Search Results (457)

Background/Objectives: Pertussis, caused by Bordetella pertussis, remains a global health problem, despite high vaccine coverage. In countries with high acellular pertussis vaccine (aPV) coverage, pertactin-negative B. pertussis strains emerged due to vaccine pressure on the sole bactericidal target of aPVs. In contrast, the live attenuated intranasal vaccine BPZE1 induces bactericidal antibodies to multiple antigenic targets that kill pertactin-positive and pertactin-negative B. pertussis strains. Here, we developed two high-throughput human complement-mediated serum bactericidal assays (SBA) using clinical samples to demonstrate bactericidal activity against B. pertussis. Methods: Assay accuracy, precision, linearity, range and robustness of the SBAs against pertactin-positive and pertactin-negative B. pertussis strain B1917 were determined using a panel of commercial and clinical trial samples. The assay was used to analyze a cohort of BPZE1 and tetanus–diphtheria–acellular pertussis (Tdap) vaccinee samples at baseline and 28 days post-vaccination from a phase 2b clinical trial. Results: Inter- and intra-assay variability of both assays had coefficients of variation for repeatability < 20% and for intermediate precision of <30%. The assays measured titers ranging from ~8 to ~20,000 and showed high linearity (R² > 0.98) between bactericidal titers and serum dilutions. On clinical samples, BPZE1 induced similar bactericidal activity as Tdap against pertactin-positive B. pertussis, despite inducing lower anti-aP antigen IgG concentrations than Tdap. Additionally, BPZE1 induced serum bactericidal activity against pertactin-negative B. pertussis, while Tdap did not. Conclusions: High-throughput SBAs were developed and qualified against pertactin-positive and pertactin-negative B. pertussis, enabling measurement of 120 samples per day per analyst. These assays will support clinical development of next-generation pertussis vaccines, including BPZE1. Full article

Background: Avian influenza is a critical zoonotic infection threatening both the poultry industry and global public health. While traditional intramuscular vaccines elicit systemic immunity, they often fail to provide robust local protection at mucosal surfaces. There is thus significant interest in the development of mucosal avian influenza vaccines administered via the intranasal route. However, in humans, this approach is significantly hampered by the availability of safe and effective adjuvants. Methods: This study investigated the immunogenicity of a modified recombinant influenza A/H5 hemagglutinin (rHA/H5-modif) formulated with Novochizol, a novel chitosan-derived delivery system, administered intranasally to laboratory animals. Results: Our results demonstrate that mucosal immunization with the rHA/H5-modif/Novochizol complex induces potent humoral (IgG and IgA) and cell-mediated immune responses. Crucially, the formulation provided 100% survival in mice following a lethal challenge with highly pathogenic avian influenza A/H5. Conclusions: These findings position the rHA/H5-modif/Novochizol complex as a promising candidate for next-generation mucosal vaccines, in particular against highly pathogenic avian influenza A/H5 subtype. Full article

Vaccination represents the cornerstone of Newcastle disease control. Nanotechnology offers a promising approach to improve the effectiveness of DNA vaccines, supporting their use as an alternative to conventional platforms. Herein, the Avian Orthoavulavirus 1 (AOAV-1) fusion (F) gene was cloned into a DNA expression plasmid (pDNA). After validating the constructed pDNA-F and confirming robust intracellular protein expression in vitro, three polymeric nanoparticles (NPs)-based formulations were generated using Chitosan (Cs), poly(lactic-co-glycolic) (PLGA), and poly(amidoamine) (PAMAM)-Dendrimers. Physicochemical characterization, stability assessment, and in vitro release analysis confirmed nanoparticle formation and effective DNA incorporation. In vivo experiments were conducted to comparatively evaluate the immunogenicity, particularly the immune priming capacity, and protective efficacy of nanoparticle-based formulations and naked pDNA-F, all tested in parallel at standardized pDNA doses via intranasal (IN) and intramuscular routes. PAMAM-Dendrimers-pDNA-F IM group demonstrated superior efficacy, with 100% survival, the highest post-challenge anamnestic antibody titers, and a pronounced reduction in viral RNA shedding. PLGA-NPs-pDNA-F IN group demonstrated enhanced efficacy, with 90% survival. Naked pDNA-F surpassed the Cs-NPs-pDNA-F in both immune priming and clinical protection, with Cs-NPs-pDNA-F exhibiting the lowest overall performance. These findings highlight that DNA vaccine performance depends on both carrier type and administration route, with PAMAM dendrimers and PLGA enhancing efficacy, whereas chitosan demonstrated reduced efficacy under the tested conditions. Full article

