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The generation of an HIV-1 vaccine able to induce long-lasting protective immunity remains a main challenge. Here, we aimed to modify next-generation soluble, prefusion-stabilized, close-to-native, glycan-engineered clade C gp140 envelope (Env) trimers (sC23v4 KIKO and ConCv5 KIKO) for optimal display on the cell surface following homologous or heterologous vector delivery. A combination of the following modifications scored best regarding the preservation of closed, native-like Env trimer conformation and antigenicity when using a panel of selected broadly neutralizing (bnAb) and non-neutralizing (nnAb) monoclonal antibodies for flow cytometry: i) replacing the natural cleavage site with a native flexible linker and introducing a single amino acid substitution to prevent CD4 binding (*), ii) fusing a heterologous VSV-G-derived transmembrane moiety to the gp140 C-terminus, and iii) deleting six residues proximal to the membrane. When delivering membrane-tethered sC23v4 KIKO* and ConCv5 KIKO* via DNA, VSV-GP, and NYVAC vectors, the two native-like Env trimers provide differential antigenicity profiles. Whereas such patterns were largely consistent among the different vectors for either Env trimer, the membrane-tethered ConCv5 KIKO* trimer adopted a more closed and native-like structure than sC23v4 KIKO*. In immunized mice, VSV-GP and NYVAC vectors expressing the membrane-tethered ConCv5 KIKO* administered in prime/boost combination were the most effective regimens for the priming of Env-specific CD4 T cells among all tested combinations. The subsequent booster administration of trimeric ConCv5 KIKO* Env protein preserved the T cell activation levels between groups. The evaluation of the HIV-1-specific humoral responses induced in the different immunization groups after protein boosts showed that the various prime/boost protocols elicited broad and potent antibody responses, preferentially of a Th1-associated IgG2a subclass, and that the obtained antibody levels remained high at the memory phase. In summary, we provide a feasible strategy to display multiple copies of native-like Env trimers on the cell surface, which translates into efficient priming of sustained CD4 T cell responses after vector delivery as well as broad, potent, and sustained antibody responses following booster immunizations with the homologous, prefusion-stabilized, close-to-native ConCv5 KIKO* gp140 Env trimer.

Developing an effective human immunodeficiency virus (HIV) vaccine remains challenging due to difficulties to induce antibodies that neutralize the wide range of HIV-variants. Native-like HIV envelope (Env) trimers in a closed conformation represent promising immunogens. We evaluated the immunogenicity of the chimeric vesicular stomatitis virus-based vector VSV-GP encoding clade C membrane-tethered native-like trimers in heterologous prime/boost combinations with autologous protein. Infected cells displayed high levels of native-like trimers on the surface in a favorable conformation and native-like trimers were also efficiently incorporated into VSV-GP particles. Heterologous vector/protein immunizations outperformed homologous vector regimens, regardless of administration order. In rabbits, these regimens elicited Tier 1 and autologous Tier 2 neutralizing antibodies. Tier 2 neutralization was restricted to pseudoviruses matching the engineered Env-immunogen, with no cross-neutralization of parental Env-variants. Our findings support the use of VSV-GP as a potent platform for displaying native-like Env-trimers and highlight its potential in prime-boost strategies for HIV vaccine development.

The delivery of HIV-1 envelope (Env) trimer-based immunogens on the surface of nanoparticles holds promise to promote immunogenicity with the aim of inducing a potent, durable and broad neutralizing antibody (bnAb) response. Towards that goal, we examined the covalent conjugation of Env to 100 nm and 200 nm silica nanoparticles (SiNPs) to optimize conjugation density and attachment stability. Env was redesigned to enable site-specific cysteine-mediated covalent conjugation while maintaining its structural integrity and antigenicity. Env was anchored to different sized SiNPs with a calculated spacing of 15 nm between adjacent trimers. Both particle sizes exhibited high in vitro stability over a seven-day period. After attachment, 100 nm particles showed better colloidal stability compared to 200 nm particles. Importantly, the antigenic profile of Env was not impaired by surface attachment, indicating that the quaternary structure was maintained. In vitro Env uptake by dendritic cells was significantly enhanced when Env was delivered on the surface of nanoparticles compared to soluble Env. Furthermore, multivalent Env displayed efficiently activated B cells even at Env concentrations in the low nanomolar range. In mice, antibody responses to nanoparticle-coupled Env were stronger compared to the free protein and had equivalent effects at lower doses and without adjuvant.

