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13 pages, 838 KB  
Article
Multi-Component Vaccine Candidates Against Non-Typeable Haemophilus influenzae
by Nouria Belkacem, Ala-Eddine Deghmane and Muhamed-Kheir Taha
Vaccines 2025, 13(9), 892; https://doi.org/10.3390/vaccines13090892 - 22 Aug 2025
Viewed by 110
Abstract
Background: Haemophilus influenzae (Hi), a Gram-negative bacterium, is divided into two broad categories: encapsulated and non-capsulated isolates, also called non-typeable Hi isolates (NTHi). NTHi has become prevalent since the introduction of the vaccine against Hi of serotype b. Hi can cause local [...] Read more.
Background: Haemophilus influenzae (Hi), a Gram-negative bacterium, is divided into two broad categories: encapsulated and non-capsulated isolates, also called non-typeable Hi isolates (NTHi). NTHi has become prevalent since the introduction of the vaccine against Hi of serotype b. Hi can cause local infections on respiratory mucosal surfaces and urogenital infections, which can lead to septic abortion in pregnant women. It can also cause invasive infections such as meningitis and septicemia. Moreover, NTHi isolates are becoming increasingly resistant to antibiotics. Vaccines targeting NTHi are not yet available. As these NTHi isolates are not encapsulated, vaccines should target proteins at the bacterial surface. However, vaccine development is hindered by the high variability of these proteins. We aimed to identify conserved outer membrane proteins (OMPs) for vaccines against NTHi. Methods: We analyzed core-genome multilocus sequence typing (cgMLST) of 1144 genomes of Hi collected between 2017 and 2022 and, of these, identified 514 conserved genes that encoded OMPs. We focused on two specific OMPs: Haem1295, encoding the protein P5 (P5), and Haem1040, encoding the protein 26 (P26). P5 is known to bind human complement regulatory protein factor H (FH), while both P5 and P26 are involved in enhancing immune responses. The genes encoding these proteins were cloned, overexpressed, purified, and tested in both active and passive protection models using systemic infection in mice. Results: P5 and P26 were found to be immunogenic during human infections. Vaccination with these proteins conferred protection against both homologous and heterologous NTHi isolates in mice, suggesting broad cross-protection. Conclusions: P5 and P26 are promising vaccine candidates showing cross-protection against NTHi and offering the additional benefit of targeting bacterial virulence factors, enhancing vaccine efficacy against NTHi isolates. Full article
(This article belongs to the Section Vaccine Design, Development, and Delivery)
19 pages, 2215 KB  
Article
Antimicrobial Resistance of Salmonella and Characterization of Two Mcr-1-Harboring Isolates from Pork Products in Guangdong, China
by Zifeng Mai, Lusan Wei, Chunlei Shi and Zeqiang Zhan
Foods 2025, 14(17), 2933; https://doi.org/10.3390/foods14172933 - 22 Aug 2025
Viewed by 81
Abstract
Salmonella is a major foodborne pathogen that poses an increasing threat due to the emergence of mcr-1-mediated colistin resistance. However, data on mcr-1-positive Salmonella in pork products are limited. In this study, 457 samples collected in 2023 from pig slaughterhouses in [...] Read more.
Salmonella is a major foodborne pathogen that poses an increasing threat due to the emergence of mcr-1-mediated colistin resistance. However, data on mcr-1-positive Salmonella in pork products are limited. In this study, 457 samples collected in 2023 from pig slaughterhouses in Guangdong province were investigated to determine the prevalence and genomic characteristics of mcr-1-positive Salmonella isolates. We found that 92 Salmonella isolates (20.1%, 92/457) were recovered, representing six serotypes, including Salmonella Typhimurium (n = 29) and Salmonella Rissen (n = 29). High resistance to tetracycline (90.2%, 83/92) and multidrug resistance (58.7%, 54/92) were observed. Critically, two colistin-resistant Salmonella Kentucky ST198 isolates (2.2%) harboring mcr-1 on transferable IncI2 plasmids were identified. Genomic analysis revealed a novel multidrug resistance region (MRR, ~57 kb) inserted into the bcfH locus (containing floR, qnrS1, blaCTX-M-55, and aph (3’)-Ia) and a variant Salmonella Genomic Island 1 (SGI1-KI, containing tet (A), sul1, qacEΔ1 and aadA7) in these isolates. The MRR and SGI1-KI may enhance bacterial survival under antibiotic selection pressure. Phylogenetic analysis showed close relatedness to human clinical strains, suggesting food chain transmission. The findings highlight a high antimicrobial resistance burden, the emergence of transferable last-resort colistin resistance (mcr-1), and acquisition of complex resistance determinants (MRR, SGI1-KI), underscoring an urgent need for enhanced “One Health” surveillance. Full article
(This article belongs to the Section Food Microbiology)
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19 pages, 908 KB  
Review
Quantitative Methods for Evaluating Antibody Responses to Pneumococcal Vaccines: A Scoping Review
by Yumiko Hayashi, Fleurette Mbuyakala Domai and Bhim Gopal Dhoubhadel
Trop. Med. Infect. Dis. 2025, 10(8), 236; https://doi.org/10.3390/tropicalmed10080236 - 21 Aug 2025
Viewed by 211
Abstract
Streptococcus pneumoniae remains a leading cause of invasive diseases, particularly affecting young children and the elderly. Currently, two main types of pneumococcal vaccines are commercially available: polysaccharide vaccine (PPSV23) and conjugate vaccines (e.g., PCV20). Of over 100 identified pneumococcal serotypes, vaccines targeting 24 [...] Read more.
