Search Results (933)

Messenger RNA (mRNA) entered clinical medicine through vaccines, where the innate immune reactivity that complicates protein therapeutics acts as a built-in adjuvant. The success of the coronavirus disease 2019 (COVID-19) mRNA vaccines inspired an expansive vision of an mRNA 2.0 era extending the modality to rare and common diseases, with delivery framed as the principal challenge. This review accepts much of that vision but argues it rests on an unstated assumption: that all protein therapeutics form a single pharmacological class. They do not. We propose a taxonomy, the Dose–Response Architecture Classification, separating two classes. Exposure-controlled therapeutics require a specific quantity of active protein on a defined regimen, as outcomes depend on reproducible exposure; examples include insulin, erythropoietin, growth hormone, coagulation factors, and narrow-therapeutic-index biologics. Threshold-response therapeutics depend on surpassing a functional threshold rather than maintaining a precise concentration; these include vaccines, many enzyme-replacement therapies, genome editing, receptor-saturating antibodies, and immune-cell reprogramming. Because an mRNA drug is dosed as an instruction, and a single message is translated into a variable number of proteins through a multiplicative, stochastic intracellular chain, the dose-to-effect relationship is inherently variable. Our central, deliberately falsifiable proposition is that mRNA is suitable for threshold-response therapeutics but unsuitable for exposure-controlled therapeutics unless a construct or delivery system demonstrates validated post-delivery output control within predefined pharmacokinetic and pharmacodynamic limits. This is a pharmacological boundary, not a delivery obstacle. We conclude that the greatest advances in mRNA 2.0 will come not from delivery alone but from disciplined indication triage by class. Full article

We report the first documented case of extreme, intact parathyroid hormone (PTH)-independent hypercalcemia mediated by a rare non-osteoclastic bone remodeling mechanism in a 65-year-old Puerto Rican woman, detected within 24 h of the second dose of the Moderna mRNA-1273 COVID-19 vaccine and leading to the diagnosis of high-risk biclonal IgA plasma cell myeloma (R-ISS Stage III). Peak serum calcium reached 17.4 mg/dL with concurrent hyperphosphatemia, normal lactate dehydrogenase (LDH), and without marrow osteoclasts or osteolytic lesions, findings inconsistent with classical cancer-associated hypercalcemia. Hypercalcemia resolved within eight days with supportive treatment alone, remaining durably normal nine months later. The temporal proximity to vaccination, together with the biochemical–histopathological profile, generates the hypothesis, without implying causation, that a vaccine-induced innate immune response triggered a rare inflammatory osteocytic perilacunar/canalicular remodeling. The biclonal gammopathy, Clone-1 (normal karyotype, CD33⁺, OCT-2⁺, MYC⁻, CD19⁺, PAX5⁻) and Clone-2 (complex high-risk karyotype, OCT-2⁻, MYC⁺low, CD19⁻), suggests epigenetic rather than genomic drivers in the predominant clone. This case proposes a novel mechanistic hypothesis for vaccine-associated hypercalcemia and generates testable questions that warrant prospective investigation. Full article

Virus-like particles (VLPs) based on the capsid protein (CP) of the ssRNA bacteriophage Beihai32 represent a promising nanoscale platform for the presentation of heterologous peptides. Previous studies have shown that the C-terminus of the CP tolerates long insertions without compromising VLP assembly. Here, we demonstrate that the N-terminus is similarly permissive to extended insertions. Hybrid CPs with one to four copies of the influenza A virus M2e peptide fused to the N-terminus were expressed in Escherichia coli. Fusion proteins containing four copies of M2e self-assembled into spherical VLPs, displaying the inserted peptides on the surface. Subcutaneous immunization of mice with chimeric VLPs induced high titers of M2e-specific antibodies. Unlike C-terminal fusions, the N-terminal insertion prevented the induction of anti-carrier antibody response indicting masking of the carrier protein in the chimeric VLP. To evaluate the capacity of the N-terminus for larger inserts, green fluorescent protein (GFP, 238 a.a.) was attached to the N-terminus of CP. The hybrid protein was expressed in Escherichia coli and formed VLPs. GFP was displayed on the particle surface and retained fluorescent activity. Overall, the phage Beihai32 CP is a versatile platform for the presentation of peptide antigens, supporting its potential application in VLP-based vaccine design. Full article

