Virus-like particle vaccinology, from bench to bedside.

Virus-like particles (VLPs) have become key tools in biology, medicine and even engineering. After their initial use to resolve viral structures at the atomic level, VLPs were rapidly harnessed to develop antiviral vaccines followed by their use as display platforms to generate any kind of vaccine. Most recently, VLPs have been employed as nanomachines to deliver pharmaceutically active products to specific sites and into specific cells in the body. Here, we focus on the use of VLPs for the development of vaccines with broad fields of indications ranging from classical vaccines against viruses to therapeutic vaccines against chronic inflammation, pain, allergy and cancer. In this review, we take a walk through time, starting with the latest developments in experimental preclinical VLP-based vaccines and ending with marketed vaccines, which earn billions of dollars every year, paving the way for the next wave of prophylactic and therapeutic vaccines already visible on the horizon

Understanding wildlife exploitation and ways forward on different scales

Der Rückgang der Wildtiere kann Ökosysteme tiefgreifend verändern und das Risiko von Ernährungsunsicherheit und neu auftretenden Krankheiten erhöhen, die wiederum die globale Gesundheit, Gesellschaft und Wirtschaft bedrohen. Aufbauend auf dem theoretischen Überbau des Konzepts komplexer sozial-ökologischer Systeme untersuche ich in dieser Dissertation die Jagd und den Wildtierhandel in einem ganzheitlichen, differenzierten und skalensensitiven Ansatz. Dabei untersuche ich die Ursachen der Wildtiernutzung auf verschiedenen Ebenen (z.B. Nutzergruppen) und Skalen (lokal, global). Ich untersuchte ein lokales Umfeld durch eine Fallstudie um den Taï-Nationalpark in der Elfenbeinküste, indem ich 348 Jäger, 202 Buschfleischhändler, 190 Restaurantbesitzer und 985 Verbraucher in 47 städtischen und ländlichen Siedlungen befragte. Darüber hinaus untersuchte ich mithilfe von 114 persönlichen Interviews mit Nationalparkdirektoren in 25 afrikanischen und europäischen Ländern die Ausprägung der Jagd über den sozioökonomisch und ökologisch kontrastreichen globalen Süd-Nord-Gradienten. Die lokale Fallstudie zeigte die Heterogenität der Wildfleisch-Warenkette, in der mehrere Akteure Wildfleisch und verschiedene Taxa aus unterschiedlichen wirtschaftlichen, kulturellen oder ernährungsbedingten Beweggründen nutzen. Die globale Perspektive zeigte die sich verändernden Erscheinungsformen und Gründe für die Jagd entlang des globalen Süd-Nord-Gradienten. Im Süden überwog die illegale und kommerzielle Jagd auf Pflanzenfresser, während im Norden die legale, kulturell und sozial motivierte Jagd auf Huftiere und die illegale Jagd auf Raubtiere außerhalb von Parkgrenzen dominierte. Die Einbindung lokaler Gemeinschaften und die Berücksichtigung universeller Mechanismen menschlicher Kooperation könnte dem Naturschutz und der sozialen Gerechtigkeit zugutekommen. Nichtsdestotrotz verdeutlichen die Auswirkungen großräumiger Faktoren auf lokale Systeme die Notwendigkeit, gut umgesetzte lokale Maßnahmen mit einer angemessenen globalen Governance zu kombinieren, um den Raubbau an der Natur einzudämmen.Declining wildlife can profoundly alter ecosystems and increase the risks of food insecurity and emerging diseases that threaten global health, societies, and economies. Building on the theoretical superstructure of complex social-ecological systems, I examine wildlife trade in a holistic, differentiated, and scale-sensitive approach, exploring the causes of wildlife use at different levels (e.g. user groups) and scales (local, global). I examined a local setting through a case study around Taï National Park in Côte d'Ivoire by interviewing 348 hunters, 202 bushmeat traders, 190 restaurant owners, and 985 consumers in 47 urban and rural settlements. Furthermore, I investigated the manifestation of hunting across the Global South-North gradient through 114 face-to-face interviews with national park directors in 25 African and European countries. The local case study revealed the heterogeneity of the wild meat commodity chain, in which multiple actors use wild meat and different taxa for varying economic, cultural, or nutritional motivations. The global perspective revealed the shifting manifestations and reasons for hunting along the Global South-North gradient. Illegal, commercial hunting of herbivores prevailed in the South, while legal, culturally-, and socially-motivated hunting of ungulates and the illegal pursuit of predators outside park boundaries were common in the North. Engaging local communities and incorporating universal mechanisms of human cooperation into conservation could benefit conservation and social justice. The impacts of large-scale drivers on local systems highlight the need for combining well-implemented local action and appropriate global governance to curb wildlife overexploitatio

