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37 pages, 12756 KB  
Review
Advances in Antiviral Drug Development Targeting Enteroviruses: From Viral Proteins to Host Factors
by Jiaying Lu, Congyi Li, Wenzhe Cui, Yining Du, Jiayi Geng and Wenyan Zhang
Viruses 2026, 18(4), 476; https://doi.org/10.3390/v18040476 (registering DOI) - 18 Apr 2026
Abstract
Enteroviruses represent important human pathogens, posing a substantial disease burden, particularly in children under 5 years of age. Enteroviruses are the primary causative agents of hand-foot-and-mouth disease (HFMD) and are strongly associated with acute flaccid myelitis (AFM), with severe cases potentially resulting in [...] Read more.
Enteroviruses represent important human pathogens, posing a substantial disease burden, particularly in children under 5 years of age. Enteroviruses are the primary causative agents of hand-foot-and-mouth disease (HFMD) and are strongly associated with acute flaccid myelitis (AFM), with severe cases potentially resulting in significant neurological complications. Inactivated vaccines against EV-A71 based on the C4 genotype are currently available. However, there are no licensed direct antiviral agents for severe cases. By focusing on viral proteins and host factors, researchers have made great strides in the creation of antiviral medications that target enteroviruses. However, several viral candidates failed to progress in clinical development due to limited efficacy or side effects. This review discusses key findings in enterovirus antiviral research, analyzes the advantages and limitations of each drug target, and highlights knowledge gaps that need to be addressed to advance further development in this field. Full article
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28 pages, 5479 KB  
Review
γ-Cyclodextrin Metal–Organic Frameworks for Drug Delivery: Current Advances in Synthesis, Activation, Encapsulation and Applications
by Lubna Y. Ashri
Pharmaceutics 2026, 18(4), 502; https://doi.org/10.3390/pharmaceutics18040502 (registering DOI) - 18 Apr 2026
Abstract
Metal–organic frameworks (MOFs) are a versatile class of hybrid crystalline materials that have emerged as promising candidates for a broad range of applications. γ-cyclodextrin MOFs (γ-CD-MOFs) represent an innovative subgroup of MOFs constructed from “edible” γ-CD ligands coordinated with biocompatible metal ions to [...] Read more.
Metal–organic frameworks (MOFs) are a versatile class of hybrid crystalline materials that have emerged as promising candidates for a broad range of applications. γ-cyclodextrin MOFs (γ-CD-MOFs) represent an innovative subgroup of MOFs constructed from “edible” γ-CD ligands coordinated with biocompatible metal ions to form an extended porous structure. Owing to their unique characteristics such as their “green” origin, biodegradability, and biocompatibility they became a promising platform for drug delivery applications. Structurally, γ-CD-MOF possess a body-centered cubic structure with dual-mode porosity, enabling the simultaneous encapsulation of hydrophilic and hydrophobic drugs. Such structural features contribute to high loading capacity, tunable release behavior, and enhanced stability of incorporated drugs. In this review, we comprehensively discuss the structural features of γ-CD-MOF, synthesis strategies, crystals size and morphology control, activation and drying techniques, and drug encapsulation approaches. We further address computational and simulation approaches used to predict and optimize drug-framework interactions, as well as post- synthetic modifications aimed at enhancing stability and functionality. The diverse pharmaceutical applications of γ-CD-MOFs are examined, including the delivery of small molecules, macromolecules, multi-drug systems, and emerging pulmonary formulations. Additionally, we examine biocompatibility and safety considerations and current limitations related to aqueous stability, industrial-scale production, and reproducibility. Finally, this review highlights recent progress and underlines future perspectives, emphasizing innovations such as fast drug-loaded MOF formation via spray-drying, co-delivery strategies, and vaccine-oriented formulations. Together, these insights highlight the potential of γ-CD-MOFs to shape the next generation of multifunctional drug delivery systems across interdisciplinary fields. Full article
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18 pages, 8115 KB  
Article
First Complete Genome Sequencing of a Pigeonpox Virus Strain from Mainland China and Preliminary Evaluation of Its Attenuated Potential
by Yifan Zhu, Baolichen Zhang, Zhongshu Ji, Jingliang Su, Jianyu Chang and Kai Fan
Vet. Sci. 2026, 13(4), 393; https://doi.org/10.3390/vetsci13040393 - 17 Apr 2026
Abstract
Pigeonpox is a significant infectious disease caused by Pigeonpox virus (PPV), which severely impacts the pigeon industry. Current control methods primarily rely on heterologous vaccines, such as those derived from avian poxviruses, but their protection is limited, creating an urgent need for the [...] Read more.