Streptococcus pneumoniae remains a leading cause of invasive diseases, particularly affecting young children and the elderly. Currently, two main types of pneumococcal vaccines are commercially available: polysaccharide vaccine (PPSV23) and conjugate vaccines (e.g., PCV20). Of over 100 identified pneumococcal serotypes, vaccines targeting 24 serotypes covered by PPSV23 and PCV20 (19 serotypes overlap between the two vaccines) have been developed, with serotype distribution varying by geography, age, and time. The immune response to pneumococcal vaccines differs across serotypes, vaccine types (polysaccharide vs. conjugate), and host factors. Quantitative methods for antibody assessment—particularly newer high-throughput assays—have emerged since 2000 to address limitations in conventional approaches. However, these methods have not been comprehensively reviewed. This scoping review aimed to systematically map the existing literature on quantitative methods used to assess antibody responses to pneumococcal vaccines. Specific objectives included the following: 1. summarizing conventional and novel quantitative immunoassays; 2. evaluating the current state of validation and application of these methods; 3. identifying knowledge gaps and methodological challenges. We followed the PRISMA-ScR guidelines. We included the following: 1. peer-reviewed, open-access papers related to immunoassays used for pneumococcal antibody assessment; 2. articles written in English; 3. Studies published between 2000 and 2023. We excluded the following: 4. studies focusing on other pathogens, employing different analytical methods, or using animal models. Articles meeting the eligibility criteria were primarily retrieved from PubMed and Scopus. If free full-text versions were unavailable there, Google Scholar or the original journal databases were consulted. All references were exported to EndNote 20 for further management. At the beginning of the review, a data-charting form was developed based on prior studies and commonly addressed themes. Additional charts were created to accommodate newly identified variables during the review. All charting tools were reviewed and finalized through discussion among all research team members. The included studies were classified into five thematic groups: 1. general descriptions of quantitative assessment methods, 2. assay development and validation, 3. comparative studies, 4. technical details of assay development, 5. interpretation of assay application findings. Of 1469 articles from PubMed and 2946 articles from Scopus initially identified, 55 articles met the inclusion criteria. The earliest methods included radioimmunoassays, later replaced by WHO-standardized ELISA. While ELISA remains the gold standard, it is limited by labor, cost, and throughput. Multiplex immunoassays (MIAs), including Luminex-based platforms, have demonstrated advantages in efficiency and scalability. However, many MIAs did not initially meet WHO validation criteria. More recent assays show an improved performance, yet interlaboratory variability and lack of standardized protective thresholds remain major limitations. This review provides the first comprehensive mapping of quantitative antibody assessment methods for pneumococcal vaccines. Although ELISA continues to serve as the benchmark, MIAs represent a promising next-generation approach. Continued efforts are needed to harmonize assay validation protocols and establish global standards for protective thresholds, which will enhance the reliability of vaccine efficacy monitoring across diverse populations. Full article
(This article belongs to the Section Infectious Diseases)
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10 pages, 578 KB  
Article
IgG Antibodies to Pneumococcal Serotypes 1 and 5 in Relation to PCV13 Vaccination Status in Children Aged Under 5 Years in Lao PDR: A Cross-Sectional Survey
by Zheng Quan Toh, Ke Xin Tang, Keoudomphone Vilivong, Jana Lai, Toukta Bounkhoun, Valin Chanthaluanglath, Anisone Chanthongthip, Anne Balloch, Paul N. Newton, Audrey Dubot-Pérès, David A. B. Dance, Paul V. Licciardi and Fiona M. Russell
Vaccines 2025, 13(8), 873; https://doi.org/10.3390/vaccines13080873 - 18 Aug 2025
Viewed by 329
Abstract
Background/Objectives: Pneumococcal serotypes 1 and 5 are associated with invasive pneumococcal disease (IPD). However, data on the circulation of these serotypes in Asia following the introduction of the pneumococcal conjugate vaccine (PCV) is limited. The Lao People’s Democratic Republic (Lao PDR) introduced PCV13 [...] Read more.