Increased receptor affinity of SARS-CoV-2: a new immune escape mechanism.

‘Affinity escape’: Novel SARS-CoV-2 variants may escape immunity by raising the RBD-ACE2 affinity high enough to outcompete the avidity of neutralizing antibodies

Vaccination against Allergy: A Paradigm Shift?

Since the discovery that IgE antibodies mediate allergy, decades of research have unraveled complex mechanisms associated with conventional immunotherapy and the vital protagonists that shape 'immune tolerance' to allergens. Debate exists on what should constitute the dominant effector mechanism in driving rational drug designs for next-generation immunotherapies. As vaccine technology continues to advance, the development of novel vaccines in this area of continued medical need might stand on a threshold of breakthrough inspired by experiments by Dunbar on the passive vaccination of allergic animals more than 100 years ago. In this opinion article, we discuss both novel insights into IgG antibodies as the principle effector modality induced by specific immunotherapy and advances in antigen-carrier design that may catapult allergy treatment into our modern world

Regulation of pulmonary plasma cell responses during secondary infection with influenza virus

During secondary infection with influenza virus, plasma cells (PCs) develop within the lung, providing a local source of antibodies. However, the site and mechanisms that regulate this process are poorly defined. Here, we show that while circulating memory B cells entered the lung during rechallenge and were activated within inducible bronchus-associated lymphoid tissues (iBALTs), resident memory B (BRM) cells responded earlier, and their activation occurred in a different niche: directly near infected alveoli. This process required NK cells but was largely independent of CD4 and CD8 T cells. Innate stimuli induced by virus-like particles containing ssRNA triggered BRM cell differentiation in the absence of cognate antigen, suggesting a low threshold of activation. In contrast, expansion of PCs in iBALTs took longer to develop and was critically dependent on CD4 T cells. Our work demonstrates that spatially distinct mechanisms evolved to support pulmonary secondary PC responses, and it reveals a specialized function for BRM cells as guardians of the alveoli

Induction of Broadly Cross-Reactive Antibodies by Displaying Receptor Binding Domains of SARS-CoV-2 on Virus-like Particles.

The impact of the COVID-19 pandemic has been reduced since the application of vaccination programs, mostly shown in the reduction of hospitalized patients. However, the emerging variants, in particular Omicron, have caused a steep increase in the number of infections; this increase is, nevertheless, not matched by an increase in hospitalization. Therefore, a vaccine that induces cross-reactive antibodies against most or all variants is a potential solution for the issue of emerging new variants. Here, we present a vaccine candidate which displays receptor-binding domain (RBD) of SARS-CoV-2 on virus-like particles (VLP) that, in mice, not only induce strong antibody responses against RBD but also bind RBDs from other variants of concern (VOCs). The antibodies induced by wild-type (wt) RBD displayed on immunologically optimized Cucumber mosaic virus incorporated tetanus toxin (CuMVTT) VLPs bind to wt as well as RBDs of VOCs with high avidities, indicating induction of strongly cross-reactive IgG antibodies. Interestingly, similar cross-reactive IgA antibodies were induced in immunized mice. Furthermore, these cross-reactive antibodies demonstrated efficacy in neutralizing wt (Wuhan) as well as SARS-CoV-2 VOCs (Beta, Delta, and Gamma). In summary, RBDs displayed on VLPs are capable of inducing protective cross-reactive IgG and IgA antibodies in mice, indicating that it may be possible to cover emerging VOCs with a single vaccine based on wt RBD

Molecular definition of severe acute respiratory syndrome coronavirus 2 receptor-binding domain mutations: Receptor affinity versus neutralization of receptor interaction.

