Self-Assembling Sulfated Lactobacillus Exopolysaccharide Nanoparticles as Adjuvants for SARS-CoV-2 Subunit Vaccine Elicit Potent Humoral and Cellular Immune Responses.

Coronavirus disease 2019 (COVID-19) has caused a global pandemic since its onset in 2019, and the development of effective vaccines for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to induce potent and long-lasting immunity remains a priority. Herein, we prepared two Lactobacillus exopolysaccharide (EPS) nanoparticle adjuvants (NPs 7-4 and NPs 8-2) that were constructed by using sulfation-modified EPS and quaternization-modified chitosan. These two NPs displayed a spherical morphology with sizes of 39 and 47 nm. Furthermore, the zeta potentials of NPs 7-4 and NPs 8-2 were 50.40 and 44.40 mV, respectively. In vitro assays demonstrated that NPs could effectively adsorb antigenic proteins and exhibited a sustained release effect. Mouse immunization tests showed that the NPs induced the expression of cytokines and chemokines at the injection site and promoted the uptake of antigenic proteins by macrophages. Mechanically, the NPs upregulated the expression of pattern recognition receptors (toll-like receptors and nod-like receptors) and activated the immune response of T cells and the production of neutralizing antibodies. In addition, the NP adjuvants had favorable immune-enhancing effects in cats, which are of great significance for controlling the trans-host transmission and re-endemicity of SARS-CoV-2. Overall, we demonstrated that NP-adjuvanted SARS-CoV-2 receptor binding domain proteins could induce robust specific humoral and cellular immunity.

In Vivo Sustained Release of Peptide Vaccine Mediated by Dendritic Mesoporous Silica Nanocarriers.

Mesoporous silica nanoparticles have drawn increasing attention as promising candidates in vaccine delivery. Previous studies evaluating silica-based vaccine delivery systems concentrated largely on macromolecular antigens, such as inactivated whole viruses. In this study, we synthesized dendritic mesoporous silica nanoparticles (DMSNs), and we evaluated their effectiveness as delivery platforms for peptide-based subunit vaccines. We encapsulated and tested in vivo an earlier reported foot-and-mouth disease virus (FMDV) peptide vaccine (B2T). The B2T@DMSNs formulation contained the peptide vaccine and the DMSNs without further need of other compounds neither adjuvants nor emulsions. We measured in vitro a sustained release up to 930 h. B2T@DMSNs-57 and B2T@DMSNs-156 released 23.7% (135 µg) and 22.8% (132 µg) of the total B2T. The formation of a corona of serum proteins around the DMSNs increased the B2T release up to 61% (348 µg/mg) and 80% (464 µg/mg) for B2T@DMSNs-57 and B2T@DMSNs-156. In vitro results point out to a longer sustained release, assisted by the formation of a protein corona around DMSNs, compared to the reference formulation (i.e., B2T emulsified in Montanide). We further confirmed in vivo immunogenicity of B2T@DMSNs in a particle size-dependent manner. Since B2T@DMSNs elicited specific immune responses in mice with high IgG production like the reference B2T@Montanide™, self-adjuvant properties of the DMSNs could be ascribed. Our results display DMSNs as efficacious nanocarriers for peptide-based vaccine administration.

A Global Review on Short Peptides: Frontiers and Perspectives.

Peptides are fragments of proteins that carry out biological functions. They act as signaling entities via all domains of life and interfere with protein-protein interactions, which are indispensable in bio-processes. Short peptides include fundamental molecular information for a prelude to the symphony of life. They have aroused considerable interest due to their unique features and great promise in innovative bio-therapies. This work focusing on the current state-of-the-art short peptide-based therapeutical developments is the first global review written by researchers from all continents, as a celebration of 100 years of peptide therapeutics since the commencement of insulin therapy in the 1920s. Peptide "drugs" initially played only the role of hormone analogs to balance disorders. Nowadays, they achieve numerous biomedical tasks, can cross membranes, or reach intracellular targets. The role of peptides in bio-processes can hardly be mimicked by other chemical substances. The article is divided into independent sections, which are related to either the progress in short peptide-based theranostics or the problems posing challenge to bio-medicine. In particular, the SWOT analysis of short peptides, their relevance in therapies of diverse diseases, improvements in (bio)synthesis platforms, advanced nano-supramolecular technologies, aptamers, altered peptide ligands and in silico methodologies to overcome peptide limitations, modern smart bio-functional materials, vaccines, and drug/gene-targeted delivery systems are discussed.