Background/Objectives: Pneumococcal serotypes 1 and 5 are associated with invasive pneumococcal disease (IPD). However, data on the circulation of these serotypes in Asia following the introduction of the pneumococcal conjugate vaccine (PCV) is limited. The Lao People’s Democratic Republic (Lao PDR) introduced PCV13 into its national immunisation programme in 2013. We undertook a serosurvey to assess the IgG responses to serotypes 1 and 5 from a convenience sample of children aged under 5 years in Vientiane, Lao PDR. Methods: This cross-sectional analysis used a convenience sample of the close contacts of children under five years old who had been hospitalised with acute respiratory infections between 2013 and 2016 in Vientiane, Lao PDR. Serotype-specific IgG concentrations to serotypes 1 and 5 were measured using a modified WHO ELISA method. Results: A total of 214 participants were included, 130 of whom were unvaccinated and 84 were vaccinated with PCV13. Compared to unvaccinated participants, a higher number of PCV-vaccinated participants met the IgG threshold for IPD (≥0.35 μg/mL) [41.5% (54/130) vs. 71.4% (60/84)] for serotype 1. In contrast, for serotype 5, a similar number of participants in the PCV-vaccinated and unvaccinated group met the IgG threshold for IPD (85.7% (72/84) vs. 82.3% (107/130). Among unvaccinated children, serotype 1 IgG levels peaked at 12 and 23 months at 0.49 µg/mL (95% CIs: 0.25–0.96), while serotype 5 IgG levels were similar across age groups, ranging from 0.55 to 0.79 µg/mL. Conclusions: Our findings indicate the considerable circulation of serotypes 1 and 5 within the community in Lao PDR. Ongoing surveillance is important for informing PCV vaccination strategies. Full article
(This article belongs to the Special Issue Host Immunity and Vaccines for Respiratory Pathogens)
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16 pages, 4167 KB  
Article
A Novel Lytic Salmonella Phage Harboring an Unprecedented Tail-Protein Domain Combination Capable of Lysing Cross-Host-Transmitted Salmonella Strains
by Ling Zhang, Mingqiang Guo, Xiaoyu Ma, Wei Wang, Wanpeng Ma, Yifan Liu, Junxiang Wei and Zhanqiang Su
Foods 2025, 14(16), 2850; https://doi.org/10.3390/foods14162850 - 17 Aug 2025
Viewed by 342
Abstract
The emergence of multidrug-resistant Salmonella poses a significant threat to global public health and food safety, necessitating the urgent search for new strategies to replace conventional antibiotics. Phages are viruses that can directly target bacteria and have garnered attention in recent years for [...] Read more.
The emergence of multidrug-resistant Salmonella poses a significant threat to global public health and food safety, necessitating the urgent search for new strategies to replace conventional antibiotics. Phages are viruses that can directly target bacteria and have garnered attention in recent years for their development as antibiotic alternatives. In this study, 4458 samples were collected from farms, supermarkets, and human feces, yielding 65 strains of Salmonella, which were serotyped using multiplex PCR. Subsequently, a lytic phage was isolated and identified using the dominant serotype of Salmonella as the host bacterium. We further explored the biological characteristics of this phage through host range, growth properties, and genomic analysis. Finally, we analyzed the potential of the phage to block the cross-host transmission of Salmonella, combining PFGE Salmonella classification, strain sources, and phage lytic phenotypes. The results showed that phage gmqsjt-1 could lyse 69.23% (45/65) of Salmonella, of which 75.56% (34/45) were resistant strains. The optimal multiplicity of infection (MOI) for gmqsjt-1 was 0.01, with a latent period of about 10 min, maintaining high activity within the temperature range of 30 to 60 °C and pH range of 2 to 13. No virulence or resistance genes were detected in the gmqsjt-1 genome, which carries two tail spike proteins (contain FAD binding_2 superfamily, the Tail spike TSP1/Gp66 N-terminal domain, and the Pectin lyase fold) and a holin–lysozyme–spanin lytic system. Phylogenetic classification indicates that phage gmqsjt-1 belongs to a new genus and species of an unnamed family within the class Caudoviricetes. PFGE classification results show a high genetic relationship among human, farm animal, and food source Salmonella, and the comprehensive lytic phenotype reveals that phage gmqsjt-1 can lyse Salmonella with high genetic correlation. These results suggest that this novel lytic Salmonella phage has the potential to inhibit cross-host transmission of Salmonella, making it a promising candidate for developing alternative agents to control Salmonella contamination sources (farms), thereby reducing the risk of human infection with Salmonella through ensuring food system safety. Full article
(This article belongs to the Section Food Microbiology)
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20 pages, 2452 KB  
Article
The Importance of Solution Studies for the Structural Characterization of the Enterovirus 5’ Cloverleaf
by Morgan G. Daniels, Meagan E. Werner, Xiaobing Zuo and Steven M. Pascal
Viruses 2025, 17(8), 1127; https://doi.org/10.3390/v17081127 - 16 Aug 2025
Viewed by 373
Abstract
Enteroviruses initiate genomic replication via a highly conserved mechanism that is controlled by an RNA platform, also known as the 5’ cloverleaf (5’CL). Here, we present a biophysical analysis of the 5’CL conformation of three enterovirus serotypes under various ionic conditions, utilizing CD [...] Read more.
