Search Results (177)

Background/Objectives: The pandemic caused by SARS-CoV-2 boosted the development of different vaccine models. In parallel, yeasts stand out as a vaccine platform in healthcare biotechnology. Species such as Saccharomyces cerevisiae and Pichia pastoris can express heterologous proteins, which are capable of inducing specific antibodies and can perform as an attractive vaccine vehicle with immunomodulating properties due to their cell wall composition. Furthermore, the yeast surface display system facilitates antigen presentation to immune cells. We developed an oral vaccine based on P. pastoris displaying a synthetic antigen composed of Spike and Nucleocapsid epitopes. Methods: The vaccine was administered to BALB/c mice. Systemic immune response was measured through antibody detection in blood samples, and mucosal immunity was assessed via IgA levels in feces. Histopathological analysis of intestinal and gastric tissues was also conducted. Results: The yeast-based vaccine elicited a humoral immune response, reflected in the production of neutralizing antibodies and elevated levels of IgG2a and IgG2. No structural alterations or pathological changes were observed in gastrointestinal tissues. Conclusions: This study demonstrates the feasibility of using P. pastoris as an oral vaccine delivery system, supporting previous findings with other yeast species such as Saccharomyces cerevisiae, and highlighting its potential in developing effective mucosal vaccines. Full article

This narrative review explains the history of anaphylactic or hypersensitivity reactions, their connection to the cardiovascular system, and Kounis syndrome, which is linked to hypersensitivity. Additional subjects discussed include immunoglobulin E and serum tryptase, common pathways of allergic and nonallergic cardiovascular events, current perspectives on Kounis syndrome, allergic myocardial infarction, allergic angina, and the impact of COVID-19 and its vaccination on Kounis syndrome. Kounis syndrome is a distinct kind of acute vascular disease that affects the coronary, cerebral, mesenteric, peripheral, and venous systems. Kounis syndrome is currently used to describe coronary symptoms linked to disorders involving mast cell activation and inflammatory cell interactions, such as those involving T-lymphocytes and macrophages, which further induce allergic, hypersensitive, anaphylactic, or anaphylactic insults. Platelet activating factor, histamine, neutral proteases like tryptase and chymase, arachidonic acid products, and a range of cytokines and chemokines released during the activation process are among the inflammatory mediators that cause it. Proinflammatory cytokines are primarily produced by mast cells in COVID-19 infections. Mast cell-derived proteases and eosinophil-associated mediators are also more prevalent in the lung tissues and sera of COVID-19 patients. As a modern global threat to civilization, COVID-19 is linked to chemical patterns that can activate mast cells; therefore, allergic stimuli are usually the reason. Virus-associated molecular patterns can activate mast cells, but allergic triggers are typically the cause. By activating SARS-CoV-2 and other toll-like receptors, a variety of proinflammatory mediators, including IL-6 and IL-1β, are released, potentially contributing to the pathology of COVID-19. Full article

mRNA-LNP-based COVID-19 vaccines, namely Pfizer-BioNTech’s Comirnaty and Moderna’s Spikevax, were successfully deployed to help control the SARS-CoV-2 pandemic, and their updated formulations continue to be recommended, albeit only for high-risk populations. One widely discussed aspect of these vaccines is their uniquely broad spectrum and increased incidence of adverse events (AEs), collectively referred to as post-vaccination syndrome (PVS). Although the reported PVS rate is low, the high number of administered doses among healthy individuals has resulted in a substantial number of reported vaccine-related injuries. A prominent manifestation of PVS is multisystem inflammation, hypothesized to result from the systemic transfection of organ cells with genetic instructions for a toxin, the spike protein, delivered with lipid nanoparticles (LNPs). In this narrative review, we focus on endothelial cells in the microcirculatory networks of various organs as primary sites of transfection with mRNA-LNP and consequent PVS. We outline the anatomical variations in the microcirculation contributing to the individual variability of symptoms and examine the molecular and cellular responses to vaccine nanoparticle exposure at the endothelial cell level with a focus on the pathways of a sustained cascade of toxic and autoimmune processes. A deeper understanding of the mechanisms underlying mRNA-LNP-induced AEs and PVS at the organ and cellular levels is critical for improving the safety of future vaccines and other therapeutic applications of this groundbreaking technology. Full article