Potential approaches to combat COVID-19: a mini-review.

The outbreak of a novel coronavirus namely SARS-CoV-2, which first emerged from Wuhan, China, has wreaked havoc not only in China but the whole world that now has been engulfed in its wrath. In a short lapse of time, this virus was successful in spreading at a blistering pace throughout the globe, hence raising the flag of pandemic status. The mounting number of deaths with each elapsing day has summoned researchers from all around the world to play their part in driving this SARS-CoV-2 pandemic to an end. As of now, multiple research teams are immersed in either scrutinizing various antiviral drugs for their efficacy or developing different types of vaccines that will be capable of providing long-term immunity against this deadly virus. The mini-review sheds light on the possible approaches that can be undertaken to curb the COVID-19 spread. Possible strategies comprise viral vector-based, nucleic acid-based, protein-based, inactivated and weakened virus vaccines; COVID-19 vaccine being developed by deploying Hyleukin-7 technology; plant-based chimeric protein and subunit vaccines; humanized nano-bodies and human antibodies; intravenous immunoglobulin (IVIG) infusion therapy; inhibitors for ACE-2, Angiotensin 1 receptor (AT1R), complement system, viral proteins, host cell protease and endocytosis; shield immunity; IL-6R, NKG2A and hACE2-SARS-CoV-2-RBD interaction blocking monoclonal antibodies; SARS-CoV RdRp-based drugs, traditional Chinese medicine, repositioned and anti-viral drugs. These vaccines and drugs are currently being screened in the clinical trials as several of them have manifested positive results, hence increasing the probability of becoming one of the potential treatments for this disease.

Poly(amino acids) as a potent self-adjuvanting delivery system for peptide-based nanovaccines.

To be optimally effective, peptide-based vaccines need to be administered with adjuvants. Many currently available adjuvants are toxic, not biodegradable; they invariably invoke adverse reactions, including allergic responses and excessive inflammation. A nontoxic, biodegradable, biocompatible, self-adjuvanting vaccine delivery system is urgently needed. Herein, we report a potent vaccine delivery system fulfilling the above requirements. A peptide antigen was coupled with poly-hydrophobic amino acid sequences serving as self-adjuvanting moieties using solid-phase synthesis, to produce fully defined single molecular entities. Under aqueous conditions, these molecules self-assembled into distinct nanoparticles and chain-like aggregates. Following subcutaneous immunization in mice, these particles successfully induced opsonic epitope-specific antibodies without the need of external adjuvant. Mice immunized with entities bearing 15 leucine residues were able to clear bacterial load from target organs without triggering the release of soluble inflammatory mediators. Thus, we have developed a well-defined and effective self-adjuvanting delivery system for peptide antigens.

Adjuvant effect of Vernonia amygdalina leaf extract on host immune response to hepatitis B virus subunit vaccine.

Aim of the study: Adjuvants can increase the efficiency and reduce the number of required doses for hepatitis B vaccination. Thus the study was designed to investigate whether V. amygdalina leaf extract may be used as an adjuvant to the conventional hepatitis B surface antigen-based vaccine through humoral response analyses. Methodology: The toxicity/safety margin of V. amygdalina was determined using Lorke's method. Immunization was carried out in mice in two phases, phase 1 employed a 3-times vaccination schedule while phase 2 tested 2-times vaccination schedule. The humoral immune response was determined using ELISA test. The total white blood count, different white blood count, aspartate aminotransferase level, alanine aminotransferase level were determined and the body weight of the mice periodically monitored. Results: Our data show that V. amygdalina was not toxic up to the dose of 5000 mg/kg bodyweight (bw). At a concentration of 250 mg/kg bw as an adjuvant in a three times vaccination schedule, it increased IgM, IgG1 and IgA antibody responses. In a 2-times vaccination schedule, 1000 mg/kg of V. amygdalina as an adjuvant to hepatitis B vaccine was able to elicit effective antibody production (0.174±0.002) significantly (P <0.05) higher than the conventional hepatitis B vaccine group (0.109±0.002) which received 3-times vaccine dose. It equally enhanced innate cell-mediated immune response by increasing total white blood cell, neutrophil and lymphocyte counts. The adjuvant-vaccine combination did not produce side effects as the aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were within the normal ranges. The liver excised from the sacrificed mice at the end of the vaccination series showed no sign of congestion, inflammation or colour change. Periodic mice body weight monitoring showed similar growth pattern between the treatment and control groups. Conclusion: Results obtained suggest that V. amygdalina may serve as an effective adjuvant to hepatitis B virus vaccine.

