Rational Design Of Novel Vaccines Research Articles

Atomic structures and deletion mutant reveal different capsid-binding patterns and functional significance of tegument protein pp150 in murine and human cytomegaloviruses with implications for therapeutic development.

Cytomegalovirus (CMV) infection causes birth defects and life-threatening complications in immunosuppressed patients. Lack of vaccine and need for more effective drugs have driven widespread ongoing therapeutic development efforts against human CMV (HCMV), mostly using murine CMV (MCMV) as the model system for preclinical animal tests. The recent publication (Yu et al., 2017, DOI: 10.1126/science.aam6892) of an atomic model for HCMV capsid with associated tegument protein pp150 has infused impetus for rational design of novel vaccines and drugs, but the absence of high-resolution structural data on MCMV remains a significant knowledge gap in such development efforts. Here, by cryoEM with sub-particle reconstruction method, we have obtained the first atomic structure of MCMV capsid with associated pp150. Surprisingly, the capsid-binding patterns of pp150 differ between HCMV and MCMV despite their highly similar capsid structures. In MCMV, pp150 is absent on triplex Tc and exists as a “Λ”-shaped dimer on other triplexes, leading to only 260 groups of two pp150 subunits per capsid in contrast to 320 groups of three pp150 subunits each in a “Δ”-shaped fortifying configuration. Many more amino acids contribute to pp150-pp150 interactions in MCMV than in HCMV, making MCMV pp150 dimer inflexible thus incompatible to instigate triplex Tc-binding as observed in HCMV. While pp150 is essential in HCMV, our pp150-deletion mutant of MCMV remained viable though with attenuated infectivity and exhibiting defects in retaining viral genome. These results thus invalidate targeting pp150, but lend support to targeting capsid proteins, when using MCMV as a model for HCMV pathogenesis and therapeutic studies.

Innate Immunity and Vaccines

The use of vaccines has led to tremendous decreases in disease burdens across the world. Many challenges remain in expanding vaccine coverage to new pathogens, however, a struggle further hampered by a lack of understanding into many of the fundamental processes through which vaccines elicit robust immunity. In this review we cover recent advances in the field of innate immunity and vaccinology that offer new insights into the reasons some vaccines may succeed or fail. We begin with the secreted cytokines that can influence the nature of the adaptive immune response, and how these may be tuned with the use of particular adjuvants. From there we cover dendritic cells, perhaps the key cell at the interface between innate and adaptive immunity. We discuss mechanisms for targeting specific subsets of dendritic cells, and the effects of this targeting. We further discuss additional modifications of the vaccine formulation to enhance interactions with innate immunity, including phagocytocis and antigen presentation. Finally, we step back to review recent advances in systems biology, and the ability of these new tools to provide deeper understanding of innate immune functions. We hope that this review will provide researchers with access to a breadth and depth of recent work that will allow for the rational design of novel vaccines to combat the most serious infectious diseases of today and tomorrow.

Flagellin from Recombinant Attenuated Salmonella enterica Serovar Typhimurium Reveals a Fundamental Role in Chicken Innate Immunity

Recombinant attenuated Salmonella vaccines have been extensively studied, with a focus on eliciting specific immune responses against foreign antigens. However, very little is known about the innate immune responses, particularly the role of flagellin, in the induction of innate immunity triggered by recombinant attenuated Salmonella in chickens. In the present report, we describe two Salmonella enterica serovar Typhimurium vaccine strains, wild-type (WT) or flagellin-deficient (flhD) Salmonella, both expressing the fusion protein (F) gene of Newcastle disease virus. We examined the bacterial load and spatiotemporal kinetics of expression of inflammatory cytokine, chemokine, and Toll-like receptor 5 (TLR5) genes in the cecum, spleen, liver, and heterophils following oral immunization of chickens with the two Salmonella strains. The flhD mutant exhibited an enhanced ability to establish systemic infection compared to the WT. In contrast, the WT strain induced higher levels of interleukin-1β (IL-1β), CXCLi2, and TLR5 mRNAs in cecum, the spleen, and the heterophils than the flhD mutant at different times postinfection. Collectively, the present data reveal a fundamental role of flagellin in the innate immune responses induced by recombinant attenuated Salmonella vaccines in chickens that should be considered for the rational design of novel vaccines for poultry.

A recombinant Bacille Calmette–Guérin construct expressing the Plasmodium falciparum circumsporozoite protein enhances dendritic cell activation and primes for circumsporozoite-specific memory cells in BALB/c mice

A protective malaria vaccine may induce both high levels of neutralising antibodies and strong T-cell responses. The Plasmodium falciparum circumsporozoite protein (CSp) is a leading pre-erythrocytic vaccine candidate. CSp is a week immunogen per se, but Mycobacterium bovis Bacille Calmette–Guérin (BCG) has excellent adjuvant activity and has been utilized as a vector to deliver heterologous vaccine candidate antigens. It is safe in immunocompetent individuals and inexpensive to produce.We assessed in vitro and in vivo a recombinant BCG-expressing CSp (BCG-CS) as malaria vaccine candidate. Immunisation of BALB/c mice with BCG-CS augmented numbers of dendritic cells (DCs) in draining lymph nodes and in the spleen. The activation markers MHC-class-II, CD40, CD80 and CD86 on DCs were significantly upregulated by BCG-CS as compared to wild-type BCG (wt-BCG). In vitro stimulation of bone marrow-derived DCs and macrophages with BCG-CS induced IL-12 and TNF-α production. BCG-CS induced higher phagocytic activity in macrophages as compared to wt-BCG. Immunogenicity studies show that BCG-CS induced CS-specific antibodies and IFN-γ-producing memory cells.In conclusion, BCG-CS is highly efficient in activating antigen-presenting cells (APCs) for priming of adaptive immunity. Implications for the rational design of novel vaccines against malaria and TB, the two major devastating poverty-related diseases, are discussed.