Highly pathogenic avian influenza A (H7N9) remains a threat to poultry health and poses a zoonotic risk, highlighting the need for vaccine antigens capable of inducing both systemic and mucosal immunity. In this study, we evaluated X33CLS-H7, a clarified cell-lysate supernatant derived from glycoengineered Pichia pastoris expressing H7 hemagglutinin, in BALB/c mice following intramuscular(i.m.) injection, nebulized inhalation, or intranasal instillation. H7 expression and hemagglutination activity were confirmed by Western blotting and hemagglutination assay, respectively. Serum HA7-specific IgG and IgA responses, hemagglutination inhibition(HI) activity, H7N9 pseudovirus neutralization, bronchoalveolar lavage fluid (BALF) antibodies, and safety readouts were assessed. After two i.m. immunizations, X33CLS-H7 induced the strongest systemic antibody responses, with an HI geometric mean titer of 1:1622 95% CI, 1:1108–1:2348 and a mean log10 NT₅₀ of 4.62. Respiratory immunization also elicited antibody responses. After four doses, high-dose nebulized delivery produced the strongest responses among the respiratory delivery regimens, with serum IgG and IgA titers of 1.02 × 10⁵ and 2.24 × 10³, respectively, an endpoint HI GMT r of 1:457 95% CI, 1:211–1:971, and a mean log10 NT₅₀ of 3.77 compared with 2.02 in saline controls. High-dose nebulized delivery also generated detectable HA7-specific IgG and IgA responses in bronchoalveolar lavage fluid. No overt local or systemic toxicity signals were observed under the tested conditions. These findings indicate that X33CLS-H7 retains HA7-associated antigenicity and can induce systemic and respiratory mucosal antibody responses, supporting its further evaluation as a simplified and scalable H7N9 vaccine antigen candidate. Full article

Influenza A virus (IAV) remains a major global health threat despite available vaccines and antiviral agents, while current therapies are limited by drug resistance and safety concerns. Curcuminoids exhibit antiviral and anti-inflammatory activities but are constrained by poor water solubility and low bioavailability. To address these limitations, we investigated the antiviral and immunomodulatory properties of a water-solubilized curcuminoid nanoparticle formulation (C–S/M) in both in vitro and in vivo models of IAV infection. To evaluate the potential antiviral and anti-inflammatory effects of C–S/M, we performed a cytopathic effect (CPE) reduction assay in triplicate at 0.001 MOI and quantitative real-time PCR (qRT-PCR) targeting viral NS1 transcripts in MDCK cells. C–S/M suppressed viral NS1 vRNA levels in MDCK cells at lower curcuminoid-equivalent concentrations than native curcuminoids and attenuated IAV-induced TNF-α, IL-6, and IL-8 production. Furthermore, in vivo antiviral efficacy was evaluated in female C57BL/6 mice intranasally infected with IAV and treated orally with C–S/M. Survival, lung viral loads, pulmonary cytokine levels, and splenic immune cell phenotypes were analyzed. In IAV-infected mice, oral administration of C–S/M modestly improved survival and significantly reduced lung viral burden and pulmonary proinflammatory cytokine levels. In addition, in vivo C–S/M treatment was associated with recovery of virus-suppressed T-cell immune responses, including increased Th1 and activated CD8⁺ T cells, reduced regulatory T-cell expansion, and restoration of multifunctional CD4⁺ and CD8⁺ T cells. These findings suggest that C–S/M exerts antiviral and immunomodulatory effects in experimental IAV infection and may serve as a potential adjunctive candidate for further investigation against influenza-associated inflammation. Full article