Enteroviruses initiate genomic replication via a highly conserved mechanism that is controlled by an RNA platform, also known as the 5’ cloverleaf (5’CL). Here, we present a biophysical analysis of the 5’CL conformation of three enterovirus serotypes under various ionic conditions, utilizing CD spectroscopy, size-exclusion chromatography, and small-angle X-ray scattering. In general, a tendency toward a smaller monomeric hydrodynamic radius in the presence of salts was observed, but the exact structural signature of each 5’CL varied depending upon the serotype. Rhinovirus B14 (RVB14) exhibited at least two monomeric conformations and a low propensity for dimerization, while poliovirus 1 (PV1) showed a high propensity for dimerization, which was enhanced by the presence of salts. Enterovirus D70 was observed to be somewhat intermediate, with primarily a monomeric structure, but possessing some potential for dimerization. The equilibrium between the two monomeric and the dimeric conformations is also discussed. These results indicate that the 5’CL conformation may be more complex than the current literature suggests, thus underscoring the need for a combined crystal and solution approach for the accurate representation of the 5’CL conformation, and the conformation of other RNA structural elements, under native conditions. Full article
(This article belongs to the Special Issue An Update on Enterovirus Research, 2nd Edition)
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14 pages, 926 KB  
Article
Safety and Immunogenicity of a 23-Valent Pneumococcal Polysaccharide Vaccine (PPSV23) in Chinese Children, Adults and the Elderly: A Phase 4, Randomized, Double-Blind, Active-Controlled Clinical Trial
by Xiaoyu Liu, Gang Shi, Yuanyuan Dong, Wanqi Yang, Yinan Wang, Xianying Ye, Juxiang Zhang, Xinyi Yang, Dan Yu, Dan Song, Yuehong Ma, Zeng Wang, Hong Li and Weijun Hu
Vaccines 2025, 13(8), 866; https://doi.org/10.3390/vaccines13080866 - 15 Aug 2025
Viewed by 418
Abstract
Objectives: This randomized, double-blind, active-controlled non-inferiority phase 4 clinical trial was conducted to evaluate the immunogenicity and safety of a 23-valent pneumococcal polysaccharide vaccine (PPSV23) compared to an active comparator vaccine. Methods: Pneumococcal vaccine-naïve participants aged ≥2 years were randomly assigned in a [...] Read more.
Objectives: This randomized, double-blind, active-controlled non-inferiority phase 4 clinical trial was conducted to evaluate the immunogenicity and safety of a 23-valent pneumococcal polysaccharide vaccine (PPSV23) compared to an active comparator vaccine. Methods: Pneumococcal vaccine-naïve participants aged ≥2 years were randomly assigned in a 2:1 ratio to receive a single dose of either the investigational vaccine (n = 1199) or the comparator vaccine (n = 600). Immunogenicity was evaluated at baseline and 30 days post-vaccination by measuring serotype-specific IgG antibodies against all 23 pneumococcal serotypes using enzyme-linked immunosorbent assay. The primary outcome was seroconversion, defined as a ≥two-fold increase in serotype-specific IgG antibody titers at day 30 compared to baseline. Results: At one month post-vaccination, seroconversion rates for each of the 23 serotypes ranged from 59.22% to 95.67% in the treatment group, compared to 59.66% to 94.07% in the control group. Non-inferiority was demonstrated for all serotypes, with the lower bounds of the 95% confidence intervals (95%CI) for rate differences exceeding the predefined −10% margin. Moreover, superiority was observed for 12 serotypes (6B, 23F, 1, 2, 4, 8, 9N, 9V, 11A, 15B, 17F and 18C), as the lower bounds of their 95%CI for rate differences were above 0. Adverse reactions were reported in 236 (19.68%) participants of the investigational group and 118 (19.67%) of the control group within 30 days post-vaccination, with no significant differences between groups. Conclusions: The PPSV23 vaccine administered among individual aged ≥2 years was safe, well tolerated and immunogenic, eliciting an immune response either comparable to or higher than control vaccine. These findings support its use as a safe and effective option for pneumococcal immunization. Full article
(This article belongs to the Special Issue Safety and Immunogenicity of Vaccination)
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20 pages, 2524 KB  
Article
Wild Fauna in Oman: Foot-and-Mouth Disease Outbreak in Arabyan Oryx (Oryx leucorix)
by Massimo Giangaspero, Salah Al Mahdhouri, Sultan Al Bulushi and Metaab K. Al-Ghafri
Animals 2025, 15(16), 2389; https://doi.org/10.3390/ani15162389 - 14 Aug 2025
Viewed by 322
Abstract
The Sultanate of Oman boasts remarkable biodiversity, exemplified by such species as the Arabian leopard (Panthera pardus nimr) and the Arabian oryx (Oryx leucoryx), national symbols that highlight the extensive conservation efforts required to protect the country’s natural heritage. [...] Read more.
