mRNA vaccines expressing malaria transmission-blocking antigens Pfs25 and Pfs230D1 induce a functional immune response.

Malaria transmission-blocking vaccines (TBV) are designed to inhibit the sexual stage development of the parasite in the mosquito host and can play a significant role in achieving the goal of malaria elimination. Preclinical and clinical studies using protein-protein conjugates of leading TBV antigens Pfs25 and Pfs230 domain 1 (Pfs230D1) have demonstrated the feasibility of TBV. Nevertheless, other promising vaccine platforms for TBV remain underexplored.

Aotus nancymaae model predicts human immune response to the placental malaria vaccine candidate VAR2CSA.

Placental malaria vaccines (PMVs) are being developed to prevent severe sequelae of placental malaria (PM) in pregnant women and their offspring. The leading candidate vaccine antigen VAR2CSA mediates parasite binding to placental receptor chondroitin sulfate A (CSA). Despite promising results in small animal studies, recent human trials of the first two PMV candidates (PAMVAC and PRIMVAC) generated limited cross-reactivity and cross-inhibitory activity to heterologous parasites.

Protein-protein conjugation enhances the immunogenicity of SARS-CoV-2 receptor-binding domain (RBD) vaccines.

Several effective SARS-CoV-2 vaccines have been developed using different technologies. Although these vaccines target the isolates collected early in the pandemic, many have protected against serious illness from newer variants. Nevertheless, efficacy has diminished against successive variants and the need for effective and affordable vaccines persists especially in the developing world.

Malaria transmission-blocking conjugate vaccine in ALFQ adjuvant induces durable functional immune responses in rhesus macaques.

Malaria transmission-blocking vaccines candidates based on Pfs25 and Pfs230 have advanced to clinical studies. Exoprotein A (EPA) conjugate of Pfs25 in Alhydrogel developed functional immunity in humans, with limited durability. Pfs230 conjugated to EPA (Pfs230D1-EPA) with liposomal adjuvant AS01 is currently in clinical trials in Mali.

Pfs230 yields higher malaria transmission-blocking vaccine activity than Pfs25 in humans but not mice.

BACKGROUNDVaccines that block human-to-mosquito Plasmodium transmission are needed for malaria eradication, and clinical trials have targeted zygote antigen Pfs25 for decades. We reported that a Pfs25 protein-protein conjugate vaccine formulated in alum adjuvant induced serum functional activity in both US and Malian adults. However, antibody levels declined rapidly, and transmission-reducing activity required 4 vaccine doses.

Comparison of carrier proteins to conjugate malaria transmission blocking vaccine antigens, Pfs25 and Pfs230.

Malaria transmission blocking vaccines (TBV) target the sexual stage of the parasite and have been pursued as a stand-alone vaccine or for combination with pre-erythrocytic or blood stage vaccines. Our efforts to develop TBV focus primarily on two antigens, Pfs25 and Pfs230. Chemical conjugation of these poorly immunogenic antigens to carrier proteins enhances their immunogenicity, and conjugates of these antigens to Exoprotein A (EPA) are currently under evaluation in clinical trials.

Outer membrane protein complex as a carrier for malaria transmission blocking antigen Pfs230.

Malaria transmission blocking vaccines (TBV) target the mosquito stage of parasite development by passive immunization of mosquitoes feeding on a vaccinated human. Through uptake of vaccine-induced antibodies in a blood meal, mosquito infection is halted and hence transmission to another human host is blocked. Pfs230 is a gametocyte and gamete surface antigen currently under clinical evaluation as a TBV candidate.

Physical-chemical measurement method development for self-assembled, core-shell nanoparticles.

Improvements in dimensional metrology and innovations in physical-chemical characterization of functionalized nanoparticles are critically important for the realization of enhanced performance and benefits of nanomaterials. Toward this goal, we propose a multi-technique measurement approach, in which correlated atomic force microscopy, dynamic light scattering, high performance liquid chromatography and mass spectroscopy measurements are used to assess molecular and structural properties of self-assembled polyplex nanoparticles with a core-shell structure. In this approach, measurement methods are first validated with a model system consisting of gold nanoparticles functionalized with synthetic polycationic branched polyethylenimine macromolecules.

Development of a bivalent conjugate vaccine candidate against malaria transmission and typhoid fever.