The innate immune system provides the first line of defense against invading pathogens and relies on tightly regulated mechanisms to initiate and resolve inflammatory responses. In addition to transcriptional control, post-transcriptional regulation of messenger RNA (mRNA) plays a critical role in determining the magnitude and duration of immune responses. Among those key regulators, the ZFP36 family of CCCH-type zinc-finger RNA-binding proteins, including ZFP36, ZFP36L1, and ZFP36L2, plays a central role in controlling the stability and translation of inflammatory, immune-related, and viral RNAs. This review focuses on the ZFP36 family of RNA-binding proteins and highlights their emerging roles in inflammation, immune cell development and differentiation, and antiviral immunity, with a particular focus on ZFP36L1 and ZFP36L2. Recent evidence has identified ZFP36L1 as a broad-spectrum antiviral factor that restricts multiple RNA viruses through distinct molecular mechanisms. A detailed understanding of the molecular mechanisms underlying ZFP36L1- and ZFP36L2-mediated antiviral activity and immune regulation will facilitate rational development of host-directed antiviral therapeutics and their strategic integration with vaccination strategies to limit viral replication, shedding, and transmission, thereby improving the control of emerging and re-emerging viral diseases. Full article

Orf virus (ORFV) is a major pathogen in goats and sheep, and control currently depends mainly on commercial live vaccines. Although mRNA vaccines have revolutionized human medicine, their use in veterinary settings is largely unexplored. In this study, an mRNA vaccine candidate encoding the ORFV F1L protein (F1L-mRNA-LNP) was developed via in vitro transcription and encapsulated in lipid nanoparticles. BALB/c mice were divided into five groups (n = 14 each): three receiving different doses of F1L-mRNA-LNP (5, 10, or 15 μg), one receiving a commercial live vaccine (CV), and a PBS control group. Mice were immunized intramuscularly and boosted after 14 days; immune responses were assessed 14 days later following ARRIVE 2.0 guidelines. Both the F1L-mRNA-LNP and CV vaccines induced specific antibodies versus PBS (p < 0.01). The 10 μg mRNA group showed Th1 cytokine and CD8⁺ T cell responses comparable to CV (p > 0.05), whereas IL-4 (Th2) was significantly higher in the CV group (p < 0.05). Neutralizing antibody titers did not differ between groups, indicating that the mRNA vaccine induces comparable Th1 cellular immunity but weaker Th2 humoral immunity. Upon ORFV challenge, the 10 μg F1L-mRNA-LNP vaccine protected BALB/c mice, as evidenced by stable body weight, no clinical symptoms, and reduced viral load, with efficacy comparable to CV (p > 0.05). This study provides strong evidence supporting the optimization of ORFV mRNA vaccines and highlights the translational potential of the F1L-mRNA-LNP candidate vaccine for veterinary applications. Full article

Messenger RNA (mRNA) vaccines represent a transformative platform in vaccinology, with applications extending beyond SARS-CoV-2 to other infectious diseases and cancer immunotherapy. However, patients with solid tumors receiving active anticancer treatment were largely underrepresented in pivotal vaccination trials, limiting understanding of vaccine-induced immunity in this population. In this prospective exploratory study, we assessed humoral and cellular immune responses after two doses of SARS-CoV-2 mRNA vaccines in 39 patients with solid tumors undergoing active treatment. Blood samples were collected before vaccination and approximately two months after the second vaccine dose, prior to the next treatment cycle. Anti-spike IgG, neutralizing antibodies, receptor-binding domain (RBD) levels, interleukin-6 (IL-6), hematological parameters, immune cell subsets, T-cell differentiation, and early apoptosis in αβ and γδ T-cell subsets were analyzed. Vaccination induced a robust humoral response, with high post-vaccination anti-spike IgG levels (median 988.69 BAU/mL), 97.44% seropositivity, 96.88% true seroconversion among baseline IgG−/NAb− patients, and strong neutralizing antibody activity (median 85.73%). Hematological parameters and IL-6 levels remained broadly stable, suggesting no detectable increase in systemic inflammation during the study period. Cellular analyses identified a reduction in peripheral CD19+ B-cell frequencies and decreased early apoptosis, particularly in CD8+ T cells and CD3+CD56+ NKT-like cells. Although changes in T-cell frequencies and differentiation profiles were also observed, these findings were attenuated after exclusion of participants with possible prior SARS-CoV-2 exposure and should be interpreted as exploratory. Overall, these results show that patients with solid tumors receiving active treatment can mount robust humoral responses to SARS-CoV-2 mRNA vaccination and suggest measurable post-vaccination changes in lymphocyte dynamics, including reduced early T-cell apoptosis. Full article