Pigeonpox is a significant infectious disease caused by Pigeonpox virus (PPV), which severely impacts the pigeon industry. Current control methods primarily rely on heterologous vaccines, such as those derived from avian poxviruses, but their protection is limited, creating an urgent need for the development of a specific vaccine. In this study, 720 samples collected from several regions of China between 2022 and 2023 were tested for PPV, followed by virus isolation, identification, and genetic evolutionary analysis. Based on these findings, complete genome sequencing and attenuation of the representative BJ-02 isolate were conducted, and the potential of this strain as a candidate for an attenuated vaccine was preliminarily evaluated. The survey showed PCR positive rates of 9.05%, 16.11%, and 12.50% in samples from Beijing, Guangdong, and Hainan, respectively. Six viral strains were isolated, all of which produced typical lesions on chorioallantoic membranes (CAM) and chicken embryo fibroblasts (CEF). Phylogenetic analysis based on the P4b gene revealed that the six viruses clustered within the same evolutionary branch, closely related to PPV and penguinpox virus strains from South Africa, India, and Taiwan, China. Complete genome sequencing of the BJ-02 strain showed its genomic structure to be similar to that of other fowlpox viruses, with some differences. After serial passage in CAM, PEF and CEF, the BJ-02 SD55 high-passage strain adapted well to in vitro culture, exhibited significantly reduced pathogenicity in chicken embryos and pigeons, and showed no reversion to virulence after five consecutive back-passages. Animal immunization tests demonstrated that the BJ-02 SD55 suspected attenuated strain induced specific antibodies and provided 100% protection against challenge with the virulent strain. In conclusion, PPV is widely prevalent in China. The BJ-02 strain, successfully isolated and attenuated through serial passage, demonstrates excellent immunogenicity and high safety, making it a promising candidate for a specific pigeonpox vaccine. Additionally, the complete genome characterization of BJ-02 contributes to the avian poxvirus genome database and provides critical data to support research on viral pathogenesis and the development of viral vector vaccines for avian and potentially mammalian species. Full article
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10 pages, 899 KB  
Article
Multi-Antigen Protein Vaccine Confers Protection in a Murine Model Against Intranasal Haemophilus influenzae Challenge
by Nouria Belkacem, Ala-Eddine Deghmane and Muhamed-Kheir Taha
Vaccines 2026, 14(4), 357; https://doi.org/10.3390/vaccines14040357 - 17 Apr 2026
Abstract
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 [...] Read more.
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
(This article belongs to the Section Vaccines and Public Health)
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15 pages, 1122 KB  
Article
Gene Factors and Serotypes Related to Polysaccharide and Protein-Based Candidate Vaccines Among Streptococcus agalactiae Isolates
by Vasil S. Boyanov, Alexandra S. Alexandrova and Raina T. Gergova
Curr. Issues Mol. Biol. 2026, 48(4), 399; https://doi.org/10.3390/cimb48040399 - 14 Apr 2026
Viewed by 119
Abstract
A new strategy to reduce the morbidity and mortality associated with invasive Streptococcus agalactiae (Streptococcus group B, GBS) diseases encompasses the development of vaccines. Candidate vaccines at different stages of clinical trials have been developed on capsular polysaccharides or protein antigens. We studied [...] Read more.
A new strategy to reduce the morbidity and mortality associated with invasive Streptococcus agalactiae (Streptococcus group B, GBS) diseases encompasses the development of vaccines. Candidate vaccines at different stages of clinical trials have been developed on capsular polysaccharides or protein antigens. We studied 328 GBS isolates identified using routine microbiological tests, latex-agglutination, and PCRs. The samples were categorised into two main groups: vaginal (69.2%) and extra-vaginal (30.8%). The molecular serotyping and target gene factors were determined using singleplex or multiplex PCRs. The most common serotypes identified were Ia (24.7%), V (22.0%), and III (18.9%). Serotypes I–V constituted a total of 89.0%. The non-typeable were 9.8%. The frequency of genes included in the recombinant GBS-NN (rib + bca) and GBS-NN2 (epsilon + alp2/3) vaccines were 54.3% and 40.8%. We noted a significant prevalence in the distribution of serotypes II, III, and non-typeable in GBS-NN, whereas serotypes Ia and IV were predominant in GBS-NN2. The serotype prevalence identified in our research was consistent with the data from our region and confirmed the predominance of the six main serotypes included in the hexavalent conjugated vaccine. We highlighted the importance of the combined administration of both protein vaccines, ensuring optimal vaccine coverage. Full article
(This article belongs to the Special Issue Molecular Biology in Drug Design and Precision Therapy, 2nd Edition)
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21 pages, 3661 KB  
Article
Recombinant Attenuated Salmonella Enteritidis Vector Enhances the Immunogenicity of Clostridium perfringens EntB Antigen for Effective Prevention of Avian Necrotic Enteritis
by Wenjing Li, Yu-An Li, Xiaolong Liu, Haiping Xie, Jingyi Zhao, Yi Feng and Huoying Shi
Biomolecules 2026, 16(4), 575; https://doi.org/10.3390/biom16040575 - 13 Apr 2026
Viewed by 182
Abstract
Necrotizing enteritis (NE) is an important intestinal disease threatening the poultry farming industry, and the ban on antibiotic growth promoters has created an urgent demand for safe and effective NE vaccines. Recombinant attenuated Salmonella vectors (RASVs) administered orally can induce mucosal immune responses [...] Read more.