Background/Objectives: Opioid use disorder (OUD) remains a severe health problem globally, resulting in substantial social and economic challenges. While existing medications for managing OUD are proven to be effective, they also present certain challenges. A vaccine offers a promising therapeutic strategy to combat OUD and potentially reduce the risk of overdose death. The TT-6-AmHap heroin conjugate vaccine has effectively reduced heroin-induced pharmacological effects in behavioral assays as well as demonstrated the induction of high titer and high affinity antibody responses in mice and rats. In this GLP study conducted in rabbits, the potential local and systemic toxicity of the TT-6-AmHap heroin vaccine in combination with or without adjuvants ALF43 and Alhydrogel^® (ALFA) was investigated. Methods: Male and female New Zealand White rabbits were administered with vaccines or a saline control intramuscularly at two-week intervals over a 57-day study period. The presence, persistence or reversibility of any toxic effects of the vaccine was determined over a four-week recovery period. Results: Administration of TT-6-AmHap with or without the adjuvants induced high antibody-specific IgG in treatment groups compared to the controls. The study found no TT-6-AmHap-related effects on mortality, physical examinations, dermal Draize observations, body weights, body weight changes, food consumption, ophthalmology, clinical pathology (hematology, coagulation, clinical chemistry, and urinalysis), macroscopic pathology, or organ weights. Conclusions: Under the conditions of this study, these results demonstrate that the TT-6-AmHap vaccine with or without adjuvants was well tolerated, immunogenic, and the effects were not considered adverse in both male and female rabbits. Full article

The enterovirus Coxsackievirus B3 causes a range of serious health problems, including aseptic meningitis, myocarditis, and pancreatitis. Currently, Coxsackievirus B3 has no targeted antiviral treatments or vaccines, leaving supportive care as the primary management option. Understanding how Coxsackievirus B3 interacts with and alters the blood–brain barrier may help identify new therapies to combat this often-devastating infection. We reanalyzed a previously published RNA sequencing dataset for Coxsackievirus B3-infected human-induced pluripotent stem-cell-derived brain endothelial cells (iBECs) to examine how Coxsackievirus B3 altered mRNA expression. By integrating GSEA, EnrichR, and iLINCs-based perturbagen analysis, we present a novel, systems-level approach to uncover potential drug repurposing candidates for CVB3 infection. We found dynamic changes in host transcriptomic response to Coxsackievirus B3 infection at 2- and 5-day infection time points. Downregulated pathways included ribosomal biogenesis and protein synthesis, while upregulated pathways included a defense response to viruses, and interferon production. Using iLINCs transcriptomic analysis, MEK, PDGFR, and VEGF inhibitors were identified as possible novel antiviral therapeutics. Our findings further elucidate Coxsackievirus B3-associated pathways in (iBECs) and highlight potential drug repurposing candidates, including pelitinib and neratinib, which may disrupt Coxsackievirus B3 pathology at the blood–brain barrier (BBB). Full article

Background: Influenza remains a persistent public health challenge due to antigenic drift and shift, necessitating vaccines capable of eliciting broad and durable immunity. Hemagglutinin (HA) antigen serves as the critical target for eliciting protective immune responses against influenza. DNA vaccines offer distinct advantages over conventional platforms, including accelerated development and induction of both humoral and cellular immune responses. Methods: To optimize HA antigen presentation, we designed and systematically compared the immunogenicity and protective efficacy of HA antigen display strategies—bacteriophage T4 fibritin (HA-Foldon) and ferritin-based virus-like particles (HA-Ferritin)—versus monomeric HA DNA vaccines against seasonal influenza viruses. Results: HA-Ferritin showed superior structural stability. All vaccines induced similar HA-specific antibody levels, but HA-Ferritin elicited higher neutralizing antibodies and stronger T cell responses. Upon challenge, HA-Ferritin and HA-Foldon protected mice from weight loss and reduced lung virus loads by 3.27 and 0.76 times, respectively. Monomeric HA provided limited protection, with only 40% survival and minimal viral or pathological reduction. Conclusions: The HA-Ferritin DNA vaccine demonstrated enhanced immunogenicity and protection, supporting structured antigen display as a promising strategy for influenza DNA vaccine development. Full article