Background: Despite the circulation of evolutionarily related cold-causing coronaviruses (CCCs) in the pre-COVID era, most individuals lacked pre-existing serum IgG and/or class-switched memory B cell (B_mem) reactivity for the SARS-CoV-2 Spike (S) glycoprotein expressed by the ancestral Wuhan-Hu-1 (WH1) strain. Subsequent priming of the immune system through natural infection or prophylactic COVID-19 mRNA vaccination successfully generated robust B_mem responses against the WH1-S antigen, along with eliciting cross-reactivity for the future Omicron (BA.1) variant responsible for breakthrough infections (BTIs). However, to what extent immunological imprinting of B_mem towards the WH1-S antigen detrimentally constrains the elicitation of variant-specific antibody responses following subsequent booster vaccinations or BTIs—a phenomena referred to as “original antigenic sin”—remains an unresolved and open question. Methods: Using ImmunoSpot^®, we evaluated peripheral blood mononuclear cells (PBMCs) from defined human cohorts for IgG⁺ ASC reactivity against Spike proteins representing CCCs and SARS-CoV-2. Additionally, we developed a novel dual-label inverted FluoroSpot assay to distinguish between strain-specific and cross-reactive IgG⁺ ASCs recognizing epitopes in the receptor binding domain (RBD) of SARS-CoV-2 Omicron variants. Results: Our data demonstrate a lack of appreciable back-boosting of IgG⁺ B_mem recognizing structurally conserved epitopes shared between CCCs and SARS-CoV-2. Moreover, we found evidence for immunological imprinting and the preferential expansion of B_mem recognizing cross-reactive epitopes in the RBD following BTI. Nevertheless, Omicron strain-specific B_mem were detected in PBMC donors collected in 2025. Conclusions: Our novel inverted dual-label FluoroSpot methodology evidenced preferential expansion of cross-reactive B_mem following breakthrough SARS-CoV-2 infection and supports the influence of original antigenic sin shaping the recall response. Moreover, the inverted dual-label assay provides a highly flexible and easily implementable technique for distinguishing between strain-specific and cross-reactive B cell responses and has broad applications in translational vaccine research against pathogens that undergo antigenic drift. Full article

Respiratory mucosal vaccination can induce robust humoral and cellular immune responses, as well as effective mucosal immunity at the primary site of pathogen entry, and has been shown to provide superior protection against respiratory viral infections compared with traditional approaches. Among current vaccine technologies, mRNA vaccines offer unique advantages, including rapid development, flexible antigen design, and potent immunogenicity. However, efficient mucosal delivery of mRNA remains challenging due to biological barriers within the respiratory tract, including mucus clearance, limited cellular uptake, and instability during aerosolization. Furthermore, mRNA formulations intended for respiratory mucosal delivery require more stringent safety and tolerability profiles. Recent advances in nanoparticle engineering have accelerated the development of mRNA delivery systems optimized for respiratory mucosal immunization. This review aims to evaluate how nanoparticle engineering strategies can overcome respiratory mucosal barriers and improve the safety, stability, delivery efficiency, extrahepatic expression, and immunogenicity of mRNA vaccines and therapeutics. We summarize recent progress in engineered mRNA nanoparticle platforms for respiratory mucosal immunity, encompassing modified lipid nanoparticles (LNPs), polymer-based mRNA nanoparticles, and hybrid nanoparticle systems, including lipid-inorganic, polymeric hybrid, and lipid-extracellular vesicle (EV) nanoparticles. We further discuss optimization strategies for mucosal mRNA delivery, including the incorporation of appropriate adjuvants, the development of polyethylene glycol (PEG) alternatives, and advanced delivery approaches. Finally, we highlight current challenges and future directions for the rational design of next-generation mRNA nanoparticle platforms that can induce durable and broadly protective mucosal immunity against respiratory viral infections. Full article