Necrotizing enteritis (NE) is an important intestinal disease threatening the poultry farming industry, and the ban on antibiotic growth promoters has created an urgent demand for safe and effective NE vaccines. Recombinant attenuated Salmonella vectors (RASVs) administered orally can induce mucosal immune responses against delivered antigens, thus showing great potential to elicit protective immunity against NE. The EntB protein is a newly discovered putative enterotoxin of Clostridium perfringens (C. perfringens). Bioinformatic predictions in this study revealed that EntB contains nineteen potential antigenic epitopes, two functional domains (NlpC and YgiM), and interacts with ten proteins, supporting its potential as a target antigen for NE vaccines. To optimize the immunogenicity of EntB-based vaccines, we constructed a novel recombinant attenuated Salmonella Enteritidis (S. Enteritidis) vector rSC0169 harboring a rhamnose-regulated delayed attenuation system, which was then used to deliver EntB to generate the recombinant strain rSC0169(pS-EntB). This system enhanced the immunogenicity of the Salmonella vector rSC0169 and further elicited robust mucosal immune responses against EntB, as well as humoral and cellular immune responses. Compared with the control strain rSC0169(pS0018), rSC0169(pS-EntB) candidate vaccine strain significantly alleviated NE symptoms, increased the intestinal villus height/crypt depth (VH/CD) ratio, upregulated tight junction protein expression, and reduced excessive pro-inflammatory cytokine production. In conclusion, this study provides a promising NE candidate vaccine and offers a valuable strategy for developing vaccines against other intestinal bacterial diseases. Full article
(This article belongs to the Section Biomacromolecules: Proteins, Nucleic Acids and Carbohydrates)
30 pages, 4465 KB  
Article
Unraveling the Potential of Giardia Extracellular Vesicles as a Vaccine Candidate
by Clarissa Faria, Sandra Jesus, Bárbara Ferreira, Ágata Lourenço, Ana Isabel Sebastião, Daniela Mateus, Bruno M. Neves, Olga Borges, Maria Teresa Cruz and Maria do Céu Sousa
Pharmaceutics 2026, 18(4), 461; https://doi.org/10.3390/pharmaceutics18040461 - 9 Apr 2026
Viewed by 286
Abstract
Objectives: This study aimed to investigated the role of Giardia extracellular vesicles (EVs) in intercellular communication and to evaluated their potential as vaccine candidates. Methods: The immunomodulatory effects of Giardia EVs were assessed in mouse macrophages and human monocyte-derived dendritic cells (Mo-DCs), [...] Read more.
Objectives: This study aimed to investigated the role of Giardia extracellular vesicles (EVs) in intercellular communication and to evaluated their potential as vaccine candidates. Methods: The immunomodulatory effects of Giardia EVs were assessed in mouse macrophages and human monocyte-derived dendritic cells (Mo-DCs), with a particular focus on key inflammatory signaling pathways. In vivo immunogenicity was evaluated following EV administration, and the antigenic composition of EV cargo was characterized by proteomic analysis. Results: Giardia EVs activated pro-inflammatory signaling pathways in mouse macrphages, including SAPK/JNK, ERK1/2, and NF-κB. This activation was associated with IκB-α degradation and nuclear translocation of p65. Furthermore, EV stimulation significantly upregulated the expression of pro-inflammatory genes, including Il1β, Il6, Il4, Ptgs2, Nos2, and Tnf, with log2 fold changes ranging from 3.9 to 15.8. Consistently, EVs increased iNOS protein expression (28–45%) and nitrite production (9.6–12.3-fold). In human Mo-DCs, Giardia EVs promoted cellular maturation, as evidenced by increased expression of MHC-II, CD80, and CD86, and enhanced T-cell proliferation with a Th1-skewed profile. In vivo immunization induced antigen-specific antibody responses, with IgG subclass distribution indicative of a balanced Th1/Th2 response. Proteomic analysis identified immunoreactive EV-associated proteins, including elongation factor 1-alpha, α-7.3 giardin, tubulin, and variant surface proteins (VSPs), which are well-established antigens in Giardia infection, with prominent bands observed at approximately 22 kDa and 50 kDa. Conclusions: Collectively, these findings demonstrate that Giardia EVs modulate innate immune responses in vitro, elicit antigen-specific humoral immunity in vivo, and contain conserved immunogenic proteins. These properties support their potential as a promising cell-free vaccine platform against giardiasis. Full article
(This article belongs to the Special Issue Next-Generation for mRNA Vaccine Delivery)
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18 pages, 2755 KB  
Article
Three-Component Subunit Vaccine Induces Protective Immunity Against Mycoplasma pneumoniae in Mice
by Han Wang, Tiantian Wang, Zhuoran Hou, Ruixi Liu, Qianhui Liu, Zhu Zhou, Bin Zhang, Xuchen Hou, Lu Li, Jun Wu and Bo Liu
Vaccines 2026, 14(4), 330; https://doi.org/10.3390/vaccines14040330 - 7 Apr 2026
Viewed by 395
Abstract
Background: Mycoplasma pneumoniae (MP) is a major cause of respiratory tract infections in children and adolescents. Currently, there is no licensed vaccine, underscoring the urgent need for the development of safe and effective vaccines. Objective: The aim of this study is to develop [...] Read more.
