Abstract

Background

Infectious bronchitis virus (IBV) is a highly spreading, evolving virus that induces multiple manifestations, including respiratory, urinary, and reproductive symptoms, posing a significant threat to the local poultry industry. This study evaluated a variety of IBV vaccination regimens in broilers using commercially available live attenuated vaccines such as IB Primer, 793/B (4/91), IB-VAR2, and H120 against the local novel IBV-GI-23.3 strain.

Methods

The vaccines were administered to eight groups of SPF chicks either at 1 day age or at 1+14 days of age. The birds were then challenged with the NewValley-1-EGYIBV-GI23.3-2023 strain via the oculo-nasal route at 28 days post-vaccination, using 10⁶ EID₅₀/0.2 ml/chick. Ciliostasis activity and the scores for histopathological lesions were evaluated at 7 days post-challenge (DPC). Virus shedding was monitored at 3, 5, and 7 DPC using the real-time RT-PCR method.

Results

The ciliostasis test indicated that the vaccinated groups receiving the IB Primer + 4/91 vaccine regime at 1 day age or at 1+14 days of age provided the highest levels of protection (65%, 68%). Similarly, administration of IB Primer-VAR2 at 1+14 days of age demonstrated substantial protection (63%). Conversely, administering the H120+4/91 vaccination protocol at days 1 and 14 resulted in a moderate level of protection (53%). Tracheal IBV shedding quantification and subsequent assessment of trachea, proventriculus, bursa, and kidney degenerative changes were significantly lower in the vaccinated groups than in the control groups.

Conclusion

The heterologous combined IB Primer +4/91 program demonstrated the most significant protective efficacy against the IBV field challenge strains in broiler chickens compared to other vaccines.

Introduction: Adjuvants play crucial roles in developing new and improved vaccines. Yet adjuvant discovery has been a slow process. We recently took a different approach to developing physical radiofrequency-based adjuvants (RFAs) to stimulate thermal tissue stress to enhance vaccine-induced immune responses. In murine models, RFA profoundly enhanced intradermal influenza-vaccine-induced humoral and cellular immune responses, with an adjuvant potency comparable to that of commonly used chemical adjuvants. RFA also showed potent dose-sparing effects for influenza vaccines, with an adjuvant potency superior to that of the MF59-like AddaVax adjuvant. Interestingly, the physical RFA only induced transient, low-level local inflammation without a significant change in the local proteome, in sharp contrast to chemical adjuvants. It is intriguing how RFA induces potent adjuvant effects without the induction of strong local inflammation or a significant change in the proteome.

Methods: This study focuses on uncovering the underlying action mechanisms of the physical RFA and its low-level local inflammation in murine models. Mice were subjected to RFA or Sham treatment, followed by intradermal injection of a fluorescence antigen. Inducible HSP70 expression and antigen uptake in diverse skin cell types were analyzed through flow cytometry. We further used HSP70 KO mice to evaluate the potential roles of HSP70 in antigen uptake and RFA-induced cytokine release.

Results: We found that RFA could induce rapid heat-shock protein 70 (HSP70) synthesis in the dendritic cells (DCs), which could release extracellularly and bind intradermally injected antigens. Furthermore, inducible HSP70 played crucial roles in mediating enhanced antigen uptake following RFA treatment. Interestingly, HSP70 suppressed the RFA-induced TLR4/NFκB signaling pathway and IL-6 release.

Conclusion: These studies indicate dual roles of in situ-induced HSP70 in antigen delivery and immunoregulation. This work supports the further development of alternative RFA to boost influenza vaccination with good local, systemic, and long-term safety.