Background/Objectives: Polyethylene glycol (PEG) is widely used to enhance the stability and pharmacokinetics of nanomedicines, including lipid nanoparticle (LNP)-based mRNA vaccines. However, both pre-existing and vaccine-induced anti-PEG antibodies may compromise the efficacy and safety of PEGylated therapeutics. Methods: In this study, we analyzed the specificity and avidity of anti-PEG antibodies in human blood donor samples from Unvaccinated individuals and recipients of PEGylated mRNA-LNP vaccines (Comirnaty and Spikevax), polysorbate-containing vaccines, or vaccines lacking both PEG and polysorbates. Quantitative ELISA was used to characterize anti-PEG and anti-polysorbate IgM and IgG responses in 325 plasma samples, while an equilibrium titration method was applied to assess IgG binding to PEG molecules, micelles, and PEGylated liposomes with defined structural features in 36 plasma samples. Results: Vaccination with PEGylated mRNA-LNPs was associated with increased anti-PEG antibody levels and qualitative changes in antibody binding behavior. Anti-PEG IgG antibodies displayed progressively higher avidity toward larger and structurally more complex PEG-containing antigens, with the strongest binding observed for PEGylated liposomes. Notably, vaccinated individuals, particularly those who received Spikevax, showed increased end-group and backbone-specific avidity, as well as an enhanced ability of antibody paratopes to engage shorter PEG chains. In contrast, polysorbate-containing or PEG-free vaccines did not elicit comparable effects. Conclusions: These findings suggest that vaccination with PEGylated mRNA-LNPs is associated with the emergence of altered antibody populations with increased end-group reactivity and higher avidity toward PEG-directed immune responses, despite PEG being a synthetic, nonprotein polymer. Antibody binding to LNPs, accompanied by the emergence of high-avidity anti-PEG IgG seems to be consistent with an increased risk of adverse events, particularly following repeated vaccinations, including complement activation-related pseudoallergy (CARPA) and anaphylaxis. It may also contribute to altered immune protection against the vaccine target, underscoring the need for avidity-aware risk-benefit assessment of PEGylated therapeutics. Full article

Background: While vaccines are designed to elicit targeted immune responses, in some cases, the immunogenic molecules employed can inherently interact with broader host cellular pathways as a secondary consequence. This phenomenon can be exemplified by COVID-19 vaccines. COVID-19 vaccines, including mRNA platforms, use the SARS-CoV-2 spike protein as an immunogen to induce the production of neutralizing antibodies. The spike protein binds the ACE2 (angiotensin-converting enzyme 2) receptor on human cells, mediating viral entry and infection. ACE2 is widely expressed across multiple tissues and is a key component of the renin–angiotensin–aldosterone system (RAAS) that acts as a homeostatic regulator of systemic and local blood flow, blood pressure, cardiac function, fluid balance and immunity. Some studies have proposed the interaction between the spike protein and ACE2 as a possible contributing factor to rare adverse effects observed following COVID-19 vaccination, including myocarditis, pericarditis, thrombosis, and reported alterations in blood pressure, though these mechanisms remain to be fully elucidated. Objectives: As a proof-of-concept approach in vaccine antigen development, we engineered SARS-CoV-2 spike mutants with impaired binding to the host receptor ACE2. Methods: By rational design, we produced and validated in vitro and in vivo spike point mutants that do not effectively bind ACE2. Results: The engineered spike mutants do not effectively bind the human entry receptor ACE2 while retaining the immunogenic properties equal to or better than the wild type spike and thus generate a protective response in animals when used as a vaccination agent. Conclusions: By establishing a straightforward molecular strategy for rational vaccine design, this work demonstrates the feasibility of limiting specific antigen–host receptor interactions while maintaining immunogenicity. This approach may be applicable to future vaccination strategies where antigen interaction with host cells could potentially interfere with physiological pathways. Full article