Background: Mycoplasma pneumoniae (MP) is a major cause of respiratory tract infections in children and adolescents. Currently, there is no licensed vaccine, underscoring the urgent need for the development of safe and effective vaccines. Objective: The aim of this study is to develop a recombinant subunit vaccine candidate incorporating three antigens: the P1 protein, the P40/90 complex, and a detoxified mutant of community-acquired respiratory distress syndrome toxin. The protective efficacy of this vaccine candidate was also evaluated. Methods: Target genes were codon-optimized for expression in E. coli, and the recombinant proteins were successfully expressed and purified. The low-toxicity CARDS toxin mutant was screened based on TNF-α secretion levels in stimulated RAW264.7 cells. A three-component vaccine composed of P1, P40/90, and the mutant CARDS toxin was formulated and adjuvanted with either Al(OH)3 alone or in combination with CpG. Mice were immunized, and immunogenicity was assessed by measuring antigen-specific IgG antibody titers. Protective efficacy was evaluated following challenge by analyzing lung histopathology, bacterial load, and inflammatory cytokine levels. Results: Seven high-purity recombinant proteins were successfully produced, including P1, the P40/90 complex, wild-type CARDS toxin, and four CARDS toxin mutants (E132A, E132Q, H36A, R10A). The E132A mutant was selected due to its significantly reduced toxicity while retaining immunogenicity. The three-component vaccine effectively elicited antibody responses against each of the included antigens. After three immunizations, IgG antibody titers in all groups reached approximately 104. Immunized mice showed markedly reduced pulmonary pathology scores (control group: 2 or 2.67; immunized groups: 1.67, 1.33, and 0) and significantly decreased bacterial loads in lung tissue (control: 30.11 ± 10.40 cp/μL; immunized groups: 20.72 ± 4.37 cp/μL and 8.51 ± 8.32 cp/μL). Furthermore, the group receiving the alum + CpG adjuvant exhibited approximately a 10-fold higher antibody response compared with the alum-only group, indicating enhanced protective efficacy. Conclusions: The three-component candidate vaccine, MPtriV, adjuvanted with Al(OH)3 + CpG, demonstrates promising immunogenicity, safety, and protective efficacy against Mycoplasma pneumoniae infection, providing a viable strategy and experimental foundation for the development of MP subunit vaccines. Full article
(This article belongs to the Section Vaccine Advancement, Efficacy and Safety)
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10 pages, 394 KB  
Article
Evaluation of Latent Tuberculosis Infection Risk in Liver Transplant Recipients
by Miraç Öz Kahya, Serhat Erol, Dilara Kış Gökçecik, Elvan Onur Kırımker, Güle Çınar, Akın Fırat Kocaay, Deniz Balcı and Özlem Özdemir Kumbasar
J. Clin. Med. 2026, 15(7), 2803; https://doi.org/10.3390/jcm15072803 - 7 Apr 2026
Viewed by 233
Abstract
Background/Objectives: Tuberculosis remains one of the preventable causes of mortality among liver transplant recipients. The prevalence of tuberculosis in solid organ transplant recipients is higher than in the general population. The aim of this study was to evaluate the incidence of latent [...] Read more.