The Porcine Epidemic Diarrhea Virus (PEDV) spike (S) protein is a key glycoprotein that mediates viral binding and entry, making it a prime target for subunit vaccine development. Within its S1 domain, the core neutralizing epitope (COE; residues 499–799) is rich in predicted B- and T-cell epitopes as well as neutralizing determinants, underscoring its strong immunogenic potential. This study explores whether fusing a bacterial lipoprotein signal peptide to the COE domain can enhance its antigenicity and protective efficacy by promoting lipidation-driven Toll-like receptor 2 (TLR2) activation. Two constructs were generated: COE with signal peptide (SP-COE) and COE without signal peptide. Their performance was assessed using in silico, in vitro, and in vivo approaches. Computational analyses confirmed broad B- and T-cell epitope coverage, stable structural models, and favorable receptor binding. In vitro, HEK-Blue hTLR2 reporter assays showed that SP-COE triggered significantly higher NF-κB activation compared to COE, validating enhanced TLR2 engagement. In vivo, SP-COE vaccination in mice resulted in stronger humoral and cellular immunity, evidenced by higher total IgG and virus-neutralizing antibody titers, robust cytokine responses (IFN-γ, IL-4), and increased CD4⁺ T-cell activation. Collectively, these findings indicate that incorporating a lipoprotein signal peptide augments the immunogenicity and protective performance of the PEDV COE antigen, supporting its role as a built-in adjuvant for rational subunit vaccine design.

Nanoparticles offer a versatile antigen delivery vehicle for vaccines, enhancing immune responses and promoting robust immunity. Zein is a promising material for organic nanoparticle synthesis due to its unique attributes such as biodegradability, biocompatibility, and safety due to its natural origin. In this study, the potential of zein nanoparticles (ZNPs) used as nanocarriers was evaluated for an antigenic peptide (p30) and the receptor binding domain (RBD) from SARS-CoV-2 spike protein. ZNPs were synthesized by nanoprecipitation and characterization was performed using Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM). A cytotoxicity assay in the Vero cell line was performed prior to the in vivo test. The immunogenicity of ZNP conjugates was evaluated in BALB/c mice using an immunization scheme comprising three subcutaneous doses. Two different doses of ZNP-p30 conjugates were evaluated: a low dose (5 µg) and a high dose (10 µg). With regard to the the ZNP–RBD conjugates, only a 1 µg dose was tested. Results from DLS and TEM showed evidence of ZNP formation. According to the in vitro assay, ZNPs do not compromise cellular viability. In vivo assays demonstrated that total IgG levels with either 5 or 10 µg of ZNPs:p30 had comparable titers to the positive control group, suggesting that the formulation of ZNPs has adjuvant properties similar to alum. When IgG subclasses were analyzed, IgG1 predominated over IgG2a, suggesting that a Th2-bias (humoral) response is induced. As expected, IgM was elicited after the first immunization, and decreased over time. Interestingly, the IgG antibodies produced could recognize the full spike protein of SARS-CoV-2. Regarding ZNP:RDB formulation, the results showed that the total IgG levels were comparable with the adjuvanted group. In conclusion, ZNPs are promising carriers for subcutaneous immunization with the SARS-CoV-2 antigens used, eliciting an immune response comparable to that produced by the commercial adjuvant.

Abstract

Introduction

Vaccine efficiency depends upon antigen selection and appropriate delivery platform. Various biomaterials such as nanoparticles, hydrogels and microneedles are used as vaccine delivery systems to enhance antigen stability, control release kinetics, and modulate immune responses. These systems overcome limitations of traditional administration routes by enabling precise targeting of immune cells.

Method

Studies in recent few years have evaluated the importance of nanoparticle formulations (lipid-based, polymeric, and inorganic), hydrogel matrices (thermosensitive and injectable), and microneedle arrays (solid, coated, and dissolving) in vaccine delivery. Comparative analysis of various biomaterials was studied.

Results

Nanoparticle formulation demonstrated efficient co-delivery of antigen–adjuvant combinations and balanced humoral and cellular immunity. Hydrogels are responsible for improved memory T-cell responses and reduced booster requirements by causing sustainable antigen release over days to weeks. Microneedle arrays provide access to needle-free administration with rapid uptake by skin-resident dendritic cells, eliciting robust mucosal and systemic immunity.

Conclusion

Biomaterial-based vaccine delivery systems are a transformative approach to next-generation immunization strategies. Nanoparticles, hydrogels, and microneedles can improve vaccine potency, reduce cold-chain dependence, and broaden accessibility by enabling targeted, sustained, and minimally invasive antigen presentation. Future research integrating smart biomaterials with AI-driven antigen design plays crucial role in accelerating both infectious disease and cancer vaccine development.