Engineered hybrid spider silk particles as delivery system for peptide vaccines.

The generation of strong T-cell immunity is one of the main challenges for the development of successful vaccines against cancer and major infectious diseases. Here we have engineered spider silk particles as delivery system for a peptide-based vaccination that leads to effective priming of cytotoxic T-cells. The recombinant spider silk protein eADF4(C16) was fused to the antigenic peptide from ovalbumin, either without linker or with a cathepsin cleavable peptide linker. Particles prepared from the hybrid proteins were taken up by dendritic cells, which are essential for T-cell priming, and successfully activated cytotoxic T-cells, without signs of immunotoxicity or unspecific immunostimulatory activity. Upon subcutaneous injection in mice, the particles were taken up by dendritic cells and accumulated in the lymph nodes, where immune responses are generated. Particles from hybrid proteins containing a cathepsin-cleavable linker induced a strong antigen-specific proliferation of cytotoxic T-cells in vivo, even in the absence of a vaccine adjuvant. We thus demonstrate the efficacy of a new vaccine strategy using a protein-based all-in-one vaccination system, where spider silk particles serve as carriers with an incorporated peptide antigen. Our study further suggests that engineered spider silk-based vaccines are extremely stable, easy to manufacture, and readily customizable.

Efficacy of the Herpes Simplex Virus 2 (HSV-2) Glycoprotein D/AS04 Vaccine against Genital HSV-2 and HSV-1 Infection and Disease in the Cotton Rat Sigmodon hispidus Model.

UNLABELLED: Subunit vaccines based on the herpes simplex virus 2 (HSV-2) glycoprotein D (gD-2) have been the major focus of HSV-2 vaccine development for the past 2 decades. Based on the promising data generated in the guinea pig model, a formulation containing truncated gD-2, aluminum salt, and MPL (gD/AS04) advanced to clinical trials. The results of these trials, however, were unexpected, as the vaccine protected against HSV-1 infection but not against HSV-2. To address this discrepancy, we developed a Depot medroxyprogesterone acetate (DMPA)-treated cotton rat Sigmodon hispidus model of HSV-2 and HSV-1 genital infection. The severity of HSV-1 genital herpes was less than that of HSV-2 genital herpes in cotton rats, and yet the model allowed for comparative evaluation of gD/AS04 immunogenicity and efficacy. Cotton rats were intramuscularly vaccinated using a prime boost strategy with gD/AS04 (Simplirix vaccine) or control vaccine formulation (hepatitis B vaccine FENDrix) and subsequently challenged intravaginally with HSV-2 or HSV-1. The gD/AS04 vaccine was immunogenic in cotton rats and induced serum IgG directed against gD-2 and serum HSV-2 neutralizing antibodies but failed to efficiently protect against HSV-2 disease or to decrease the HSV-2 viral load. However, gD/AS04 significantly reduced vaginal titers of HSV-1 and better protected animals against HSV-1 compared to HSV-2 genital disease. The latter finding is generally consistent with the clinical outcome of the Herpevac trial of Simplirix. Passive transfer of serum from gD/AS04-immunized cotton rats conferred stronger protection against HSV-1 genital disease. These findings suggest the need for alternative vaccine strategies and the identification of new correlates of protection. IMPORTANCE: In spite of the high health burden of genital herpes, there is still no effective intervention against the disease. The significant gap in knowledge on genital herpes pathogenesis has been further highlighted by the recent failure of GSK HSV-2 vaccine Simplirix (gD/AS04) to protect humans against HSV-2 and the surprising finding that the vaccine protected against HSV-1 genital herpes instead. In this study, we report that gD/AS04 has higher efficacy against HSV-1 compared to HSV-2 genital herpes in the novel DMPA-synchronized cotton rat model of HSV-1 and HSV-2 infection. The findings help explain the results of the Simplirix trial.