Background/Objectives: Tuberculosis remains one of the preventable causes of mortality among liver transplant recipients. The prevalence of tuberculosis in solid organ transplant recipients is higher than in the general population. The aim of this study was to evaluate the incidence of latent tuberculosis infection (LTBI) and active tuberculosis after liver transplantation. Methods: This is a retrospective, single-center, case–control study. Adult liver transplant candidates who were evaluated between 1 January 2016 and 31 December 2022 were retrospectively assessed. Patients with pre-transplant tuberculin skin test (TST) and/or interferon-gamma release assay (IGRA) results who underwent transplantation were included in this study. Results: A total of 111 liver transplant recipients with available IGRA and/or TST results were included; 70 were men (63.1%) and 41 were women (36.9%), with a mean age of 53.5 ± 11.3 years. Demographic, clinical, and laboratory characteristics were evaluated. The most common indication for liver transplantation was viral hepatitis (33.3%), followed by cryptogenic cirrhosis (19.8%) and hepatocellular carcinoma (10.8%). All patients had a Bacillus Calmette–Guérin (BCG) vaccination scar. Ten patients received grafts from deceased donors, while 101 underwent living-donor liver transplantation. No patient received LTBI treatment before transplantation, whereas LTBI treatment was initiated in four patients after transplantation. None of the patients had a diagnosis of active tuberculosis prior to transplantation. Thoracic computed tomography revealed findings compatible with tuberculosis sequelae in 11 patients (9.9%). During a median follow-up period of 49 [27–64] months after transplantation, no cases of active tuberculosis were observed among patients with positive TST and/or IGRA results. Patients were divided into two groups according to their TST and IGRA results. Group 1 consisted of patients with IGRA positivity and/or a TST ≥ 5 mm, while Group 2 included patients with a TST < 5 mm and negative IGRA results. The only statistically significant difference between the groups was the administration of LTBI treatment (p = 0.027); four patients in Group 1 received LTBI therapy. None of these patients were able to continue prophylaxis due to treatment-related adverse effects. Conclusions: Prophylaxis with hepatotoxic agents poses a substantial risk in liver transplant candidates. Since the hepatotoxicity may cause early cessation of LTBI treatment, the risk–benefit ratio of post-transplant LTBI therapy should be carefully assessed. In situations where LTBI treatment is deferred, close clinical monitoring is strongly recommended. Full article
(This article belongs to the Section Respiratory Medicine)
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22 pages, 7317 KB  
Article
Peptide Coacervates Promote Cytosolic Delivery of STING Agonists for Cancer Immunotherapy
by Wenlv Zheng, Wei Tang, Jianzheng Wang, Yurong Li, Shengnan Wang, Dan Wu, Xiaoquan Wang and Junmin Quan
Vaccines 2026, 14(4), 329; https://doi.org/10.3390/vaccines14040329 - 7 Apr 2026
Viewed by 590
Abstract
Background/Objectives: Cyclic dinucleotide stimulator of interferon genes (STING) agonists have emerged as potential agents in cancer immunotherapy, but their clinical applications are limited by relatively poor pharmacokinetic properties. Methods: A luciferase reporter assay was employed to screen delivery peptides capable of [...] Read more.
Background/Objectives: Cyclic dinucleotide stimulator of interferon genes (STING) agonists have emerged as potential agents in cancer immunotherapy, but their clinical applications are limited by relatively poor pharmacokinetic properties. Methods: A luciferase reporter assay was employed to screen delivery peptides capable of promoting cellular activating effect of cyclic dinucleotide STING agonists. The potent candidates were further confirmed by enzyme-linked immunosorbent assay (ELISA), real-time quantitative PCR (qPCR) and Western blotting analysis. Colon and melanoma cancer mouse models were used to examine the antitumor efficacy of the delivery peptides with cyclic GMP–AMP (cGAMP) as a therapeutic agents or vaccine adjuvant. Results: We identify a class of STING agonist delivery peptides that efficiently facilitate cytosolic delivery of cyclic dinucleotide STING agonists and promote STING activation by forming peptide coacervates. Intratumoral administration of Sti3-4A and cGAMP effectively suppressed tumor growth and promoted antitumor immune response. Furthermore, the conjugation of tumor-specific antigen peptides with Sti3-4A promoted cytosolic co-delivery of antigen peptides and cGAMP, thus significantly boosting APC maturation, antigen cross-presentation, and T cell responses to peptide antigens. Prophylactic and therapeutic immunization with the conjugated peptides and cGAMP inhibited tumor growth in multiple murine tumor models. Conclusion: These findings establish STING agonist delivery peptides as a versatile platform for cancer immunotherapy. Full article
(This article belongs to the Section Vaccination Against Cancer and Chronic Diseases)
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23 pages, 1793 KB  
Review
Tea Polyphenols in the COVID-19 Era: Mechanistic Insights and Translational Challenges
by Harrison Chang, Chi-Sheng Wu, Ting-Yu Yeh and Wen-Chin Ko
Curr. Issues Mol. Biol. 2026, 48(4), 379; https://doi.org/10.3390/cimb48040379 - 5 Apr 2026
Viewed by 398
Abstract
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has driven the global COVID-19 pandemic, imposing a tremendous burden on public health. As the virus continually evolves through rapid mutations, the pandemic has transitioned into a prolonged endemic phase. Despite the development of novel [...] Read more.