Introduction:
The BCG (Bacillus Calmette-Guérin) vaccine is used in Brazil to prevent severe forms of tuberculosis in children, including tuberculous meningitis and miliary tuberculosis. Under the National Immunization Program (PNI), BCG is administered in a single dose to children under one year of age, with a target coverage of 90%. Vaccination efforts are primarily conducted by the Unified Health System (Sistema Único de Saúde – SUS), Brazil’s public, free, and universal healthcare system. Vaccination coverage (VC) is an indicator that measures the proportion of the vaccinated population relative to the total eligible. It is calculated by dividing the number of doses administered by the number of eligible individuals, multiplied by 100. For BCG, the denominator is based on the number of live births recorded in the Live Birth Information System (SINASC). This study aims to analyze BCG VC in Brazil from 2016 to 2025 using data exclusively from the National Health Data Network (RNDS), an official SUS database.

Methods:
A descriptive study was conducted using secondary data from RNDS on annual BCG coverage from 2016 to 2025. Data for 2025 includes records up to May. Percentages were compared to the national target of 90% and analyzed descriptively.

Results:
From 2016 to 2018, VC remained above 90%, peaking in 2018 (99.72%). Coverage declined starting in 2019 (86.67%), reaching the lowest levels in 2020 (77.14%) and 2021 (74.97%) during the COVID-19 pandemic. Recovery began in 2022 (90.09%), with 87.99% in 2023, 96.61% in 2024, and 87.91% reported through May 2025.

Conclusion:
BCG coverage in Brazil showed significant variation over the last decade. The drop during the pandemic and subsequent recovery highlight the need for sustained immunization strategies and the strength of SUS data as a public health surveillance tool.

Introduction. Although antiretroviral therapy (ART) effectively suppresses Human Immunodeficiency Virus (HIV), it does not eliminate viral reservoirs, and lifelong ART remains necessary. We outline a conceptual framework for a therapeutic vaccine that combines two complementary strategies: (1) induction of broad antiviral immunity using conserved mosaic antigens, and (2) intracellular interference with viral replication through engineered antiviral peptides. This saRNA-LNP platform aims to achieve durable viral control without lifelong ART by simultaneously targeting immune evasion and viral replication pathways.

Methods. The proposed platform integrates (1) mosaic immunogens, such as self-amplifying RNA (saRNA) encoding computationally selected epitopes from Gag, Pol, Env, Tat and Rev, based on NetMHCpan predictions and the Los Alamos National Laboratory HIV database, aiming for broad clade coverage (>95%); and (2) antiviral peptides, including mRNA encoding inhibitors such as LEDGIN-like peptides that block integrase-LEDGF/p75 binding and dominant-negative reverse transcriptase variants (YIDD mutants). These are formulated in lipid nanoparticles (LNPs) containing DOTAP and anti-CD40 ligands to enhance dendritic cell targeting. Epitope conservation was assessed with IEDB, while Rosetta docking was used to model peptide binding to viral enzymes.

Results. In silico analyses suggest high population coverage (~98% for HLA-I/II), sustained antigen expression for over 14 days, and strong predicted peptide–enzyme interactions (Rosetta energies <–7.5 kcal/mole). BLASTp comparisons indicated low cross-reactivity with human proteins. Note that these findings are entirely in silico.

Conclusion. This conceptual design proposes a dual-function vaccine that seeks to enhance HIV-specific immune responses while simultaneously disrupting viral replication as a novel antirretroviral therapy for HIV. The approach is quite ambitious and remains at an early theoretical stage. Experimental validation will be essential to determine its feasibility as a future therapeutic vaccination strategy.

Several approaches have produced an effective vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, the durability and efficacy of the immune response against SARS-CoV-2 in aged individuals is limited. Our objective is to develop a vaccine using influenza virus-like particles (VLPs) by incorporating GPI-RBD-GM-CSF fusion protein and GPI-IL-12 by protein transfer and demonstrate its efficacy and durability against influenza and SARS-CoV-2 viruses.

We have developed a bivalent VLP vaccine for influenza and SARS-CoV-2 using VLP incorporated with glycosylphosphatidylinositol (GPI)-anchored Spike RBD of SARS-CoV-2 fused to GM-CSF as an adjuvant. GPI-anchored fusion protein of GM-CSF and the SARS-CoV-2 S1 RBD was incorporated into influenza VLPs by protein transfer to make a bivalent VLP vaccine. The efficacy of the bivalent VLP vaccine was tested in both young and aged mice.