Background: Retinal vascular occlusion (RVO) and retinal artery occlusion (RAO) have been reported as rare adverse events following COVID-19 vaccination, raising concerns about vaccine safety. This review synthesizes cohort and case–control studies assessing the association between COVID-19 vaccines and RVO/RAO, while exploring potential pathophysiological mechanisms. Methods: We analyzed large-scale population-based studies from South Korea, Europe, and the TriNetX database, focusing on odds ratios (OR), hazard ratios (HR), and relative risks (RR) across mRNA and adenoviral vector vaccines. Pathological processes were hypothesized based on molecular and clinical evidence. Results: Studies investigating the association between COVID-19 vaccination and retinal vascular occlusion show conflicting results; some studies report no association (e.g., OR 0.93, 95% CI 0.60–1.45), others suggest reduced risk (e.g., OR 0.80, 95% CI 0.64–0.99), and one indicates increased risk over two years (HR 2.19, 95% CI 2.00–2.39). Adenoviral vector vaccines, particularly ChAdOx1, show higher RAO incidence in specific cohorts. Proposed mechanisms include vaccine-induced immune thrombotic thrombocytopenia (VITT) via anti-PF4 antibodies, spike protein-mediated endothelial dysfunction, and adjuvant-driven inflammation. Conclusions: While causality remains unproven, temporal heterogeneity and vaccine type-specific risks warrant further investigation. Longitudinal studies with robust controls are needed to clarify these associations in the post-pandemic context. Full article

A killed, whole-cell vaccine was produced to induce immunity in dogs against leptospirosis. The vaccine, containing serovar Copenhageni, was produced and administered to 12 beagle dogs at both 8 and 12 weeks of age. Ten unvaccinated dogs of the same age group served as the control group. A live, virulent inoculum of Leptospira (1.52 × 10⁹–4.40 × 10⁹ leptospires per dog) was used to challenge the dogs at 2 weeks (Study 1) and 14 months (Study 2) post-booster vaccination. At regular intervals, pre- and post-challenge (PC), the microscopic agglutination test (MAT) was performed to measure antibody titers. Leptospiremia and leptospiruria were determined via culture, and the cytokine, biochemical, and pathological profiles of vaccinates and controls were also assessed. A high antibody response was measurable after booster administration. In Study 1 (onset of immunity), acute leptospirosis was observed in five (100%) out of five unvaccinated dogs. In contrast, no acute clinical leptospirosis developed in vaccinated dogs, except in one (20%) dog with mild clinical signs. In Study 2 (duration of immunity), mild clinical signs were observed in two (40%) of the control dogs, while all vaccinated dogs remained clinically normal. The incidence of leptospiruria and leptospiremia PC was lower in the vaccinated dogs compared to the unvaccinated group. Severe thrombocytopenia occurred in 100% (5/5) of the unvaccinated dogs in Study 1 that exhibited acute severe leptospirosis, whereas 80% (4/5) of the unvaccinated dogs in Study 2 showed mild to moderate thrombocytopenia 3 days after challenge. Four out of five unvaccinated dogs (80%) in Study 1 exhibited icteric tissues and hemorrhages in the lungs and mucosal surfaces of the stomach and intestines. A high IL-10 to TNF-α ratio, observed in the control group of both studies, and severe thrombocytopenia observed in the control group of Study 1, indicative of acute leptospiral disease, were detected. The vaccine prevented acute clinical leptospirosis and reduced the renal carrier state in beagle dogs, and further investigation is required using a larger sample size. Full article

Vaccine-induced thrombotic thrombocytopenia (VITT) is a rare thrombotic disorder first identified in 2021 as a catastrophic syndrome associated with anti-SARS-CoV-2 adenoviral vector (AdV)-vaccine administration. It is characterized by the presence of oligo- or monoclonal anti-PF4 antibodies able to induce in vitro platelet activation in the presence of PF4. In addition to this immune-based pathomechanism, random splicing events of the Adv-vector DNA encoding for SARS-CoV-2 spike protein resulting in the secretion of soluble spike variants have been postulated as a possible pathophysiological mechanism. More recently, some novel clinical-pathological anti-PF4-associated entities also characterized by thrombosis, thrombocytopenia, and VITT-like antibodies but independent from heparin or AdV-vaccine administration have been identified. To date, these VITT-like disorders have been reported following the administration of vaccines different from anti-SARS-CoV-2 AdV-vaccines, like human papillomavirus (HPV) and mRNA-based COVID-19 vaccines, following a bacterial or viral respiratory infection, and in patients with a monoclonal gammopathy of undetermined significance. The purpose of this review is to provide an update on the knowledge on VITT pathogenesis, focusing on recent findings on anti-PF4 antibodies, on a possible genetic predisposition to VITT, on VITT-antibody intracellular activated pathways, on lipid metabolism alterations, and on new VITT-like disorders. Full article