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has driven the global COVID-19 pandemic, imposing a tremendous burden on public health. As the virus continually evolves through rapid mutations, the pandemic has transitioned into a prolonged endemic phase. Despite the development of novel drugs and vaccines, clinical outcomes remain suboptimal for vulnerable populations, including the elderly and those with comorbidities or compromised immunity. Tea polyphenols, a class of structurally diverse and bioactive nutraceuticals, may modulate viral entry, replication, and host inflammatory pathways implicated in disease progression through pleiotropic effects on viral attachment, membrane fusion, intracellular replication, and proteolytic processing. Here, we provide an updated chemo-biological perspective on the antiviral and immunomodulatory mechanisms of tea polyphenols against SARS-CoV-2. Current evidence highlights their potential to serve as promising candidates for further mechanistic and translational investigation as adjunctive strategies and nutraceuticals for COVID-19 management. Importantly, no large-scale randomized controlled trials have yet demonstrated clinical benefit of tea polyphenols in COVID-19. Full article
(This article belongs to the Special Issue Advances in Phytochemicals: Biological Activities and Applications)
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17 pages, 5018 KB  
Article
A Rabies Virus Glycoprotein Subunit Vaccine Produced in Pichia pastoris Induces Neutralizing Antibodies in Mice
by Ye Yang, Ruo Mo, Zhuoran Hou, Han Wang, Peng Sun, Ruixi Liu, Tiantian Wang, Bin Zhang, Xuchen Hou, Yongkun Zhao, Jun Wu and Bo Liu
Vaccines 2026, 14(4), 322; https://doi.org/10.3390/vaccines14040322 - 4 Apr 2026
Viewed by 482
Abstract
Background: Rabies is a highly fatal zoonotic disease that causes approximately 59,000 human deaths worldwide each year. Current inactivated rabies vaccines require multiple doses and are associated with high costs. The full-length rabies virus glycoprotein (RVG), a membrane protein, exhibits substantial instability [...] Read more.
Background: Rabies is a highly fatal zoonotic disease that causes approximately 59,000 human deaths worldwide each year. Current inactivated rabies vaccines require multiple doses and are associated with high costs. The full-length rabies virus glycoprotein (RVG), a membrane protein, exhibits substantial instability in its trimeric structure during recombinant expression. This instability makes it difficult to obtain high-purity, correctly folded antigens. Objectives: This study focuses on the preparation of a full-length recombinant RVG subunit vaccine candidate expressed in a glycoengineered Pichia pastoris system with mammalian-like glycosylation. Methods: The full-length RVG gene (including the transmembrane domain and cytoplasmic tail) from the Challenge Virus Standard-11 (CVS-11) strain was codon-optimized and inserted into the pPICZαA vector to construct the recombinant expression plasmid pPICZαA-RVG. The plasmid was transformed into glycoengineered Pichia pastoris X33-7 (low-mannose type) by electroporation for inducible expression. The target protein was purified by nickel affinity chromatography, anion-exchange chromatography, and Superdex-200 size-exclusion chromatography. The structural characteristics of the purified protein were analyzed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The purified antigen was formulated with the adjuvants AS03 or MF59. BALB/c mice (n = 5 per group) were immunized intramuscularly following a four-dose schedule (days 0, 7, 14, and 28). Antigen-specific IgG antibody titers were measured by ELISA, and neutralizing antibody titers were determined using the rapid fluorescent focus inhibition test (RFFIT). Results: Glycoengineered Pichia pastoris yeast strains expressing wild-type RVG (RVG-WT) or a mutant variant (RVG-M6: R84S, R199S, H270P, R279S, K300S, and R463S) were successfully constructed. The purified RVG antigen formed nanoparticles with an average particle size of approximately 75 nm. Immunized mice generated robust RVG-specific IgG responses, with titers reaching approximately 6.31 × 105 for RVG-WT after the fourth immunization, compared to 3.16 × 103 for RVG-M6 and 5.62 × 103 for the RVG-WT-PEG control. Two weeks after the fourth immunization, RVG-WT formulated with AS03 or MF59 induced significant neutralizing antibody responses compared with the control group (p < 0.0001 and p < 0.01, respectively). The neutralizing antibody titers reached 1:79.43 in the AS03 group and 1:33.11 in the MF59 group, whereas the WT-PEG + AS03 control group showed a low titer of 1:3.72. In contrast, RVG-M6 formulated with MF59 failed to induce detectable