Future Vaccination Strategies against Tuberculosis: Thinking outside the Box

With almost a dozen vaccine candidates in clinical trials, tuberculosis (TB) research and development is finally reaping the first fruits of its labors. Vaccine candidates in clinical trials may prevent TB disease reactivation by efficiently containing the pathogen Mycobacterium tuberculosis (Mtb). Future research should target vaccines that achieve sterile eradication of Mtb or even prevent stable infection. These are ambitious goals that can be reached only by highly cooperative engagement of basic immunologists, vaccinologists, and clinical researchers--or in other words, by translation from basic immunology to vaccine research and development, as well as reverse translation of insights from clinical trials back to hypothesis-driven research in the basic laboratory. Here, we review current and future strategies toward the rational design of novel vaccines against TB, as well as the progress made thus far, and the hurdles that need to be overcome in the near and distant future.

Understanding human myeloid dendritic cell subsets for the rational design of novel vaccines

Dendritic cells (DCs) orchestrate a repertoire of immune responses that endows resistance to infection and tolerance to self. Understanding the principles by which DCs control immunity and tolerance has provided a rich basis for studying and improving clinical outcome of human disease treatment. Several features contribute to the complexity of the DC system. Among these, plasticity and existence of subsets are prominent determinants to the quality of the elicited immune responses. Indeed, different DC subsets are distributed in peripheral tissues and the blood and display different microbial receptors, surface molecules and cytokine expression, all of which influence the immunologic outcome. The biologic raison d'être for separate DC subsets has been the focus of many studies including our own and is being reviewed with an emphasis on human skin DCs.

Automated Detection of Conformational Epitopes Using Phage Display Peptide Sequences

Precise determination of conformational epitopes of neutralizing antibodies represents a key step in the rational design of novel vaccines. A powerful experimental method to gain insights on the physical chemical nature of conformational epitopes is the selection of linear peptides that bind with high affinities to a monoclonal antibody of interest by phage display technology. However, the structural characterization of conformational epitopes from these mimotopes is not straightforward, and in the past the interpretation of peptide sequences from phage display experiments focused on linear sequence analysis to find a consensus sequence or common sequence motifs. We present a fully automated search method, EpiSearch that predicts the possible location of conformational epitopes on the surface of an antigen. The algorithm uses peptide sequences from phage display experiments as input, and ranks all surface exposed patches according to the frequency distribution of similar residues in the peptides and in the patch. We have tested the performance of the EpiSearch algorithm for six experimental data sets of phage display experiments, the human epidermal growth factor receptor-2 (HER-2/neu), the antibody mAb Bo2C11 targeting the C(2) domain of FVIII, antibodies mAb 17b and mAb b12 of the HIV envelope protein gp120, mAb 13b5 targeting HIV-1 capsid protein and 80R of the SARS coronavirus spike protein. In all these examples the conformational epitopes as determined by the X-ray crystal structures of the antibody-antigen complexes, were found within the highest scoring patches of EpiSearch, covering in most cases more than 50% residues of experimental observed conformational epitopes. Input options of the program include mapping of a single peptide or a set of peptides on the antigen structure, and the results of the calculation can be visualized on our interactive web server. Users can access the EpiSearch from our web server http://curie.utmb.edu/episearch.html.

F.140. Understanding Human Myeloid Dendritic Cell Subsets for the Rational Design of Novel Vaccines

F.140. Understanding Human Myeloid Dendritic Cell Subsets for the Rational Design of Novel Vaccines

Action and Reaction: The Arthropod-Borne Flaviviruses and Host Interferon Responses

The arthropod-borne flaviviruses include tick- and mosquito-borne viruses that are causes of globally significant emerging diseases. These single-stranded RNA viruses are exquisitely sensitive to the antiviral effects of host interferons. However, both the tick- and mosquito-borne flaviviruses are capable of modulating the interferon response. Despite the high degree of similarity among members of the flavivirus genus, the mechanisms employed by individual viruses to modulate interferon responses differ. This review considers the arthropod-borne flaviviruses and the host interferon response as a pair of forces, the action and the reaction. The interaction of these two forces has led to a complex relationship between virus and host. An increased understanding of these interactions will likely facilitate the rational design of novel vaccines and therapeutics.

Bacterial proteomics and vaccine development.

Until recently, the development of vaccines for use in humans relied on the response to attenuated or whole-cell preparations, or empirically selected antigens. The post-genomic era holds the possibility of rational design of novel vaccines for important human pathogens. The discovery and development of these new vaccines is likely to be accomplished through integrated proteomic strategies. Although most proteomic studies are based on two-dimensional gel electrophoresis (2D-PAGE) as a separation technique, new methods have been developed within the past two years that provide complementary information concerning microbial protein expression. The 2D-PAGE technique in combination with Western blotting has been successfully applied in the discovery of antigens from Helicobacter pylori, Chlamydia trachomatis and Borrelia garinii. Two-dimensional semi-preparative electrophoresis has provided complementary information regarding membrane protein expression in a strain of H. pylori. Through two-dimensional liquid chromatography-tandem mass spectrometry, the most comprehensive information to date regarding protein expression in yeast was obtained. This technique may shortly become an important tool in vaccinology. This review of the current state of bacterial proteomics as applied in vaccinology presents analytical techniques for protein separation, proteomics without gels, reverse vaccinology, and functional approaches to the identification of virulence proteins in microbes.