Porcine reproductive and respiratory syndrome virus (PRRSV) remains a major challenge to swine production worldwide. Current vaccines have limited efficacy against genetically diverse PRRSV strains. Therefore, strategies with alternative modes of action—such as antiviral approaches that target conserved virus–host interactions, including viral attachment and entry, rather than relying solely on adaptive immune responses—are needed. We first evaluated the in vitro effect of griffithsin (GRFT), a high-mannose-binding lectin, in the monkey kidney cell line MARC-145. Cells were pre-treated with GRFT (50–200 µg/mL) prior to PRRSV infection, after which cell morphology and viral RNA replication (measured by RT-qPCR) were assessed. Pre-treatment with 100–200 µg/mL GRFT, followed by PRRSV inoculation at a multiplicity of infection of 1 or 10, reduced viral replication in MARC145 cells in a dose-dependent manner, achieving almost 100% inhibition of ORF5 and ORF7 RNA compared with untreated controls (p < 0.0001). We next investigated the in vivo effects of intranasal GRFT administration (7.5 or 15 mg/day) in pigs (n = 56). Pigs treated with 15 mg/day GRFT exhibited significantly reduced (p < 0.05) viremia 2, 4 and 7 days post-challenge, compared with untreated, challenged, and controls (log₁₀ 8.1 ± 0.2 vs. 9.0 ± 0.25, 8.2 ± 0.1 vs. 9.1 ± 0.2, and 8.9 ± 0.2 vs. 9.3 ± 0.2, respectively), along with earlier resolution of fever and a trend toward increased average daily gain over 42 days (p < 0.1). These findings are the first report of GRFT efficacy in pigs and support its potential as an antiviral strategy against PRRSV, alongside existing interventions. Full article

Most infectious pathogens enter the host through mucosal surfaces, yet conventional injectable vaccines primarily induce systemic immunity without eliciting robust secretory immunoglobulin A (SIgA) responses at mucosal sites. The COVID-19 pandemic highlighted this limitation, as intramuscular mRNA vaccines failed to establish durable mucosal immunity in the upper respiratory tract. This review covers recent progress in mucosal vaccine development. We first discuss the organization of the mucosal immune system, focusing on SIgA induction, tissue-resident memory T (${\mathrm{T}}_{\mathrm{RM}}$) cells, and resident memory B (${\mathrm{B}}_{\mathrm{RM}}$) cells. We then examine mucosal adjuvants, from cholera toxin and heat-labile enterotoxin derivatives to stimulator of interferon gene (STING) agonists and a strategy to enhance alum adjuvanticity through neutrophil elastase inhibition. Delivery routes including intranasal, oral, and sublingual administration are reviewed alongside viral vectors, nanoparticles, mRNA-lipid nanoparticles, virus-like particles, and engineered bacterial platforms. The roles of innate immune cells, T helper cell subsets, and the microbiota in shaping vaccine responses are discussed. Finally, we survey licensed mucosal vaccines and the COVID-19 mucosal vaccine pipeline, analyze persistent barriers to clinical translation including the absence of validated mucosal correlates of protection, and outline future directions for thermostable formulations and systems biology-driven vaccine design. Full article

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infects host cells through the interaction between the spike protein receptor-binding domain (RBD) and the human angiotensin-converting enzyme 2 (hACE2) receptor, which is expressed on epithelial cells in various tissues, including the respiratory tract. Therefore, mucosal immunity in the respiratory tract plays a key role in protection against viral infection. Previously, we demonstrated that intranasal administration of antigens (Ags) conjugated with the M cell-targeting peptide Co4B enhances both mucosal and systemic immune responses. That conjugation with human β-defensin 2 (HBD2) increases neutralizing antibody (Ab) responses. Methods: A recombinant antigen conjugate incorporating both Co4B and HBD2 was designed to enhance immunogenicity. Its immunogenicity was evaluated in mice following intranasal immunization. Antigen-specific antibody responses were measured in serum and bronchoalveolar lavage fluid. T-cell responses were evaluated in lungs and spleens. Protective efficacy was assessed using SARS-CoV-2-susceptible hACE2 knock-in mice. Results: Ag-specific Ab levels increased in both serum and bronchoalveolar lavage fluid of mice immunized intranasally with the conjugate. Especially, T-cell responses were significantly enhanced in the lungs and spleens of immunized hACE2 knock-in mice. In challenge experiments, intranasal administration of the conjugate reduced viral load. Moreover, Siglec F was identified as a potential receptor for Co4B, a previously uncharacterized M cell-targeting ligand. Conclusions: A recombinant viral Ag containing Co4B and HBD2 induces virus-specific humoral and cellular immune responses. Although further optimization of the vaccine formulation and administration strategy is needed, this conjugate shows potential as a platform for improving mucosal and systemic immunity. Full article

