection Ab (with the same capture Ab), the assay can be used to probe disulfide-dependent and virion-like epitopes in intermediates or final products of hepatitis B vaccine, serving as a surrogate marker for vaccine efficacy to elicit neutralizing antibodies. This approach enables the comparative epitope specific antigenicity analysis of HBsAg antigen preparations from different sources.

Recent studies have suggested that a successful subunit human cytomegalovirus (CMV) vaccine requires improved formulation to generate broad-based anti-viral immunity following immunization. Here we report the development of a non-live protein-based vaccine strategy for CMV based on a polyepitope protein and CMV glycoprotein B (gB) adjuvanted with TLR4 and/or TLR9 agonists. The polyepitope protein includes contiguous multiple MHC class I-restricted epitopes with an aim to induce CD8(+) T cell immunity, while gB is an important target for CD4(+) T cell immunity and neutralizing antibodies. Optimal immunogenicity of this bivalent non-live protein vaccine formulation was dependent upon the co-administration of both the TLR4 and TLR9 agonist, which was associated with the activation of innate immune signatures and the influx of different DC subsets including plasmacytoid DCs and migratory CD8-DEC205+CD103-CD326- langerin-negative dermal DCs into the draining lymph nodes. Furthermore these professional antigen presenting cells also expressed IL-6, IL-12p70, TNFα, and IFNα which play a crucial role in the activation of adaptive immunity. In summary, this study provides a novel platform technology in which broad-based anti-CMV immune responses upon vaccination can be maximised by co-delivery of viral antigens and TLR4 and 9 agonists which induce activation of innate immune signatures and promote potent antigen acquisition and cross-presentation by multiple DC subsets.

Pandemic influenza A(H1N1)pdm09 virus is a global health threat and between 2009–2011 it became the predominant influenza virus subtype circulating in the world. The research describes the MSSCP (Multitemperature Single Strand Conformation Polymorphism) analysis of the hemagglutinin (HA) region encompassing major neutralizing epitope in pandemic influenza isolates from Taiwan. Several genetically distinct changes appeared in isolates obtained in 2010 and 2011. The majority of changes in HA protein did not result in significant modifications, however three modifications were localized in epitope E of H1 and one was part of the interface binding antibodies BH151 and HC45 possibly making the current vaccine less effective.-Taking into account the possibility of the emergence of influenza A with antibody evading potential, the MSSCP method provides an alternative approach for detection of minor variants which escape detection by conventional Sanger sequencing.

An outer membrane protein (OMP) of nontypeable Haemophilus influenzae (NTHi), P6, is a vaccine candidate because it has been characterized as conserved among all H. influenzae strains. Among 151 isolates from children, age 6 to 30 months, evaluating NTHi nasopharyngeal (NP) and oropharyngeal (OP) colonization and tympanocentesis confirmed acute otitis media we identified 14 strains (9.3%) that had variant protein sequences of P6. One atypical omp P6 isolate had sequence mutations in the binding site of a proposed major antigenic epitope of omp P6 identified by monoclonal antibody 7F3. Eight strains (5.3%) had non-homologous variations in amino acids that could result in significant changes to the protein structure of P6, and 5 other strains had amino acid substitutions at four previously described key residue sites. These results show that NTHi omp P6 is not invariant in its structure among respiratory isolates from children.

Approximately 50% of asthma exacerbations and a third of COPD exacerbations are associated with an eosinophilic bronchitis. Quantitative cell counts reliably identify the number of eosinophils in sputum and treatment strategies that are guided by sputum eosinophil counts lead to significantly better outcomes than strategies guided by conventional assessments of symptoms and airflow. However, cell counts are not widely available and the results are not available in real time. Similarly, more sophisticated detection methods using immunoassays or genetic analysis via polymerase chain reaction are too costly and thus not amenable to rapid point-of-care diagnosis. Blood eosinophil counts and fraction of exhaled nitric oxide correlate poorly with airway eosinophilia, particularly in patients with severe airway diseases who are on corticosteroid therapy. Point of care assessments of eosinophil-specific activity may be provided by breathomics that employ metabolomics profiling of volatile compounds in breath. However, it is too early to decide if this would provide quantitative data to monitor therapy and disease activities longitudinally. Herein we provide a perspective on the potential for developing simple point-of-care tests with special emphasis on the potential for a bio-active paper diagnostic test to quantitatively assay the amount of eosinophil peroxidase in sputum samples by employing different types of detection systems.

Targeting of antigens to antigen presenting cells (APC) results in enhanced antigen presentation and T cell activation. In this paper, we describe a novel targeting reagent denoted "Troy-bodies", namely recombinant antibodies with APC-specific V regions and C regions with integrated T cell epitopes. We have made such antibodies with V regions specific for either IgD or MHC class II, and four different T cell epitopes have been tested. All four epitopes could be introduced into loops of C domains without disrupting Ig folding, and they could be released and presented by APC. Furthermore, whether IgD- or MHC-specific, the molecules enhanced T cell stimulation compared to non-specific control antibodies in vitro as well as in vivo. Using this technology, specific reagents can be designed that target selected antigenic peptides to an APC of choice. Troy-bodies may therefore be useful for manipulation of immune responses, and in particular for vaccination purposes.