The Sultanate of Oman boasts remarkable biodiversity, exemplified by such species as the Arabian leopard (Panthera pardus nimr) and the Arabian oryx (Oryx leucoryx), national symbols that highlight the extensive conservation efforts required to protect the country’s natural heritage. During decades, Omani authorities have taken significant measures to safeguard wildlife and preserve the natural environment. A sanctuary dedicated to the reintroduction of the Arabian Oryx, after extinction in nature in 1972, was established in 1980 in the Al Wusta Governorate under the patronage of the Royal Diwan and currently administrated by the recently established Environment Authority. During the almost 40 years since the reintroduction and the creation of the sanctuary, the oryx population has grown slowly but constantly. In 2021, the sanctuary hosted 738 oryx, allowing the start of the reintroduction of the species into the natural environment. Small groups of animals were released into the wild in selected areas. No animal health adverse events were recorded, and mortality was generally due to injuries received as a consequence of fighting, in particular during mating season. Standard veterinary care, including control of internal and external parasites, was regularly provided. In some occasions, immunization against certain diseases, such as clostridial infections, pasteurellosis, or mycoplasmosis, was also applied. In 2023, an FMD outbreak in cattle reported in Dhofar, about 500 km from the Al Wusta sanctuary, motivated specific prophylactic actions to prevent the risk of diffusion to oryx. From December 2023 to January 2024, an immunization program was undertaken using an FMD vaccine against serotypes A, O, and SAT 1, mostly in male oryx, while pregnant oryx were avoided for abortion risk due to handling. The following year, in January 2025, a severe outbreak occurred in oryx herds held in the sanctuary. The rapid onset and the spread of clinical symptoms among animals (100% morbidity in the second day after the first appearance of signs in some individuals) were suggestive of a highly contagious disease. The animals suffered from severe depression and inappetence, rapidly followed by abundant salivation, erosions of the oral mucosa and tongue, and diarrhea, with a short course characterized by prostration and death of the animal in the most severe cases. Therapeutical attempts (administration of antibiotics and rehydration) were mostly ineffective. Laboratory investigations (ELISA and PCR) ruled out contagious bovine pleuropneumonia (CBPP), Johne’s disease and Peste des petits ruminants (PPR). Both serology and antigen detection showed positiveness to foot-and-mouth disease (FMD). Out of a total population of 669 present in the sanctuary at the beginning of the outbreak, 226 (33.78%) oryx died. Despite the vaccinal status, the 38.49% of dead animals resulted being vaccinated against FMD. Taking into account the incalculable value of the species, the outbreak represented a very dangerous event that risked wiping out the decades of conservation efforts. Therefore, all the available means, such as accrued biosecurity and adequate prophylaxis, should be implemented to prevent the recurrence of such health risks. The delicate equilibrium of wild fauna in Oman requires study and support for an effective protection, in line with the national plan “Vision 2040”, targeting the inclusion of the Sultanate within the 20 best virtuous countries for wildlife protection. Full article
(This article belongs to the Special Issue Wildlife Diseases: Pathology and Diagnostic Investigation)
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13 pages, 1290 KB  
Systematic Review
Immunogenicity as a Predictor of Influenza Vaccine Efficacy: A Systematic Review
by André Miguel Martins, Luis Félix Valero Juan, Marlene Santos and João P. Martins
Vaccines 2025, 13(8), 859; https://doi.org/10.3390/vaccines13080859 - 14 Aug 2025
Viewed by 424
Abstract
Background/Objectives: Influenza represents a significant burden on global public health, and vaccination is the most effective strategy to reduce it. The large investment in vaccination programs and the need for adjustments in vaccine serotypes are important reasons for evaluating the influenza vaccine’s efficacy [...] Read more.