Development of a rice-based peptide vaccine for Japanese cedar and cypress pollen allergies.

Peptide immunotherapy using dominant T-cell epitopes is a safe treatment alternative to conventional subcutaneous injection of natural crude allergen extract, which is sometimes accompanied by anaphylactic shock. For Japanese cedar pollinosis (JCP), hybrid peptides composed of six to seven major T-cell epitopes (7Crp peptide) from the causative allergens Cry j 1 and Cry j 2 have been developed on the basis of different human leukemia antigen class II restrictions, because of the diversity of patients' genetic backgrounds. However, other dominant T-cell epitopes that are produced in some patients are not covered by these peptides. To develop a more universal peptide vaccine for JCP, we generated transgenic rice seeds containing seven new T-cell epitopes (Crp3) in addition to the T-cell epitopes used in the 7Crp peptide. Next, we co-expressed unique T-cell epitopes (6Chao) from the Japanese cypress pollen allergens Cha o 1 and Cha o 2 in transgenic rice seeds, with 7Crp and Crp3. These transgenic rice seeds, containing many highly homologous T-cell epitopes derived from cedar and cypress allergens, are expected to be applicable to a wide range of patients suffering from these pollen allergies.

[In vitro effect of the S3Pvac vaccine against cysticercosis in human mononucleate cells]. / Efecto in vitro de la vacuna S3Pvac contra cisticercosis en celulas mononucleares humanas.

INTRODUCTION: Neurocysticercosis (NCC) is a parasitic infection caused by the establishment of Taenia solium cysticerci in the central nervous system. The larval stage of the parasite also affects the pig, which is the essential intermediate host for transmission. For this reason, many researchers have focused on identifying protective antigens to prevent swine cysticercosis and interrupt the transmission. These include S3Pvac vaccine antigens. Vaccine is constituted by three protective synthetic peptides: KETc1, KETc12 and GK1. AIM. To evaluate the effect of the vaccine peptides KETc1, KETc12 and GK1 in mononuclear cells of patients with neuro-cysticercosis and healthy individuals. SUBJECTS AND METHODS: Comparative, prospective, transverse study. We studied the proliferation and cytokine profile induced by the three peptides in mononuclear cells from three patients with active NCC, 16 patients by calcified NCC and 16 healthy subjects. RESULTS: KETc1 induces low levels of proliferation in cells from patients with active and controlled NCC, both in lymphocytes and in monocytes. KETc12 and GK-1 induce positive proliferation levels of monocytes in healthy subjects. CONCLUSIONS: KETc1 peptide could be used as an adjuvant in the treatment of patients with active NCC, as induced a Th2 response also GK1 peptide as stimulator of monocyte/macrophage in immunizations with other proteins.

TITLE: Efecto in vitro de la vacuna S3Pvac contra cisticercosis en celulas mononucleares humanas.Introduccion. La neurocisticercosis (NCC) es una infeccion parasitaria generada por el establecimiento de cisticercos de Taenia solium en el sistema nervioso central. La fase larvaria del parasito tambien afecta al cerdo, que es el huesped intermediario indispensable para la transmision. Por tal motivo, muchos investigadores se han enfocado en identificar antigenos protectores para prevenir la cisticercosis porcina e interrumpir la transmision. Entre ellos figuran los antigenos de la vacuna S3Pvac, constituida por tres peptidos protectores: KETc1, KETc12 y GK1. Objetivo. Evaluar el efecto de los peptidos vacunales KETc1, KETc12 y GK1 en celulas mononucleares de pacientes con NCC e individuos sanos. Sujetos y metodos. Estudio comparativo, prospectivo y transversal. Se analizo la proliferacion y el perfil de citocinas inducidos por los tres peptidos en celulas mononucleares de tres pacientes con NCC activa, 16 pacientes con NCC calcificada y 16 sujetos sanos. Resultados. KETc1 induce bajos niveles de proliferacion en las celulas de los pacientes con NCC activa y controlada, tanto en linfocitos como en monocitos. KETc12 y GK-1 inducen niveles positivos de proliferacion de monocitos en sujetos sanos. Conclusiones. El peptido KETc1 podria usarse como coadyuvante en el tratamiento de los pacientes con NCC activa, ya que indujo una respuesta Th2; y el peptido GK1, como estimulador del monocito/macrofago en inmunizaciones con otras proteinas.