Background/Objectives: The emergence of SARS-CoV-2 variants and breakthrough infections underscores the need for next-generation vaccines capable of protecting from natural infection and/or preventing virus transmission. Intranasal vaccination offers a promising approach by eliciting local immune responses in the nasal mucosa, the primary site of infection and reservoir for transmissible virus. We evaluated two live-attenuated, respiratory syncytial virus-vectored vaccines in which the RSV F and G surface glycoproteins were replaced with a chimeric SARS-CoV-2 Spike protein from the ancestral USA/WA-1/2020 strain (MV-014-212) or the Delta variant (MV-014-212-delta). Methods: K18-hACE2 mice and LVG Syrian hamsters were vaccinated with a single intranasal dose of MV-014-212 or MV-014-212-delta. Systemic and mucosal immunity were assessed following vaccination, and protection was evaluated following Delta SARS-CoV-2 challenge. In vaccinated hamsters, morbidity, viral shedding, and lung inflammation and injury were also assessed following natural exposure to infected cagemates. Results: A single intranasal dose of either vaccine elicited systemic and mucosal immunity in K18-hACE2 mice, including serum neutralizing antibodies, Spike-specific memory B cells and plasmablasts, and Spike-specific CD8⁺ lung-resident memory T cells. Although MV-014-212-delta vaccination provided the best protection against the Delta variant virus challenge, both vaccines decreased viral loads in nasal discharge, lung, and brain, and reduced weight loss and mortality. In naturally acquired infection studies, vaccinated hamsters exposed to infected cagemates exhibited minimal weight loss, limited viral replication within the nasal mucosa, and attenuated lung pathology. Conclusions: Intranasal RSV-vectored vaccines can elicit broad protective respiratory immunity, suggesting that this platform could be leveraged for other respiratory pathogens. Full article

Pasteurella multocida (P. multocida) is a significant pathogenic bacterium that causes serious disease and death in the yaks of the Tibetan Plateau, and the existing inactivated vaccines are limited by low protection and reactogenicity. Outer membrane vesicles (OMVs) derived from a yak-origin serogroup B P. multocida isolate were evaluated as a potential vaccine candidate in the present study. The purified OMVs were characterized by transmission electron microscopy and nanoparticle tracking analysis, which demonstrated the presence of typical bilayer vesicles ranging from 20 to 300 nm in diameter. Proteomic profiling revealed 1213 proteins, with many of them being immunologically relevant outer membrane-associated proteins like OmpA, OmpH, Omp16, OmpW, TbpA and PlpP. The functional enrichment analysis showed that these proteins were linked to translation, membrane structure, transport, metabolism, and pathways of adaptation of bacteria. In vitro OMVs were effectively taken up by RAW264.7 macrophages and stimulated robust expression of inflammatory mediators, such as TNF-α, IL-1β, IL-6, iNOS and IL-10, which is indicative of strong innate immunostimulatory capacity. OMV immunization induced significant antigen specific humoral responses in mice and yaks in vivo. In mice, intramuscular immunization was effective in giving full protection against P. multocida challenge but not intranasal immunization. Histopathology also indicated less tissue damage in vaccinated animals, especially in the lung and liver. These findings, taken together, prove that yak-derived P. multocida OMVs have high immunogenicity and protection capabilities, which show their potential as a next-generation vaccine platform to tackle P. multocida infection. Full article