Background: The transmembrane fusion (F) protein of RSV plays important roles in RSV pathogenesis as it mediates the fusion between the virus and the target cell membrane. During the fusion process, the F protein transits from a metastable state (prefusion, preF) to a stable state (postfusion, postF) after the merging of the virus and cell membranes. The majority of highly neutralizing antibodies induced by natural infection or immunization target the preF form, which makes it the preferred antigen for vaccine development. Methods: Here, we designed an effective RSV mRNA vaccine, STR-V003, consisting of mRNA encoding preF protein in lipid nanoparticles (LNPs). The immunogenicity, protection efficacy and toxicity were measured in multiple animal models. Results: STR-V003 demonstrated robust immunogenicity in both mice and cotton rats, inducing high levels of neutralizing antibodies and RSV preF-specific IgG antibodies and significantly reducing the RSV viral loads in the lung and nose tissue of challenged animals. In addition, STR-V003 did not show significant enhancement of lung pathology without causing vaccine-enhanced disease (VED). The repeated dose general toxicology studies and local tolerance studies of STR-V003 were evaluated in rats and non-human primate (NHP). Conclusions: STR-V003 demonstrates a favorable safety profile and induces robust protective immunity against RSV. Full article

Background/Objectives: The emergence of multidrug-resistant Acinetobacter baumannii (MDR A. baumannii) as a leading cause of fatal hospital-acquired infections underscores the urgent need for effective vaccines. While oral vaccines using live Bacillus subtilis spores expressing A. baumannii TonB-dependent receptor (TBDR) show promise, biosafety concerns regarding recombinant spore persistence necessitate alternative strategies. Here, we evaluated chemically inactivated B. subtilis spores displaying TBDR as a safer yet immunogenic vaccine candidate. Methods: Recombinant spores were inactivated using iron-ethanol sporicidal solution and administered to BALB/c mice (8–12 weeks old) to assess safety and immunogenicity. Toxicity was evaluated through clinical monitoring, serum biochemistry, and histopathology. Immune responses were characterized by T/B cell activation, IgG/IgA titers, and mucosal sIgA levels. Protective efficacy was determined by challenging immunized mice with MDR A. baumannii Ab35 and quantifying bacterial loads and examining tissue pathology. Results: The inactivated spores exhibited an excellent safety profile, with no adverse effects on clinical parameters, organ function, or tissue integrity. Immunization induced robust systemic and mucosal immunity, evidenced by elevated CD4+/CD8+ T cells, B cells, and antigen-specific IgG/IgA in serum and mucosal secretions. Following the challenge, vaccinated mice showed significantly reduced pulmonary bacterial burdens (>90% reduction), and preserved lung and spleen architecture compared to controls, which developed severe inflammation and tissue damage. Conclusions: These findings demonstrate that inactivated B. subtilis spores expressing TBDR are a safe, orally administrable vaccine platform that elicits protective immunity against MDR A. baumannii. By addressing biosafety concerns associated with live spores while maintaining efficacy, this approach represents a critical advance toward preventing high-risk nosocomial infections. Full article

Background: Outer Membrane Vesicles (OMVs), nanosized particles derived from Gram-negative bacteria, are promising vaccine carriers due to innate immunogenicity and self-adjuvant properties. Yet the systematic evaluations of OMV-associated toxicity remain limited. Methods: We developed a CRISPR/Cas9-engineered Salmonella enterica serovar Typhimurium ΔmsbB mutant (Mut4_STM) to produce detoxified OMVs (Mut4_OMVs) with enhanced yield. Subcutaneous immunization of BALB/c mice with Mut4_OMVs to evaluate safety, and the adjuvant efficacy was also determined by injecting Mut4_OMVs with Yersinia pestis F1Vmut or Bacillus anthracis PA_D4 antigens, mixing formulation, respectively. Results: Mut4_OMVs showed a 9-fold protein yield increase over wild-type OMVs. While all mice injected with wild-type OMVs died, 100% survival was observed in those receiving Mut4_OMVs. However, dose-dependent pathological alterations became evident in specific organs as the administration dose escalated, such as induced splenic extramedullary hematopoiesis and renal edema. Despite residual toxicity, 2–3 doses of 10 μg Mut4_OMVs elicited antigen-specific antibody titers comparable to aluminum adjuvant controls and superior T-cell immune responses. Conclusion: While Mut4_OMVs retain potent adjuvant activity, their residual toxicity necessitates further biocompatibility optimization for safe vaccine applications. Full article