Our results show that the bivalent VLP vaccine induced a strong antibody response and protected the mice from both influenza virus and mouse-adapted SARS-CoV-2 challenges, with vaccinated mice having less body weight loss and significantly lower lung viral titers compared to control mice. The anti-viral immunity is long lasting and protective in aged mice immunized either when they are young and allowed to age or vaccinated when they are old prior to virus challenge.

The results suggest that the bivalent VLP vaccine is a promising candidate for preventing influenza A and SARS-CoV-2 infections.

Funding:

This work was supported by NIH/NIAID (SBIR Contract# 75N93019C00017 Amendment to Pack/Ramachandiran), and Intel Corporation for the Intel COVID-19 Global Technology Response Initiative grant.

The development of a vaccine against influenza caused by highly pathogenic avian influenza (HPAI) viruses of the A/H5 subtype is a pressing issue due to concerns about the pandemic potential of this subtype. It is evident that mRNA vaccines possess a multitude of characteristics that are indispensable for the development of an influenza vaccine. In general, lipid nanoparticles (LNPs) are utilized for the delivery of exogenous mRNA into the cells of the body. Additionally, the needle-free jet injection (JI) method has emerged as a promising alternative to LNPs for mRNA delivery.

An experimental mRNA vaccine encoding a modified hemagglutinin (HA) trimer of the H5N8 influenza virus has been obtained. The HA gene was subsequently cloned into the pVAX-Cas1CC expression cassette, which carries the target gene under the control of the T7 promoter. The cassette also contains 5'- and 3'-untranslated regions of human α-globin and 100-nucleotide poly-(A)-tail. The mRNA was encapsulated in LNPs. Subsequently, BALB/c mice were immunized with mRNA delivered by LNPs and as "naked" mRNA by JI. The control groups consist of naïve mice, mice that have been immunized with a recombinant protein and LNPs without mRNA.

Studies have shown that mice, immunized with obtained mRNA delivered by LNPs and JI, can effectively stimulate humoral and T-cell immune responses. A comparative evaluation showed that mRNA-LNPs exhibited the highest levels of humoral immune response stimulation, while JI stimulated an immune response at lower levels that were nevertheless sufficient to protect animals from lethal infection with both homologous and heterologous H5Nx viruses. The data indicate that mRNA-H5 is a promising influenza vaccine candidate against the HPAI virus subtype A/H5 with pandemic potential.

This study was conducted by the Federal State Budgetary Institution State Research Center Vector of Rospotrebnadzor as part of a state assignment.

Despite considerable progress in immunization efforts, Nigeria continues to face significant challenges in delivering vaccines to remote and underserved areas. The dependence on cold-chain infrastructure, coupled with vaccine hesitancy and limited healthcare access, has hindered equitable vaccine distribution. Recent advances in thermostable and needle-free vaccine delivery platforms offer promising alternatives that can improve immunization coverage, especially in hard-to-reach populations. This study aims to assess the challenges and opportunities associated with the deployment of thermostable and needle-free vaccine delivery technologies in Nigeria, with an emphasis on their applicability in low-resource and rural settings. This is a secondary data review based on recent literature and reports from 2020 to 2024. Sources included peer-reviewed journals, WHO technical documents, and national immunization data. Key indicators analyzed include vaccine storage requirements, ease of administration, cost-effectiveness, and public health outcomes. Thermostable vaccines—formulations that remain effective without strict cold storage—have shown promise in reducing vaccine wastage and improving delivery logistics. Additionally, needle-free technologies such as microneedle patches, jet injectors, and nasal sprays have demonstrated comparable immunogenicity to traditional methods and could address needle-associated fears and safety concerns. Although pilot studies have shown efficacy and acceptance, widespread adoption in Nigeria is limited by cost, regulatory bottlenecks, and healthcare worker training gaps. Thermostable and needle-free vaccine platforms represent a transformative step toward equitable vaccine access in Nigeria. Policy reforms, investment in scalable technologies, and pilot programs are crucial for integration into national immunization schedules. Further studies should evaluate community acceptance and long-term cost-effectiveness in the Nigerian context.