Background/Objectives: Influenza represents a significant burden on global public health, and vaccination is the most effective strategy to reduce it. The large investment in vaccination programs and the need for adjustments in vaccine serotypes are important reasons for evaluating the influenza vaccine’s efficacy every year. Establishing a relationship between immunogenicity data and efficacy is also crucial for predicting the efficacy of a vaccine during its development. Antibody response measurement is one of the most common methods for evaluating immunogenicity, particularly in vaccines and biologics. The aim of this systematic review was to define a model that relates the immunogenicity of a given vaccine to its efficacy, based on hemagglutination inhibition titer levels. Methods: To achieve this goal, information was gathered from articles linking immunogenicity with the efficacy of the influenza vaccine in the Medline and Scopus databases. Different mathematical models were developed and applied to assess the relationship between HAI titers and the effectiveness of the flu vaccine. This analysis was conducted for the various existing vaccines, for the different influenza virus strains, and for their efficacy in paediatric populations. Results: The r2 obtained ranged from 0.2579 to 0.966, which points to the importance of this immunological factor in the efficacy of the influenza vaccine. Conclusions: The efficacy values for titer level 40 confirm the validity of the data provided by Hobson. Full article
(This article belongs to the Special Issue Influenza Virus Vaccines and Vaccination)
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29 pages, 4115 KB  
Article
In Silico Design of a Multiepitope Vaccine Against Intestinal Pathogenic Escherichia coli Based on the 2011 German O104:H4 Outbreak Strain Using Reverse Vaccinology and an Immunoinformatic Approach
by Eman G. Youssef, Khaled Elnesr and Amro Hanora
Diseases 2025, 13(8), 259; https://doi.org/10.3390/diseases13080259 - 13 Aug 2025
Viewed by 255
Abstract
Background: While most Escherichia coli strains are harmless members of the gastrointestinal microbiota, certain pathogenic variants can cause severe intestinal and extraintestinal diseases. A notable outbreak of E. coli O104:H4, involving both enteroaggregative (EAEC) and enterohemorrhagic (EHEC) strains, occurred [...] Read more.
Background: While most Escherichia coli strains are harmless members of the gastrointestinal microbiota, certain pathogenic variants can cause severe intestinal and extraintestinal diseases. A notable outbreak of E. coli O104:H4, involving both enteroaggregative (EAEC) and enterohemorrhagic (EHEC) strains, occurred in Europe, resulting in symptoms ranging from bloody diarrhea to life-threatening colitis and hemolytic uremic syndrome (HUS). Since treatment options remain limited and have changed little over the past 40 years, there is an urgent need for an effective vaccine. Such a vaccine would offer major public health and economic benefits by preventing severe infections and reducing outbreak-related costs. A multiepitope vaccine approach, enabled by advances in immunoinformatics, offers a promising strategy for targeting HUS-causing E. coli (O104:H4 and O157:H7 serotypes) with minimal disruption to normal microbiota. This study aimed to design an immunogenic multiepitope vaccine (MEV) construct using bioinformatics and immunoinformatic tools. Methods and Results: Comparative proteomic analysis identified 672 proteins unique to E. coli O104:H4, excluding proteins shared with the nonpathogenic E. coli K-12-MG1655 strain and those shorter than 100 amino acids. Subcellular localization (P-SORTb) identified 17 extracellular or outer membrane proteins. Four proteins were selected as vaccine candidates based on transmembrane domains (TMHMM), antigenicity (VaxiJen), and conservation among EHEC strains. Epitope prediction revealed ten B-cell, four cytotoxic T-cell, and three helper T-cell epitopes. Four MEVs with different adjuvants were designed and assessed for solubility, stability, and antigenicity. Structural refinement (GALAXY) and docking studies confirmed strong interaction with Toll-Like Receptor 4 (TLR4). In silico immune simulations (C-ImmSim) indicated robust humoral and cellular immune responses. In Conclusions, the proposed MEV construct demonstrated promising immunogenicity and warrants further validation in experimental models. Full article
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10 pages, 351 KB  
Article
Serotype Distribution of Aggregatibacter actinomycetemcomitans in Periodontitis Patients
by Nabil Khzam, Omar Kujan, Dorte Haubek and Leticia Algarves Miranda
Pathogens 2025, 14(8), 805; https://doi.org/10.3390/pathogens14080805 - 13 Aug 2025
Viewed by 333
Abstract
Aim: The aim of the current investigation was to detect serotypes of Aggregatibacter actinomycetemcomitans in a cohort of Western Australians diagnosed with periodontitis. Materials and Methods: A total of 64 subjects were selected. Intra-oral samples were taken from every subject in the present [...] Read more.