neutralizing antibodies (1:3.02). Furthermore, RVG-WT + AS03 induced significantly higher neutralizing antibody responses than the WT-PEG + AS03 control group (p < 0.0001), and a significant difference was also observed between the RVG-WT + MF59 and RVG-M6 + MF59 groups (p < 0.01). Conclusions: The glycoengineered Pichia pastoris expression system successfully produced uniform full-length rabies virus glycoprotein nanoparticles with high purity. When formulated with the AS03 adjuvant, RVG-WT induced high-titer neutralizing antibodies in mice, suggesting a promising strategy for the development of recombinant subunit vaccines against rabies. However, this study is limited by the absence of challenge studies and validation in target animal species, which will be further investigated in future work. Full article
(This article belongs to the Section Vaccine Advancement, Efficacy and Safety)
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32 pages, 619 KB  
Review
Salmonella Infections: Global Trends and Emerging Challenges
by Adishi Ranjan, Mahek Chandna, Nicole J. Stevens, Jana Kandil, Brianna Dinh, Macy Kuhn, Noor Mian, Bach Tran, Abdullah Hamid, Peter Kim and Taseen S. Desin
Microorganisms 2026, 14(4), 816; https://doi.org/10.3390/microorganisms14040816 - 2 Apr 2026
Viewed by 1301
Abstract
Salmonella remains a leading cause of foodborne illness worldwide, with non-typhoidal Salmonella (NTS) responsible for an estimated 93.8 million infections and substantial global morbidity and mortality. This review synthesizes current evidence on the epidemiology, molecular pathogenesis, and prevention of both typhoidal and nontyphoidal [...] Read more.
Salmonella remains a leading cause of foodborne illness worldwide, with non-typhoidal Salmonella (NTS) responsible for an estimated 93.8 million infections and substantial global morbidity and mortality. This review synthesizes current evidence on the epidemiology, molecular pathogenesis, and prevention of both typhoidal and nontyphoidal Salmonella, with emphasis on emerging challenges in disease control. We highlight key virulence mechanisms, including Salmonella pathogenicity islands and Type III secretion systems, that mediate host cell invasion, intracellular survival, and immune modulation, alongside differences in host adaptation, reservoirs, and clinical outcomes between major serotypes. Epidemiological synthesis demonstrates marked geographic variability in disease burden, driven by underreporting, limited diagnostic capacity, and social determinants of health, with particularly high mortality from invasive NTS (iNTS) disease in sub-Saharan Africa. This review further identifies major challenges, including the global rise of multidrug-resistant Salmonella lineages, the emergence of high-risk serotypes such as monophasic S. Typhimurium and S. Infantis, and the increasing complexity of transmission across the farm-to-fork continuum. While advances in whole genome sequencing and integrated surveillance platforms (e.g., PulseNet and GenomeTrakr) have improved outbreak detection and source attribution, gaps in cross-sector coordination persist. Collectively, the evidence underscores the need for integrated One Health approaches that link human, animal, and environmental systems, alongside strengthened surveillance, targeted prevention strategies, and antimicrobial stewardship. Advances in vaccination, including licensed typhoidal vaccines such as Ty21a and Vi polysaccharide, and conjugate vaccines, as well as emerging live attenuated and glycoconjugate candidates targeting NTS, represent promising strategies for reducing the global burden of Salmonella infections. Future efforts should focus on improving global surveillance harmonization, addressing environmental and climate-related drivers of transmission, and advancing vaccine development and implementation. Full article
(This article belongs to the Special Issue Salmonella Infections: Trends and Updates)
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20 pages, 4338 KB  
Article
A Tetravalent Recombinant Subunit Vaccine Provides Protection Against Mixed Challenges with Four Eimeria Species in Chickens
by Xiao Ma, Xichen Zhang, Jianhua Li, Pengtao Gong, Xiaocen Wang, Xin Li, Xu Zhang, Tao Zhang, Shuqin Cheng and Nan Zhang
Animals 2026, 16(7), 1087; https://doi.org/10.3390/ani16071087 - 1 Apr 2026
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Abstract
Chicken coccidiosis is a parasitic disease caused mainly by Eimeria tenella, Eimeria acervulina, Eimeria maxima, and Eimeria necatrix, with most cases presenting as mixed infections. Currently, although a subunit vaccine (CoxAbic) targeting Eimeria maxima via maternal immunization is commercially [...] Read more.