Background: Non-typeable Haemophilus influenzae (NTHi) is a major cause of acute respiratory tract infections and chronic airway disease, despite its clinical importance, no licensed vaccine is available, largely due to the extensive genetic and antigenic diversity among circulating isolates. We previously identified conserved outer membrane proteins capable of inducing systemic protection against NTHi. Methods: In this study, we evaluated whether a multi-antigen protein vaccine composed of conserved NTHi antigens (P5 and P26) could protect against pulmonary infection. Transgenic mice expressing human transferrin and factor H were immunized via the intraperitoneal or intranasal route and challenged intranasally with a clinical NTHi isolate. Bacterial clearance, antigen-specific mucosal and systemic antibody responses, and recruitment of innate immune cells to the airways were assessed. Results: Both immunization routes significantly reduced bacterial loads compared with controls. Vaccination induced robust mucosal and systemic IgG and IgA responses and enhanced early recruitment of macrophages, monocytes, dendritic cells, and neutrophils to the airways. Intranasal immunization elicited strong mucosal antibody responses and was associated with improved local bacterial clearance. Conclusions: These findings demonstrate that multi-antigen vaccines targeting conserved NTHi proteins can elicit effective mucosal and systemic immunity and represent promising candidates for the prevention against NTHi respiratory infections. Full article

Background/Objectives: Bordetella bronchiseptica is a Gram-negative bacterium that, either acting alone or in concert with other bacterial or viral pathogens, is a major cause of the canine infectious respiratory disease (CIRD) complex in dogs. Most currently available vaccines are given intranasally or orally and, whilst providing satisfactory reduction in disease severity, can be difficult to use especially in aggressive or anxious dogs. Whilst a small number of injectable B. bronchiseptica vaccines have been developed, little is known about their characteristics with regard to the age at first vaccination, the onset of immunity, duration of immunity, induction of antibody responses, concurrent use with the core vaccines used in most dogs, efficacy in the face of maternally derived antibodies (MDAs) or existing immunity and safety in pregnant animals. Here we describe the development of a safe and efficacious injectable B. bronchiseptica vaccine that utilises a novel process to purify fimbriae. Methods: The fimbrial antigen was formulated with a vitamin E-based oil-in-water adjuvant known to be safe in dogs (Nobivac^® Respira Bb). To evaluate dose response, thirty-nine naïve 5–6-week-old Beagle puppies were allocated to four groups and vaccinated subcutaneously with Nobivac^® Respira Bb at 69 U, 25 U, and 7 U (with a booster at two weeks). All groups were challenged with B. bronchiseptica two weeks after the booster. To evaluate the onset of immunity at 5–6 weeks of age, twenty-one naïve Beagle dogs were split into two groups: group 1 received Nobivac Respira Bb (88 U/dose) plus Nobivac DHPPi and Nobivac L4; group 2 received DHPPi and L4 only. Both groups were challenged with B. bronchiseptica two weeks after the second vaccination. Safety in pregnancy was evaluated by vaccinating pregnant dams and monitoring whelping outcomes and puppy health. Protection in puppies with maternally derived antibodies (MDAs) was studied in 28 pups (11 MDA-negative and 17 MDA-positive from vaccinated and unvaccinated dams). Pups were vaccinated at 5–6 weeks; one group remained unvaccinated to monitor MDA kinetics. All puppies were challenged with B. bronchiseptica at 19 weeks, after MDAs became undetectable. Serology was monitored throughout; daily clinical observations and nasal swabs post-challenge assessed protection and bacterial shedding. Results: Nobivac Respira Bb (MSD Animal Health), was safe for use in 5–6-week-old puppies alongside other Nobivac core canine vaccines without vaccine interference. The vaccine has an onset of immunity of two weeks and significantly reduces both the clinical signs of B. bronchiseptica-induced disease and bacterial excretion into the environment. Furthermore, the vaccine is equally efficacious in puppies with maternally derived antibodies derived from vaccinated dams and can be used safely in pregnant bitches. Conclusions: This vaccine represents a convenient, safe and efficacious alternative to vaccines delivered via the oral or intranasal routes and is a positive addition to the range of vaccines targeted at reducing disease induced by B. bronchiseptica. Full article