Aim: The aim of the current investigation was to detect serotypes of Aggregatibacter actinomycetemcomitans in a cohort of Western Australians diagnosed with periodontitis. Materials and Methods: A total of 64 subjects were selected. Intra-oral samples were taken from every subject in the present investigation. Periodontal, radiographical, and microbiological analyses were conducted. A polymerase chain reaction was employed to investigate the presence of Aggregatibacter actinomycetemcomitans serotypes. Results: Only twelve (18.75%) patients were tested positive for Aggregatibacter actinomycetemcomitans. The most dominant serotypes of Aggregatibacter actinomycetemcomitans in this group were serotype e (80.55%), followed by serotype c (52.77%). Both serotypes b and d were absent in the present investigation. Serotype e presented in isolation or combined with other serotypes. The other serotypes tend to be present alone, but when they were isolated together, they were always combined with serotype e. It seems that serotype e of Aggregatibacter actinomycetemcomitans is associated with those who live in rural areas (p = 0.003), and those with low education (p = 0.041), and severe forms of periodontitis in this cohort. Conclusions: In patients diagnosed with severe periodontitis, serotype e was dominant in this population. Serotypes b and d did not appear in the present study. Full article
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17 pages, 3414 KB  
Article
Acute Febrile Illness Associated with an Emerging Dengue 4 GIIb Variant Causing Epidemic in León, Nicaragua 2022
by Omar Zepeda, Edwing C. Cuadra, Daniel O. Espinoza, Yerun Zhu, Hernán Vanegas, Alexis Domeracki, Rodrigo A. Mora-Rodríguez, Anne Piantadosi, Jesse J. Waggoner, Armando J. Matute, Lakshmanane Premkumar, Aravinda M. de Silva, Matthew H. Collins, Megan E. Reller and Filemón Bucardo
Viruses 2025, 17(8), 1113; https://doi.org/10.3390/v17081113 - 13 Aug 2025
Viewed by 641
Abstract
Historically, DENV-4 has been rarely associated with epidemics and has been less well-studied than DENV-1 to -3. Epidemic dengue struck several South and Central American countries in 2022, with Nicaragua reporting the highest incidence. In an acute febrile illness (AFI) cohort enrolled from [...] Read more.
Historically, DENV-4 has been rarely associated with epidemics and has been less well-studied than DENV-1 to -3. Epidemic dengue struck several South and Central American countries in 2022, with Nicaragua reporting the highest incidence. In an acute febrile illness (AFI) cohort enrolled from June to September 2022, 58 (34%) of 172 patients had PCR-confirmed dengue, of which 46 (79%) were serotyped as DENV-4. In this cohort, acute dengue, as a proportion of AFI, increased from 8% in June to a peak of 58% in August. Genome sequencing and phylogenetic analysis identified a lineage of DENV-4 Genotype IIb (GIIb) with six amino acid substitutions on the surface-exposed regions of the envelope (E) protein as compared to a reference sequence from 2005. Indeed, two of these mutations appear to be novel and located at G172E or near N174K, an antigenic epitope on domain I. Most (90%, 43/48) DENV-4 patients had pre-existing DENV IgG (secondary dengue), at the acute phase. Secondary dengue was associated with the male sex (prevalence ratio (PR)), 6.88) and being younger than 11 years of age (PR, 8.38). Further analysis showed no association between past Zika exposure and DENV-4 acute illness in older subjects (≥12 years of age). In conclusion, our study describes an epidemic of DENV-4 in León, Nicaragua, associated with a novel lineage of genotype GIIb, which contains two amino acid changes not observed in DENV-4 before 2022. Full article
(This article belongs to the Section Human Virology and Viral Diseases)
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16 pages, 2261 KB  
Case Report
Cerebral Malformations in Calves Presumed to Be Associated with an Outbreak of Bluetongue Virus Serotype 3 Infection
by Peter Lennart Venjakob, Sarah Schmidt, Patrick Hoch, Daniela Farke, Maximilien Lépine, Kernt Köhler and Walter Grünberg
Animals 2025, 15(16), 2359; https://doi.org/10.3390/ani15162359 - 11 Aug 2025
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Abstract
Bluetongue is a vector-borne viral infectious disease primarily affecting ruminants, transmitted by biting midges of the Culicoides species. The first bluetongue virus 3 (BTV-3) cases occurred in Hesse, Germany, in July 2024. From December 2024 onwards, field veterinarians observed calves born with neurological [...] Read more.
Bluetongue is a vector-borne viral infectious disease primarily affecting ruminants, transmitted by biting midges of the Culicoides species. The first bluetongue virus 3 (BTV-3) cases occurred in Hesse, Germany, in July 2024. From December 2024 onwards, field veterinarians observed calves born with neurological symptoms. A convenience sample of affected calves were admitted to the Veterinary Teaching Hospital at Justus-Liebig-University Giessen, Germany. A total of 13 calves from unvaccinated dams with pronounced neurological symptoms and positive PCR results for BTV-3 were studied. General and neurological examinations were performed and a blood sample was obtained for hematologic, blood biochemical and blood gas analysis. In 11 calves, magnetic resonance imaging (MRI) was performed. Due to the severe neurological lesions, all calves were euthanized and postmortem examinations were performed. The neurological examination of the calves revealed neurological indications consistent with diffuse forebrain disease. MRI revealed that all calves exhibited various stages of cortical parenchyma cell loss and secondary enlargement of the lateral ventricles. Postmortem examination revealed moderate to severe hydrocephalus internus or hydranencephaly. The results of clinical and neurological examinations, MRI, and postmortem examination, indicate severe impairment of brain development presumably associated with transplacental BTV-3 infection. Epidemiologic data and health records from the originating farms suggest that neurologic malformations developed after BTV-3 infection between 95 and 227 of the gestation period. Full article
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16 pages, 2967 KB  
Article
Adeno-Associated Viral Gene Delivery of Wild-Type Human Tau Induces Progressive Hyperphosphorylation and Neuronal Cell Death in the Hippocampi of Middle-Aged Rats
by Ryan C. Gorzek, Aurelie Joly-Amado, Natalia Hurst-Calle, Graham L. Gabrielson, Maxine Miller, Sue Osting, Kevin R. Nash and Corinna Burger
Cells 2025, 14(16), 1238; https://doi.org/10.3390/cells14161238 - 11 Aug 2025
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Abstract
Tau aggregation and the subsequent formation of neurofibrillary tangles are hallmarks of Alzheimer’s disease (AD) and other dementias. While accumulation of tau aggregates is believed to contribute to cell death and neurodegeneration, tau aggregation and hyperphosphorylation are also correlated with cognitive impairment in [...] Read more.