The recurrent emergence of viral outbreaks, including SARS-CoV-2, influenza, Ebola, and respiratory syncytial virus (RSV), continues to expose critical limitations in conventional antiviral therapies, particularly in terms of targeting specificity, bioavailability, and resistance development. Nanotechnology has emerged as a transformative approach to overcome these challenges. This review provides a comprehensive and critical analysis of nanoparticle-based antiviral systems, including lipid-based, polymeric, inorganic, and hybrid nanocarriers, with a focus on their roles in enhancing drug delivery, targeting precision, and therapeutic efficacy. These platforms exert antiviral effects through multiple coordinated mechanisms, including inhibition of viral entry, suppression of replication, gene silencing, and modulation of host immune responses. The clinical success of lipid nanoparticle-based mRNA vaccines highlights the translational potential of nanotechnology, while emerging nanotherapeutic strategies demonstrate increasing versatility across diverse viral pathogens. However, key challenges—including safety, scalability, formulation stability, and regulatory constraints—continue to limit widespread clinical implementation. Overall, nanoparticle-mediated antiviral systems represent a multifunctional and adaptable platform capable of addressing the limitations of conventional therapies and enabling more effective, resilient, and precision-driven strategies for future pandemic preparedness. Full article

Background: Messenger RNA (mRNA) vaccines have emerged as a versatile platform beyond SARS-CoV-2, with expanding applications in infectious diseases and oncology. However, comprehensive evidence synthesis of non-SARS-CoV-2 mRNA vaccines remains limited. Methods: This systematic review followed PRISMA 2020 guidelines and was registered in PROSPERO (CRD420261323500). MEDLINE, Embase, Web of Science, Scopus, ClinicalTrials.gov, and WHO ICTRP were systematically searched for studies published between 1 January 2000 and 28 February 2026. Eligible studies included phase I–III clinical trials and in vivo preclinical studies evaluating non-SARS-CoV-2 mRNA vaccines. Two reviewers independently screened studies, extracted data, and assessed risk of bias using RoB 2, ROBINS-I, and SYRCLE tools. Findings were synthesized narratively because of substantial heterogeneity. Results: A total of 40 studies met the eligibility criteria and were included in the review, comprising 20 clinical studies and 20 preclinical studies. Advanced clinical programs targeted influenza and respiratory syncytial virus (RSV), with phase III trials displaying seroconversion rates above 70% with good safety profiles. Preliminary phase I studies for HIV, cytomegalovirus, rabies, and personalized cancer mRNA vaccines showed promising humoral and cellular immune responses. Preclinical studies showed strong antibody and T-cell responses against malaria, tuberculosis, Group B Streptococcus, and Zika virus. Most adverse events were mild to moderate, while serious vaccine-related adverse events were uncommon. Conclusions: Non-SARS-CoV-2 mRNA vaccines demonstrate substantial translational potential across infectious disease and oncology applications. Although the vaccine candidates have demonstrated promising immunogenicity and safety, most are in the early stages of development. This highlights the need for large trials, long-term safety follow-up and better global representation. Full article