BACKGROUND Several new variants of SARS-CoV-2 have emerged since fall 2020 which have multiple mutations in the receptor-binding domain (RBD) of the spike protein. It is unclear which mutations affect receptor affinity versus immune recognition. METHODS We produced wild type RBD, RBD with single mutations (E484K, K417N, or N501Y) or with all three mutations combined and tested their binding to ACE2 by biolayer interferometry (BLI). The ability of convalescent sera to recognize RBDs and block their interaction with ACE2 was tested as well. RESULTS We demonstrated that single mutation N501Y increased binding affinity to ACE2 but did not strongly affect its recognition by convalescent sera. In contrast, single mutation E484K had almost no impact on the binding kinetics, but essentially abolished recognition of RBD by convalescent sera. Interestingly, combining mutations E484K, K417N, and N501Y resulted in a RBD with both features: enhanced receptor binding and abolished immune recognition. CONCLUSIONS Our data demonstrate that single mutations either affect receptor affinity or immune recognition while triple mutant RBDs combine both features

In situ delivery of nanoparticles formulated with micron-sized crystals protects from murine melanoma.

INTRODUCTION Intratumoral injections of novel therapeutics can activate tumor antigen-specific T cells for locoregional tumor control and may even induce durable systemic protection (against distant metastases) via recirculating T cells. Here we explored the possibility of a universal immunotherapy that promotes T-cell responses in situ and beyond, upon intratumoral injection of nanoparticles formulated with micron-sized crystals. METHODS Cucumber mosaic virus-like particles containing a tetanus toxin peptide (CuMVTT) were formulated with microcrystalline tyrosine (MCT) adjuvant and injected directly in B16F10 melanoma tumors. To further enhance immunogenicity, we loaded the nanoparticles with a TLR7/8 ligand and incorporated a universal tetanus toxin T-helper cell peptide. We assessed therapeutic efficacy and induction of local and systemic immune responses, including RNA sequencing, providing broad insight into the tumor microenvironment and correlates of protection. RESULTS MCT crystals were successfully decorated with CuMVTT nanoparticles. This 'immune-enhancer' formed immunogenic depots in injected tumors, enhanced polyfunctional CD8+ and CD4+ T cells, and inhibited B16F10 tumor growth locally and systemically. Local inflammation and immune responses were associated with upregulation of genes involved in complement activation and collagen formation. CONCLUSIONS Our new immune-enhancer turned immunologically cold tumors into hot ones and inhibited local and distant tumor growth. This type of immunotherapy does not require the identification of (patient-individual) relevant tumor antigens. It is well tolerated, non-infectious, and affordable, and can readily be upscaled for future clinical testing and broad application in melanoma and likely other solid tumors

Increased Receptor Affinity and Reduced Recognition by Specific Antibodies Contribute to Immune Escape of SARS-CoV-2 Variant Omicron.

In this report, we mechanistically reveal how the Variant of Concern (VOC) SARS-CoV-2 Omicron (B.1.1.529) escapes neutralizing antibody responses, by physio-chemical characterization of this variant in comparison to the wild-type Wuhan and the Delta variant (B.1.617.2). Convalescent sera, as well as sera obtained from participants who received two or three doses of mRNA vaccines (Moderna-mRNA-1273® or Pfizer-BNT162b2®), were used for comparison in this study. Our data demonstrate that both Delta, as well as Omicron variants, exhibit a higher affinity for the receptor ACE2, facilitating infection and causing antibody escape by receptor affinity (affinity escape), due to the reduced ability of antibodies to compete with RBD-receptor interaction and virus neutralization. In contrast, only Omicron but not the Delta variant escaped antibody recognition, most likely because only Omicron exhibits the mutation at E484A, a position associated with reduced recognition, resulting in further reduced neutralization (specificity escape). Nevertheless, the immunizations with RNA-based vaccines resulted in marked viral neutralization in vitro for all strains, compatible with the fact that Omicron is still largely susceptible to vaccination-induced antibodies, despite affinity- and specificity escape