Immune responses to poorly immunogenic antigens, such as polysaccharides, can be enhanced by conjugation to carriers. Our previous studies indicate that conjugation to Vi polysaccharide of Salmonella Typhi may also enhance immunogenicity of some protein carriers. We therefore explored the possibility of generating a bivalent vaccine against Plasmodium falciparum malaria and typhoid fever, which are co-endemic in many parts of the world, by conjugating Vi polysaccharide, an approved antigen in typhoid vaccine, to Pfs25, a malaria transmission blocking vaccine antigen in clinical trials.

Protein-protein conjugate nanoparticles for malaria antigen delivery and enhanced immunogenicity.

Chemical conjugation of polysaccharide to carrier proteins has been a successful strategy to generate potent vaccines against bacterial pathogens. We developed a similar approach for poorly immunogenic malaria protein antigens. Our lead candidates in clinical trials are the malaria transmission blocking vaccine antigens, Pfs25 and Pfs230D1, individually conjugated to the carrier protein Exoprotein A (EPA) through thioether chemistry.

Adjuvant and carrier protein-dependent T-cell priming promotes a robust antibody response against the Plasmodium falciparum Pfs25 vaccine candidate.

Humoral immune responses have the potential to maintain protective antibody levels for years due to the immunoglobulin-secreting activity of long-lived plasma cells (LLPCs). However, many subunit vaccines under development fail to generate robust LLPC responses, and therefore a variety of strategies are being employed to overcome this limitation, including conjugation to carrier proteins and/or formulation with potent adjuvants. Pfs25, an antigen expressed on malaria zygotes and ookinetes, is a leading transmission blocking vaccine (TBV) candidate for Plasmodium falciparum.

Increased tumor distribution and expression of histidine-rich plasmid polyplexes.

Background: Selecting nonviral carriers for in vivo gene delivery is often dependent on determining the optimal carriers from transfection assays in vitro. The rationale behind this in vitro strategy is to cast a net sufficiently wide to identify the few effective carriers of plasmids for in vivo studies. Nevertheless, many effective in vivo carriers may be overlooked by this strategy because of the marked differences between in vitro and in vivo assays.

Systemic miRNA-7 delivery inhibits tumor angiogenesis and growth in murine xenograft glioblastoma.

Tumor-angiogenesis is the multi-factorial process of sprouting of endothelial cells (EC) into micro-vessels to provide tumor cells with nutrients and oxygen. To explore miRNAs as therapeutic angiogenesis-inhibitors, we performed a functional screen to identify miRNAs that are able to decrease EC viability. We identified miRNA-7 (miR-7) as a potent negative regulator of angiogenesis.

Enhancement of antifungal activity by integrin-targeting of branched histidine rich peptides.

The treatment of invasive candidiasis associated with growing numbers of immunocompromised patients remains a major challenge complicated by increasing drug resistance. A novel class of branched histidine-lysine (bHK) peptides has promising antifungal activity, and exhibits a mechanism similar to natural histatins, and thus may avoid drug resistance. The present studies evaluate ligand targeting of bHK peptides to fungal surface integrins by determining whether a cyclic RGD (cRGD) peptide with a large PEG linker could enhance bHK peptide antifungal activity.

Surface-modified HK:siRNA nanoplexes with enhanced pharmacokinetics and tumor growth inhibition.

We characterized in this study the pharmacokinetics and antitumor efficacy of histidine-lysine (HK):siRNA nanoplexes modified with PEG and a cyclic RGD (cRGD) ligand targeting αvβ3 and αvβ5 integrins. With noninvasive imaging, systemically administered surface-modified HK:siRNA nanoplexes showed nearly 4-fold greater blood levels, 40% higher accumulation in tumor tissue, and 60% lower luciferase activity than unmodified HK:siRNA nanoplexes. We then determined whether the surface-modified HK:siRNA nanoplex carrier was more effective in reducing MDA-MB-435 tumor growth with an siRNA targeting Raf-1.

Buffering capacity and size of siRNA polyplexes influence cytokine levels.

Induction of cytokines by small interfering RNA (siRNA) polyplexes has been a significant concern of researchers attempting to minimize the toxicity of this promising therapy. Although cationic carriers of siRNA are known to increase cytokine levels, few systematic studies have been done to determine what properties of the carrier are important to modulate cytokines. Because branched histidine-lysine (HK) peptides are effective carriers of siRNA and their sequence can be readily modified, we selected this class of carrier to determine which sequences of the peptide were important for cytokine induction.