Klebsiella pneumoniae poses a severe global health threat due to its extensive antibiotic resistance. However, to date, no vaccine against this pathogen has been approved for clinical use worldwide. Although self-assembling nanocarriers present distinct advantages for vaccine design, their ability to effectively load polysaccharide antigens and further elicit mucosal immunity remains unclear. Here, we developed a modular, self-assembling nanovaccine (CNP-OPS_KpO1) against K. pneumoniae by loading of K. pneumoniae O1 polysaccharide antigen onto a cholera toxin B subunit (CTB)-based nanoparticle (CNP). After determining the safety of the vaccine via intranasal immunization, we further evaluated its immune efficacy. CNP-OPS_KpO1 elicited stronger systemic IgG and mucosal sIgA responses than non-nanoparticulate controls. In a non-lethal pulmonary infection model, CNP-OPS_KpO1 vaccination reduced lung bacterial burden by over 5 logs compared to controls, achieving near-complete bacterial clearance. Histopathological analysis further confirmed minimal lung damage in vaccinated animals. In addition, in a lethal pulmonary challenge model, it conferred 90% survival, whereas all mice in the antigen-alone control group died within 4 days. Our work not only provides a safe, effective, and adjuvant-free candidate vaccine against K. pneumoniae but also advances a versatile platform for developing broad-spectrum mucosal vaccines against other pathogens. Full article

Background: Respiratory syncytial virus (RSV) causes severe lung infections in infants and the elderly. The conserved central domain (CCD) of the RSV G protein is a key antigenic fragment for inducing protective antibodies. In this study, we used the hepatitis B surface antigen (HBsAg) as a platform to present this RSV G CCD fragment. Methods: We first sequenced and compared several HBsAg genotypes from clinical samples and selected one as an expression candidate for further development. The RSV G CCD was then inserted into the selected candidate to generate a recombinant expression construct. Subviral particles (SVPs) were produced using both CHO cells and yeast expression systems. Particle assembly was examined using electron microscopy. Finally, the safety and immunogenicity of the recombinant vaccine were evaluated in mice. Results: We successfully identified HBsAg38 as a potential recombinant vaccine expression candidate due to its abundant expression and secretion. The RSV G CCD fragment was inserted into the candidate and efficiently expressed in both CHO cells and yeast. The expressed protein was effectively secreted and formed uniform, spherical particles. The resulting vaccine candidate was safe for mice, causing no detectable weight loss or organ damage. Immunization with the recombinant SVPs elicited antibody responses against both HBsAg and the RSV G CCD. Upon intranasal RSV challenge, vaccinated mice exhibited markedly reduced RSV F protein and mRNA levels in lung tissues compared to PBS controls, with the yeast-derived SVP group showing the most pronounced reduction. Histopathological analysis further revealed that immunized mice had significantly less alveolar destruction and inflammatory cell infiltration than the control group, confirming that the vaccine conferred effective protection against RSV-induced lung pathology. Conclusions: We successfully developed a novel antigen-displaying HBsAg platform for generating vaccines targeting multiple pathogens. The RSV G CCD-expressing HBsAg induced a strong antibody response and provided effective protection against RSV infection. This platform offers a promising new approach for the development of next-generation vaccines. Full article

Background/Objectives: Hand, foot, and mouth disease (HFMD) is a major public health concern primarily caused by human enterovirus A71 (EV-A71), coxsackievirus A16 (CVA16), coxsackievirus A6 (CVA6), and certain coxsackievirus B serotypes. Currently available EV-A71 vaccines lack cross-protective efficacy against other serotypes, highlighting the urgent need for multivalent and broadly effective enterovirus vaccines. Methods: Immunoinformatics approaches were used to predict highly immunogenic B-cell and T-cell epitopes, which were assembled to construct a novel multivalent epitope vaccine, rCV-A3V, followed by in silico validation. Recombinant protein expression was confirmed by Western blotting and immunofluorescence assays. The immunogenicity was evaluated in Balb/c mice following intranasal immunization. Results: A preliminary safety evaluation demonstrated that the rCV-A3V vaccine was well tolerated in the mouse model, with no abnormal changes in body weight observed after immunization. In addition, the target protein was successfully expressed. Intranasal immunization induced a strong Th1-biased immune response, robust serum neutralizing and IgG antibody responses, and pronounced mucosal immunity, including elevated sIgA and IgG levels in nasal lavage fluid, sIgA in feces, and substantial sIgA responses in milk. Dominant epitope peptides were also identified. Conclusions: The intranasal live attenuated rCV-A3V vaccine successfully induced humoral, mucosal, and cellular immune responses against EV-A71, CVA16, CVA6, and CVB3, demonstrating broad immunogenicity. These findings provide experimental evidence supporting its potential as a candidate vaccine for HFMD. Full article