Chicken coccidiosis is a parasitic disease caused mainly by Eimeria tenella, Eimeria acervulina, Eimeria maxima, and Eimeria necatrix, with most cases presenting as mixed infections. Currently, although a subunit vaccine (CoxAbic) targeting Eimeria maxima via maternal immunization is commercially available, no genetically engineered multivalent subunit vaccine exists against mixed infections caused by these four Eimeria species simultaneously. Therefore, we developed a tetravalent recombinant subunit vaccine (designated TEIN) by fusing key antigen genes (TA4, 3-1E, IMP1, NA4) from these four Eimeria species and expressing the construct in Pichia pastoris. A total of 500 chickens were randomly allocated into 25 experimental subgroups (n = 20 each), consisting of five groups (control, challenged, adjuvant, pPIC9K, and TEIN) and five challenge conditions (infection with Eimeria tenella, Eimeria acervulina, Eimeria maxima, Eimeria necatrix, or a mixture of four species). Immunization was performed via leg intramuscular injection at 14 and 21 days of age. At 28 days of age, all chickens except the controls were orally challenged with 1 × 104 sporulated oocysts. Statistical analysis was performed using one-way or two-way ANOVA as appropriate. Results showed that chickens vaccinated with the TEIN subunit vaccine exhibited significantly elevated serum levels of IgY, IL-2, IL-10, and IFN-γ, as well as an increased splenic lymphocyte CD4+/CD8+ ratio. The anticoccidial indices (ACI) against Eimeria tenella, Eimeria acervulina, Eimeria maxima, and Eimeria necatrix, and their mixed infection reached 174.82, 174.58, 174.41, 180.61, and 175.95, respectively. Moreover, no significant differences were observed in hematological parameters, serum biochemical markers, or histopathological findings between the vaccinated and control groups. These results demonstrate the vaccine’s potential as a promising candidate for controlling mixed coccidial infections. Full article
(This article belongs to the Special Issue Coccidian Parasites: Epidemiology, Control and Prevention Strategies)
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23 pages, 2616 KB  
Article
In Silico Design and Characterization of the Essential Outer-Membrane Lipoprotein LolB-Derived Multi-Epitope Vaccine Candidate Against Pseudomonas aeruginosa
by Sinethemba H. Yakobi and Uchechukwu U. Nwodo
Methods Protoc. 2026, 9(2), 52; https://doi.org/10.3390/mps9020052 - 1 Apr 2026
Viewed by 359
Abstract
Pseudomonas aeruginosa causes severe healthcare-associated infections, yet no vaccine has been licenced. To circumvent the antigenic variability of classical surface antigens, we evaluated LolB—an essential outer-membrane lipoprotein whose periplasmic orientation favours T-cell-dominant mechanisms with potential antibody access via outer-membrane vesicles (OMVs) or bacteriolysis. [...] Read more.
Pseudomonas aeruginosa causes severe healthcare-associated infections, yet no vaccine has been licenced. To circumvent the antigenic variability of classical surface antigens, we evaluated LolB—an essential outer-membrane lipoprotein whose periplasmic orientation favours T-cell-dominant mechanisms with potential antibody access via outer-membrane vesicles (OMVs) or bacteriolysis. An integrative in silico pipeline combined multi-strain conservation (20 isolates), epitope discovery (B- and T-cell), safety filters, physicochemical profiling, de novo/refined 3D modelling, molecular dynamics (MD), and docking to TLR4/MD-2. LolB was highly conserved (95–100% identity) under strong purifying selection (dN/dS = 0.15). A conformational B-cell hotspot centred on Q72 mapped to a solvent-accessible flexible loop. Two class II epitopes—LAAQNSPLT and FLGSAAAVS—showed predicted high affinity (IC50 < 10 nM), non-toxicity, and broad coverage, with the pooled set achieving 98.6% global HLA coverage in silico. The final 119-aa construct (N-terminal hBD-3 adjuvant; GPGPG linkers) was compact and tractable (MW = 12.7 kDa; instability index < 40; near-neutral GRAVY) and scored higher for antigenicity than native LolB (VaxiJen 0.82 vs. 0.41). MD supported thermal stability up to 350 K, linker RMSF < 1.5 Å, and a stable 18.2 ± 2.8 Å interdomain spacing. Docking predicted a 1420 Å2 interface and ΔG = −10.2 kcal·mol−1 (Kd = 28 nM) with reproducible polar contacts, suggesting productive TLR4/MD-2 engagement. A conservative R42A/K variant is proposed to temper IFN-γ bias. This work therefore suggests an essentiality-anchored LolB-derived multi-epitope construct as a computational vaccine candidate against multidrug-resistant P. aaeruginosa and defines specific experimentally testable hypotheses for future in vitro/in vivo assessment. Essentiality-anchored epitope selection plus adjuvant-surface engineering yielded a structurally coherent, immunologically rational LolB-derived multi-epitope vaccine warranting experimental validation. Full article
(This article belongs to the Section Molecular and Cellular Biology)
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