Background: The dynamics of humoral immune responses following primary and booster COVID-19 vaccinations are crucial to understand in order to optimize vaccination strategies. This study evaluates the magnitude and durability of SARS-CoV-2-specific IgG antibody responses across different vaccines in a large cohort of Bangladeshi adults. Methods: A total of 6300 adults from nine hospitals across eight divisions of Bangladesh were enrolled. Participants received two primary doses of either ChAdOx1 nCoV-19 (Covishield, Serum Institute of India, n = 2855), mRNA-1273 (Moderna, n = 578), BNT162b2 (Pfizer-BioNTech, n = 121), or Vero-cell-inactivated (Sinopharm, n = 2746) vaccines. Booster doses were administered at one-year intervals post-primary vaccination. SARS-CoV-2 spike receptor-binding domain (RBD)-specific IgG antibody responses were measured by ELISA using serum from vaccinees at multiple time points after two primary and two booster doses. Results: A total of 3745 individuals received booster 1 (third dose), with 59% receiving heterologous boosters (a different vaccine regimen than the primary doses). Only 5.5% (n = 347) of participants received a second booster one year after the first booster (among them, 99% received BNT162b2). Our results suggest that heterologous boosters with the mRNA vaccine induced higher IgG levels than homologous boosters for individuals who received primary vaccination with adenovirus vector-based ChAdOx1 nCoV-19 or a Vero-cell-inactivated vaccine. However, in those who initially received the mRNA-based vaccine, both homologous and heterologous boosters produced comparable IgG responses. Among all vaccine types, booster immunization with the Vero-cell-inactivated vaccine induced the lowest antibody responses. Longitudinal analysis demonstrated significantly high IgG levels over the 12 months following the first booster (p < 0.0001); however, IgG levels declined significantly after the second booster dose (fourth dose). Conclusions: Heterologous boosting strategies, particularly those involving mRNA vaccines, elicit stronger and more sustained IgG responses compared to a homologous booster. However, antibody waning after the second booster highlights the need for continued monitoring and potential additional vaccine strategies. Full article

Background/Objectives: Tuberculosis, caused by Mycobacterium tuberculosis, remains a major global health challenge requiring novel prevention strategies. This study aims to developed an immunoinformatics-guided framework coupled with experimental screening to prioritize for multi-epitope mRNA vaccine design. Methods: Eight immunologically relevant antigens were computationally analyzed to predict cytotoxic (CTL) epitopes and helper T lymphocyte (HTL) epitopes. Population coverage, immune simulation, molecular docking, and normal mode analysis (NMA) were performed in silico. To evaluate peptide immunoreactivity, human IFN-γELISPOT assays were conducted using the candidate peptides, though HLA restriction was not experimentally validated. Results: The workflow identified 14 candidate CTL and 8 HTL epitopes, yielding an estimated global population coverage of 82.6% (60.7% in China; 51.2% in Indonesia). Immune simulations predicted robust humoral and Th1-associated cellular responses, though sustained CD8⁺ memory responses appeared limited. Docking and NMA suggested favorable structural interactions with TLR3 and TLR4. Crucially, the IFN-γ ELISPOT assay validated eight reactive epitopes that partially coincided with computational predictions within the tested donor group. Conclusions: This study establishes an integrated computational–experimental workflow for T cell epitope prioritization. The identified reactive epitopes provide a preliminary immunological basis and candidate pool for the future design and evaluation of multi-epitope mRNA vaccine strategies against tuberculosis. Full article

Background/Objectives: In the first months of their life, infants rely on maternal antibodies for immune protection. Breastmilk is a major source of these defenses, supplying secretory IgA, IgG, and IgM that help guard mucosal surfaces against pathogens such as SARS-CoV-2. Most studies on breastmilk immunity in the context of COVID-19 have emphasized circulating monomeric IgA, rather than the multimeric secretory IgA (sIgA) that is active at mucosal barriers. This study assessed in-depth the contribution of breastmilk antibody subtypes to SARS-CoV-2 neutralization capacity and how these profiles differ following maternal COVID-19 infection versus vaccination during pregnancy or postpartum. Methods: In this prospective cohort study, breastmilk samples were collected longitudinally from individuals who had COVID-19 during pregnancy or received COVID-19 mRNA vaccination during pregnancy or postpartum. Serological assays measured IgG, IgM, systemic IgA, and secretory IgA against SARS-CoV-2 spike and nucleocapsid antigens. Results: COVID-19 infection during pregnancy resulted in significantly higher systemic and secretory IgA levels compared to vaccination. Secretory IgA demonstrated a strong correlation with neutralization capacity. Principal component analysis revealed distinct antibody profiles in COVID-19-exposed individuals versus vaccinated cohorts, with significant overlap between pregnancy and postpartum vaccination groups. Conclusions: Although both COVID-19 vaccination and disease elicit sustained COVID-19-related antibodies in breastmilk, COVID-19 infection elicits a broader and more diverse antibody response in breastmilk, specifically with a greater secretory IgA generation. These findings support the value of maternal vaccination to safely confer mucosal immunity to neonates and the need for optimized vaccine formulations for mucosal immunity. Full article