Polyethyleneimine (PEI) mediated siRNA gene silencing in the Schistosoma mansoni snail host, Biomphalaria glabrata.

An in vivo, non-invasive technique for gene silencing by RNA interference (RNAi) in the snail, Biomphalaria glabrata, has been developed using cationic polymer polyethyleneimine (PEI) mediated delivery of long double-stranded (ds) and small interfering (si) RNA. Cellular delivery was evaluated and optimized by using a 'mock' fluorescent siRNA. Subsequently, we used the method to suppress expression of Cathepsin B (CathB) with either the corresponding siRNA or dsRNA of this transcript.

A branched histidine/lysine peptide, H2K4b, in complex with plasmids encoding antitumor proteins inhibits tumor xenografts.

Background: In this study we investigated whether a particular branched HK polymer, H2K4b, was an effective in vivo carrier of plasmids expressing the antiangiogenic kringle 1-5 or the tumor suppressor p53.

Methods: H2K4b was synthesized on a solid-phase peptide synthesizer. Distribution, optimization and time course studies were done in tumor-bearing nude mice by systemically administering H2K4b in complex with a luciferase-expressing plasmid.

Transporting silence: design of carriers for siRNA to angiogenic endothelium.

The recently developed siRNA oligonucleotides are an attractive alternative to antisense as a therapeutic modality because of their robust, gene selective silencing of drug target protein expression. To achieve therapeutic success, however, several hurdles must be overcome including rapid clearance, nuclease degradation, and inefficient intracellular localization. In this presentation, we discuss design strategies for development of self-assembling nanoscale carriers for neovasculature targeted delivery of siRNA inhibiting tumor or ocular angiogenesis.

Effects of treatment with small interfering RNA on joint inflammation in mice with collagen-induced arthritis.

Objective: RNA interference is a process in which genes can be silenced sequence-specifically. In mammals, RNA interference can be invoked by introduction of small (19-21-nucleotide) double-stranded RNA molecules known as small interfering RNA (siRNA) into cells. Thereby, siRNA offers promise as a novel therapeutic modality.

Highly branched HK peptides are effective carriers of siRNA.

Background: Both viral and nonviral carriers have been used to carry small interfering RNA molecules (siRNA) to their cytosolic mRNA target. To date, few peptide carriers have been developed that have proved effective for siRNA delivery. Our previous branched carriers composed of histidine and lysine were useful for transfection of plasmids.

Inhibition of ocular angiogenesis by siRNA targeting vascular endothelial growth factor pathway genes: therapeutic strategy for herpetic stromal keratitis.

Ocular neovascularization often results in vision impairment. Frequently vascular endothelial cell growth factors (VEGFs) are mainly responsible for the pathological neovascularization as in the case in neovascularization induced by CpG oligodeoxynucleotides and herpes simplex virus infection in this report. siRNAs targeting either VEGFA, VEGFR1, VEGFR2, or a mix of the three were shown to significantly inhibit neovascularization induced by CpG when given locally or systemically.

Cancer siRNA therapy by tumor selective delivery with ligand-targeted sterically stabilized nanoparticle.

Potent sequence selective gene inhibition by siRNA 'targeted' therapeutics promises the ultimate level of specificity, but siRNA therapeutics is hindered by poor intracellular uptake, limited blood stability and non-specific immune stimulation. To address these problems, ligand-targeted, sterically stabilized nanoparticles have been adapted for siRNA. Self-assembling nanoparticles with siRNA were constructed with polyethyleneimine (PEI) that is PEGylated with an Arg-Gly-Asp (RGD) peptide ligand attached at the distal end of the polyethylene glycol (PEG), as a means to target tumor neovasculature expressing integrins and used to deliver siRNA inhibiting vascular endothelial growth factor receptor-2 (VEGF R2) expression and thereby tumor angiogenesis.

Pharmaceutical prospects for RNA interference.

RNA interference has proven to be a powerful tool in gene function validation. Recently, the first studies were published reporting a disease-modulating activity of the technique, suggesting a promise for RNA interference as a novel therapeutic strategy. This review discusses the recent advancements in realizing the clinical utility of RNA-interference.

New cationic lipids form channel-like pores in phospholipid bilayers.

Two representatives of a new class of cationic lipids were found to have high pore-forming activity in planar bilayer membranes. These molecules, called BHHD-TADC and BHTD-TADC, have qualitatively similar effects on phospholipid membranes. Addition of 2.