Stabilization of the HIV-1 Envelope glycoprotein trimer (Env) in its native pre-fusion closed conformation is regarded as one of several requirements for the induction of neutralizing antibody (nAb) responses, which, in turn, will most likely be a prerequisite for the development of an efficacious preventive vaccine. Here, we systematically analyzed how the stepwise stabilization of a clade C consensus (ConC) Env immunogen impacts biochemical and biophysical protein traits such as antigenicity, thermal stability, structural integrity, and particle size distribution. The increasing degree of conformational rigidification positively correlates with favorable protein characteristics, leading to optimized homogeneity of the protein preparations, increased thermal stability, and an overall favorable binding profile of structure-dependent broadly neutralizing antibodies (bnAbs) and non-neutralizing antibodies (non-nAbs). We confirmed that increasing the structural integrity and stability of the Env trimers positively correlates with the quality of induced antibody responses by the immunogens. These and other data contribute to the selection of ConCv5 KIKO as novel Env immunogens for use within the European Union’s H2020 Research Consortium EHVA (European HIV Alliance) for further preclinical analysis and phase 1 clinical development.

Epidermal keratinocytes are enriched with at least nine connexins that are key regulators of epidermal homeostasis. The role of Cx30.3 in keratinocytes and epidermal health became evident when fourteen autosomal dominant mutations in the Cx30.3-encoding GJB4 gene were linked to a rare and incurable skin disorder called erythrokeratodermia variabilis et progressiva (EKVP). While these variants are linked to EKVP, they remain largely uncharacterized hindering therapeutic options. In this study, we characterize the expression and functional status of three EKVP-linked Cx30.3 mutants (G12D, T85P, and F189Y) in tissue-relevant and differentiation-competent rat epidermal keratinocytes. We found that GFP-tagged Cx30.3 mutants were non-functional likely due to their impaired trafficking and primary entrapment within the endoplasmic reticulum (ER). However, all mutants failed to increase BiP/GRP78 levels suggesting they were not inducing an unfolded protein response. FLAG-tagged Cx30.3 mutants were also trafficking impaired yet occasionally exhibited some capacity to assemble into gap junctions. The pathological impact of these mutants may extend beyond their trafficking deficiencies as keratinocytes expressing FLAG-tagged Cx30.3 mutants exhibited increased propidium iodide uptake in the absence of divalent cations. Attempts to rescue the delivery of trafficking impaired GFP-tagged Cx30.3 mutants into gap junctions by chemical chaperone treatment were ineffective. However, co-expression of wild type Cx30.3 greatly enhanced the assembly of Cx30.3 mutants into gap junctions, although endogenous levels of Cx30.3 do not appear to prevent the skin pathology found in patients harboring these autosomal dominant mutations. In addition, a spectrum of connexin isoforms (Cx26, Cx30, and Cx43) exhibited the differential ability to trans-dominantly rescue the assembly of GFP-tagged Cx30.3 mutants into gap junctions suggesting a broad range of connexins found in keratinocytes may favourably interact with Cx30.3 mutants. We conclude that selective upregulation of compatible wild type connexins in keratinocytes may have potential therapeutic value in rescuing epidermal defects invoked by Cx30.3 EKVP-linked mutants.

Understanding the balance between epitope shielding and accessibility on HIV-1 envelope (Env) trimers is essential to guide immunogen selection for broadly neutralizing antibody (bnAb) based vaccines. To investigate the antigenic space of Env immunogens, we created a strategy based on synthetic, high diversity, Designed Ankyrin Repeat Protein (DARPin) libraries. We show that DARPin Antigenicity Analysis (DANA), a purely in vitro screening tool, has the capability to extrapolate relevant information of antigenic properties of Env immunogens. DANA screens of stabilized, soluble Env trimers revealed that stronger trimer stabilization led to the selection of highly mutated DARPins with length variations and framework mutations mirroring observations made for bnAbs. By mimicking heterotypic prime-boost immunization regimens, DANA may be used to select immunogen combinations that favor the selection of trimer-reactive binders. This positions DANA as a versatile strategy for distilling fundamental antigenic features of immunogens, complementary to preclinical immunogenicity testing.