Interleukin-6 (IL-6) mediates its activity through binding to two cell-surface receptors. The high-affinity human IL-6 receptor complex consists of two transmembrane anchored subunits: a ligand-specific, low-affinity IL-6 receptor and the high-affinity converter and signal transducing, gp130. Previously, using recombinant forms of human IL-6 and the extracellular ('soluble') domains of the IL-6 receptor (sIL-6R) and gp130 (sgp130), we have shown that the high-affinity IL-6R complex is hexameric, consisting of two molecules each of IL-6, sIL-6R and sgp130 (Ward et al., 1994, J. Biol. Chem. 269: 23286-23289). This paper investigates the role of the N-terminal region of gp130 in the formation of the high-affinity IL-6R complex. Using recombinant sgp130 produced with a FLAG octapeptide epitope (DYKDDDDK) at the N-terminus (sgp130-FLAG), we demonstrate, using biosensor analysis and size-exclusion chromatography, that modification of the N-terminus of sgp130 interferes with the in vitro in solution formation of the stable hexameric IL-6 receptor complex. Rather, sgp130-FLAG interacts with IL-6 and sIL-6R with a much lower affinity and forms a stable lower-order ternary complex. However, this lower-order complex is inconsistent with the solution molecular weight of a trimeric complex, as measured by size-exclusion chromatography. In contrast, N-terminal modification of the sgp130 with the FLAG epitope did not interfere with the binding of leukemia inhibitory factor or oncostatin-M (other cytokines that signal through gp130) to sgp130. These data support our model of the hexameric IL-6 receptor complex, which is biased towards the association of two IL-6.IL-6R.gp130 trimers, and postulates the critical involvement of the N-terminal Ig-like domain of gp130 in tethering the two trimers to form the stable hexamer (Simpson et al., 1997, Prot. Sci. 6: 929-955).

This paper describes the idiotypic specificities of eight murine monoclonal antibodies directed to three independent epitopes on retinal S-antigen. The antigenic sites recognised by these monoclonal antibodies have previously been localised to a small region near the C-terminal of bovine S-antigen. Xenogeneic, site-related anti-idiotypes prepared against each of the monoclonal antibodies recognised common idiotypes only amongst those monoclonal antibodies which reacted with the same epitope on S-antigen. Two of the three idiotypes were detected in the sera of BALB/c mice but not in two strains of rat immunised with xenogeneic S-antigen and none could be detected in the sera of patients with anti-photoreceptor autoantibodies. Our results demonstrate that the idiotypes of murine monoclonal antibodies to retinal S-antigen exhibit restricted epitope specificity but are species-restricted and imply that the S-antigen lacks a dominant antigenic epitope.

Polyclonal immune monkey serum raised against schizonts of Plasmodium knowlesi (H-strain) showed the presence of antibodies to lactate dehydrogenase (LDH) of P. knowlesi by immunodot enzyme staining method. The anti-LDH antibodies are most probably directed towards an epitope distinct from the catalytic site as shown by the specific enzyme staining of LDH after binding with antibody on nitrocellulose paper. These antibodies showed reactivity with LDH from different strains (H, P and W1 strains of P. knowlesi) and species (P. cynomolgi B, P. berghei, P. yoelii, P. falciparum and P. vivax) of malarial parasites but did not cross-react with three isoenzymic forms of mammalian LDH (A4, B4 and C4) as well as with LDH from some protozoan and helminth parasites. These findings suggest that the anti-LDH antibodies have defined specificity to Plasmodium spp.

Small nuclear ribonucleoprotein complexes are antigens in various autoimmune diseases. The serological pattern of high titers of circulating antibody to nuclear ribonucleoprotein (RNP) antigen is a diagnostic marker for mixed connective tissue disease (MCTD); whereas antibody to Sm is prevalent in systemic lupus erythematosus (SLE). Both calf thymus and rabbit thymus are commonly used, excellent sources for preparation of the corresponding antigens RNP and Sm in clinical and research laboratories (A. M. Boak et al., accompanying paper). Thus, biochemical and structural characterization of the minimal antigenic determinant in these preparations is important for its use in the laboratory, as well as significant for understanding MCTD, SLE, and other examples of autoimmunity. Purification and biochemical analyses of immunologically active RNP from many different preparations of calf thymus extract has revealed that the majority of antibody in monospecific MCTD patient sera recognizes an antigen composed of the 165 nucleotide RNA, U1 RNA, and five peptides. Calf thymus U1 RNA was found to be identical in sequence to that of man. A sequence of 55 nucleotides within the 165 nucleotide RNA was the minimal RNA fragment found in RNP particles that were still immunologically active. Two of the RNP peptides react with patient sera monospecific for RNP and thus, are presumably the antigenic peptides complexed with the 55 nucleotide RNA sequence.

In this editorial that was published in Immunological Communications, Special Issue on Immunohematology, volume 9, number 2, 1980, the authors unintentionally overlooked an important paper, which provides strong independent support for the interpretation of a structural, hence, qualitative, difference between subgroups A1 and A2. It is as follows