Lyme disease (LD), caused by infection with the tick-borne bacteria, Borrelia burgdorferi, is associated with a wide array of symptoms in human patients. Variations in clinical manifestations are thought to be influenced by genetic differences among B. burgdorferi strains. In this study, we evaluated the infectivity, tissue bacterial load, pathology, and immunogenicity of five strains of B. burgdorferi sensu stricto (297 Ah130, Bb16-54, B31-A3, Bb16-126, JD1) in female C3H/HeN mice at three infectious doses (10⁴, 10⁵, 10⁶ spirochetes). We found that strains Bb16-126 and JD1 were the most infectious, resulting in 100% infection across all the tested doses. Strain Bb16-126 caused the highest bacterial burden in the heart tissue and significant carditis, whereas JD1 exhibited the lowest spirochete load in the heart and minimal carditis. In comparison, strain B31-A3 demonstrated the highest abundance in the tibiotarsal joint. Infection with all the strains induced severe lymph node hyperplasia, with JD1 producing the greatest increase in cellularity. Using a diagnostic C6 peptide ELISA, all the strains induced significant anti-C6 IgM and IgG antibody titers at 14 days post-infection; however, strain B31-A3 elicited the highest anti-C6 IgM titers. Our findings demonstrate the importance of strain diversity in shaping B. burgdorferi pathogenesis in a mouse model and provide insights for developing strain-specific diagnostic, therapeutic, and vaccine strategies. Full article

Background: Since 2011, re-emerging pseudorabies virus (PRV) variant strains have been widespread in swine herds immunized with the classical PRV vaccine in China, suggesting that it is necessary to develop a new vaccine against these PRV variant strains. Methods: Here, based on a PRV mutant strain isolated in Jinmen (JM), two recombinant strains were constructed using CRISPR/Cas9 technology, including PRV-JM-ΔEK with the deletion of the gE and TK genes and PRV-JM-ΔEI92K with the deletion of the gE, gI, US2, US9, and TK genes. Results: A one-step growth curve and plaque assay revealed that the cell-to-cell transmission ability of PRV-JM-ΔEI92K was lower than that of PRV-JM-ΔEK. However, the replication ability of PRV-JM-ΔEI92K was approximately 10 times higher than that of PRV-JM-ΔEK, similar to wild-type PRV-JM. The intramuscular injection of 10⁶ TCID₅₀ of PRV-JM-ΔEK or PRV-JM-ΔEI92K could not cause death in mice, and both could produce specific antibodies against gB and gD. The survival rate of mice immunized with both recombinant viruses was 100% when the mice were challenged by the PRV-JM strain. Histopathological sections from the PRV-JM-ΔEK group showed milder pathological changes compared to the PRV-JM-ΔEI92K group, proving that PRV-JM-ΔEK provided more effective protection. In pigs injected with 10⁶ TCID₅₀ of PRV-JM-ΔEK or PRV-JM-ΔEI92K, their body temperature did not rise, and their weight gain was not affected. Both recombinant viruses could induce the production of gB- and gD-specific antibodies and neutralizing antibodies. After the challenge of the PRV-JM virus, neutralizing antibody production was rapidly induced and lasted for at least 3 weeks. Pigs immunized with both PRV-JM-ΔEI92K and PRV-JM-ΔEK had a 100% survival rate, demonstrating that both recombinant viruses could provide effective protection. Conclusions: Compared with PRV-JM-ΔEK, PRV-JM-ΔEI92K had better safety. In conclusion, we constructed two PRV recombinant viruses, which have the potential to be used as a live carrier vaccine. Full article

Tilapia lake virus (TiLV) poses a major threat to global tilapia aquaculture and contributes to significant economic losses due to the absence of effective vaccines and treatments. Given the high mortality rates and severe pathological effects of TiLV on tilapia, alternative strategies, such as immunoglobulin-based therapies, are being considered for disease control. In this study, we developed specific immunoglobulin Y (IgY) antibodies against TiLV and evaluated their neutralization activity. Laying hens were immunized via intramuscular injections of recombinant TiLV segment 4 protein, and IgY antibodies were extracted and purified from their egg yolks using polyethylene glycol precipitation. Western blot analysis confirmed the specificity of the IgY, which demonstrated no cross-reactivity with nontarget proteins. Neutralization assays revealed a dose-dependent reduction in TiLV infectivity, which declined from 5.01 × 10⁶ TCID₅₀/mL to 5.01 × 10⁴–1.26 × 10⁵ TCID₅₀/mL, with the highest efficacy observed at a 1:2 dilution. Despite the variability in neutralization infectivity among the different hens, IgY effectively inhibited TiLV-induced cytopathic effects. Immunofluorescence assays further confirmed a significant reduction in the TiLV antigen levels in IgY-treated RHTiB cells. Our findings highlight IgY as a promising strategy for TiLV control and suggest its potential application in the prevention of emerging viruses. Full article