Tau aggregation and the subsequent formation of neurofibrillary tangles are hallmarks of Alzheimer’s disease (AD) and other dementias. While accumulation of tau aggregates is believed to contribute to cell death and neurodegeneration, tau aggregation and hyperphosphorylation are also correlated with cognitive impairment in AD. To understand the role of tau in neurodegeneration, we used adeno-associated virus serotype 9 (AAV9) to express human wild-type 4-repeat, 0-N-terminus tau isoform (AAV-htau) in the Cornu ammonis area 1 (CA1) region of the dorsal hippocampus of adult 6-month-old Fischer 344 rats. AAV expressing green fluorescent protein (AAV-GFP) or uninjected rats were used as controls. To characterize early phenotypes, we investigated pathological changes at 3, 8, and 12 weeks post-injection of AAV-htau. Our results show that at 3 weeks post-injection, there was already robust expression of human tau in the CA1 region of animals injected with AAV-htau compared to those injected with AAV-GFP or the uninjected controls. At 12 weeks post-injection, area CA1 showed a statistically significant reduction in cell number and a thinner neuronal layer all throughout the anterior dorsal hippocampus, as well as redistribution to the somatodendritic areas of CA1. We also found hyperphosphorylation of tau at all three timepoints. In spite of this pathology, we did not find any hippocampal-dependent cognitive impairment in rats overexpressing human tau. These results provide evidence of AAV-htau as a progressive model of tauopathy pathology to study changes in phosphorylation status and neuronal cell death that might precede cognitive impairment. Full article
(This article belongs to the Special Issue Experimental Systems to Model Aging Processes)
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17 pages, 9284 KB  
Article
Baseline Analysis of Serotype-Specific IgG Antibody Levels for 13-Valent Pneumococcal Conjugate Vaccine in Healthy Chinese Individuals: A Multicenter Retrospective Study
by Gang Shi, Hong Li, Lina Guo, Lin Yuan, Jingjing Chen, Bin Li, Jinbo Gou, Weiyan Yin, Shuquan Luo, Jing Ti, Mengqi Duan, Fang Cao, Xiao Xu and Bin Wang
Vaccines 2025, 13(8), 847; https://doi.org/10.3390/vaccines13080847 - 10 Aug 2025
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Abstract
Background/Objectives: The immunogenicity of Streptococcus pneumoniae vaccines is commonly evaluated by assessing the fold increase or proportions exceeding 0.35 μg/mL in serotype-specific IgG antibody levels post-vaccination. Establishing baseline antibody levels in unvaccinated populations is therefore essential for defining serological thresholds and understanding naturally [...] Read more.
Background/Objectives: The immunogenicity of Streptococcus pneumoniae vaccines is commonly evaluated by assessing the fold increase or proportions exceeding 0.35 μg/mL in serotype-specific IgG antibody levels post-vaccination. Establishing baseline antibody levels in unvaccinated populations is therefore essential for defining serological thresholds and understanding naturally acquired immunity. This study aimed to assess the seroprevalence and baseline levels of IgG antibodies specific to 13 pneumococcal capsular polysaccharide serotypes in healthy infants and young children across multiple regions of China from 2016 to 2023, supporting evidence-based PCV13 vaccination strategies. Methods: IgG concentrations for 13 serotypes (1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F) were measured in unvaccinated individuals using the WHO-recommended ELISA. Univariate and multivariate analyses were applied to evaluate regional, age, and gender effects on baseline antibody levels. Results: GMCs for serotypes 6B, 14, 19A, and 19F exceeded 0.35 μg/mL, with 14 being the highest (1.64 μg/mL) and serotypes 3 and 4 the lowest. Significant regional variation (p < 0.001) and a U-shaped age trend were observed, with the lowest being at 7–11 months (p = 0.003). Conclusions: Baseline IgG levels varied by region and age. No significant gender differences were observed, and overall antibody levels were higher in the southern region. Full article
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