Inflammation is thought to have evolved as a means of reestablishing homeostasis, and thus is closely tied to many physiological and pathological processes. From the perspective of metazoan phylogenetics, granulocyte-lineage cells are relatively ancient and ubiquitous inflammatory mediators. Named for their conspicuous granules, these innate immune cells have historically been studied for their antimicrobial roles, primarily in higher vertebrates. Only recently though, has remarkable diversity of granulocyte form and function across and within species been illuminated. Discoveries of granulocyte subtypes and polarization states have ushered significant interest in and appreciation for these cell types, which are now known to participate in biological processes as varied as reproduction, metabolism, and development. Many features of the classical granulocyte subtypes (neutrophils, eosinophils, basophils, and mast cells) are conserved across distantly related vertebrate species. But each vertebrate class - each species - is subject to disparate selective pressures that presumably shaped the many differences which also exist within this cell lineage. Amphibians, facing distinct biotic and abiotic factors, certainly have granulocyte populations to meet the challenges imposed by those pressures. Yet almost the entirety of existing amphibian granulocyte literature is limited to superficial descriptions of cells morphologically resembling mammalian granulocytes. The current information gap, although daunting, is a source of grand scientific adventures. In this dissertation, I chronicle my own scientific adventures. I present the work of my collaborators and myself, designed to expand our knowledge of amphibian granulocyte biology. Toward this end, we studied this cell lineage in the African clawed frog Xenopus laevis through a series of comprehensive approaches. This anuran has served as a lucrative research tool, particularly for comparative immunologists, for over a century, offering biological insight where newer model organisms are inadequate. In the first part of this thesis, we explore the fundamental immune roles of several X. laevis granulocyte subtypes during host responses to key emerging amphibian pathogens. The experiments described in the second part of this thesis explore X. laevis granulocytes beyond canonical immunity. We instead shift our attention to their participation in non-pathological tissue remodeling, focusing on tail regression during metamorphosis. Altogether, this work unveils a great deal about amphibian granulocyte biology, but also represents just a modest start to fully understanding the variations of the cells that so elegantly meet species-specific needs. Indeed, “every living thing is a masterpiece, written by nature and edited by evolution.”

Carbohydrates are a class of molecule occurring widely in the body. Their presence has varied biological implications, generating clinical interest regarding their impact on disease prognosis. This thesis will investigate the development of chemical entities surrounding two carbohydrates, hyaluronan and inulin. The Receptor for hyaluronan mediated motility (RHAMM) is one of several receptors for hyaluronan (HA), a polysaccharide that, when fragmented, has pro-angiogenic and inflammatory properties. RHAMM expression is tightly regulated during homeostasis but increases in response to cellular stress, including during injury or disease states. HA-RHAMM interactions stimulate the Ras-ERK-Mek pathway to promote cell motility, differentiation, and proliferation. Specific inhibition of HA-RHAMM interactions could have significant therapeutic potential. Chapters 2 and 3 explore two platforms for disrupting HA-RHAMM interactions. Chapter 2 discusses development of a 62-amino acid chemically synthesized truncated RHAMM protein, 7 kDa RHAMM, for use in screening novel therapeutics. This mini-protein exhibited similar secondary structure, bioactivity, and HA-binding capabilities as the full-length protein, and binds known RHAMM-binding peptides with similar affinities as recombinant RHAMM. This suggests that it is a suitable replacement for the difficult-to-obtain recombinant version. Chapter 3 discusses the development of double stapled RHAMM peptide mimetics as therapeutic anti-inflammatory agents. The peptides were evaluated for secondary structure, HA-binding capability, and inflammation-related bioactivity. The lead compound blocked 27.2% and 52% of induced inflammation in culture and in vivo, respectively. The lead peptide was further optimized to improve metabolic stability while maintaining secondary structure and HA-binding affinity, improving therapeutic efficacy. Glomerular filtration rate (GFR) is a measure of kidney function and a prognostic indicator of chronic kidney disease. Filtration of the polysaccharide inulin is the gold standard for measuring GFR clinically, as it is neither reabsorbed nor secreted by the kidneys; however, this method is laborious and invasive. Chapter 3 explores the development of a near-infrared dye-labeled inulin, Cy7.5-inulin conjugate, as an optical probe to accurately and non-invasively measure GFR by transcutaneous pulse dye densitometer. The conjugate was characterized by different analytical techniques, and is stable under in vivo conditions. The probe was successfully used in a pig model to accurately measure GFR non-invasively.

In two identical trials involving a total of 1882 patients with multiple sclerosis, the human anti-CD20 monoclonal antibody ofatumumab was associated with a lower annualized relapse rate than the pyrimidine-synthesis inhibitor teriflunomide, as well as fewer lesions on MRI.

A characteristic of adaptive behavior is its goal-directed nature. An ability to act in a goal-directed manner is progressively refined during development, but this refinement can be impacted by the emergence of psychiatric disorders. Disorders of compulsivity have been framed computationally as a deficit in model-based control, and have been linked also to abnormal frontostriatal connectivity. However, the developmental trajectory of model-based control, including an interplay between its maturation and an emergence of compulsivity, has not been characterized. Availing of a large sample of healthy adolescents (n = 569) aged 14 to 24 y, we show behaviorally that over the course of adolescence there is a withinperson increase in model-based control, and this is more pronounced in younger participants. Using a bivariate latent change score model, we provide evidence that the presence of higher compulsivity traits is associated with an atypical profile of this developmental maturation in model-based control. Resting-state fMRI data from a subset of the behaviorally assessed subjects (n = 230) revealed that compulsivity is associated with a less pronounced change of within-subject developmental remodeling of functional connectivity, specifically between the striatum and a frontoparietal network. Thus, in an otherwise clinically healthy population sample, in early development, individual differences in compulsivity are linked to the developmental trajectory of model-based control and a remodeling of frontostriatal connectivity.