Search Results (191)

Background: Humoral immune responses to SARS-CoV-2 are well documented, yet the immunopathogenic mechanisms distinguishing severe from critical disease remain incompletely defined, particularly in Middle Eastern populations. We investigated antibody responses across levels of clinical severity in a Saudi Arabian cohort. Methods: In this multicentre study, we analysed 406 participants stratified into five clinical groups: controls, asymptomatic, mild, severe, and critically ill requiring intensive care unit (ICU) admission. SARS-CoV-2-specific IgG and IgM levels were quantified alongside surrogate ACE2-RBD neutralisation activity. Associations between humoral markers, demographic factors, comorbidities, and disease severity were assessed. Results: SARS-CoV-2-specific IgG and IgM levels differed significantly across disease severity groups (p < 0.001), with higher levels observed in groups with greater clinical severity. No significant difference in IgG or IgM levels was observed between the severe and ICU groups (IgG p = 0.384; IgM p = 0.768). While binding antibody levels were associated with severity, surrogate ACE2-RBD neutralising activity did not differ significantly across groups (p = 0.209). Increasing age (χ² = 44.5) and the presence of comorbidities (χ² = 31.9) were associated with more severe clinical categories, whereas sex was not. Conclusions: These findings suggest that antibody levels provide useful information about exposure and immune activation, but antibody quantity alone does not fully explain the transition from severe to critical disease. The results support interpreting serological measures alongside clinical factors such as age and chronic illness. Full article

Rare genetic disorders of the central nervous system (CNS) remain some of the most complex and challenging diseases to treat for several reasons. Targeting the CNS, especially the brain, presents one of the greatest obstacles in gene therapy using adeno-associated virus (AAV) vectors. Although various AAVs have been identified for their ability to transduce different cells in the CNS, their effectiveness and efficiency are significantly limited by the presence of neutralising antibodies (NAbs) and restricted cargo capacity. Despite these challenges, our understanding of AAV structure and technological advances continue to enable researchers to develop innovative strategies that have resulted in groundbreaking, FDA-approved therapeutic products now available for Leber congenital amaurosis (LCA) (Luxturna^®), spinal muscular atrophy (SMA) (Zolgensma^®), and the two recent gene therapy products for aromatic L-amino acid decarboxylase (AADC) deficiency, Kebilidi^® and Upstaza^®, which currently hold FDA and EMA approval, respectively. This review aims to highlight recent advances in the field of AAV gene therapy for neurological disorders, identify research gaps, and suggest areas for future investigation to enable potential breakthroughs particularly in neurodegenerative, neurodevelopmental, and neuromuscular disorders. We foresee that more tissue- and cell-specific AAV vectors designed using AI-powered platforms will emerge to precisely and efficiently target specific brain regions, transforming how CNS disorders are treated. Full article

Type I interferons (IFN-I), including IFN-α, IFN-β, and IFN-ω, are central to antiviral defence and immune regulation. Autoantibodies targeting IFN-I (anti-IFN-I AAbs) have emerged as key pathogenic factors in severe coronavirus disease 2019 (COVID-19) and are detectable in systemic lupus erythematosus (SLE), a prototypic IFN-driven autoimmune disease. Here we compare the prevalence and clinical impact of anti-IFN-I autoantibodies (Aabs) in COVID-19 and SLE based on a structured review of 53 studies from 2014 to 2025 and highlight the clinical associations and therapeutic opportunities presented by these autoantibodies. In COVID-19, neutralising anti-IFN-α and/or anti-IFN-ω AAbs were consistently associated with severe disease and impaired antiviral responses, particularly in older male populations. In SLE, anti-IFN-α AAbs were variably detected; neutralising antibodies were associated with reduced interferon gene signatures in some cohorts but inconsistent correlations with disease activity. Therapeutically, anti-IFN-I AAbs in COVID-19 may inform risk stratification and early antiviral strategies, whereas in SLE, IFN-α blockade, including IFN-α kinoid vaccination, demonstrates modulation of IFN signatures but variable clinical benefit. Notably, these findings reveal an immunological paradox: the same neutralising mechanism that impairs antiviral defence in COVID-19 may attenuate chronic IFN-driven inflammation in SLE. Taken together, anti-IFN-I AAbs exert context-dependent effects: pathogenic in acute viral infection yet potentially modulatory in chronic IFN-driven autoimmunity. Prospective longitudinal studies are required to further clarify their translational utility and long-term clinical impact. Full article

Saxitoxin (STX) is one of the most potent natural neurotoxins known and is the only marine toxin to be declared a chemical weapon. In both marine and freshwater systems filter feeding organisms can accumulate saxitoxin and human consumption of toxin-contaminated food can result in paralytic shellfish poisoning. Here we highlight for the first time a human cell-based assay for the detection and neutralisation of STX activity on an automated patch clamp (APC) system. We demonstrate that a human embryonic kidney (HEK) cell line expressing human Nav1.6 can rapidly and sensitively detect the presence of a range of sodium ion channel blockers including STX. The use of neutralising monoclonal antibody GT13-A and/or saxiphilin was found to confer specificity to the assay by being able to dissociate between STX (along with closely related analogues) and tetrodotoxin. Finally, the application of the functional assay for the detection of STX in complex samples was evaluated during an international exercise led by the Organisation for the Prohibition of Chemical Weapons (OPCW). The neutralisation of STX activity in blinded samples enabled the indirect detection of the toxin in the relevant samples and provided an alternative orthogonal technique to corroborate the findings of liquid chromatography–mass spectrometry (LC-MS). Collectively this work demonstrates the significant potential for functional assays in the analysis of samples suspected of being contaminated with STX and related sodium ion channel targeting toxins; complementing traditional direct identification methods such as high-performance liquid chromatography with fluorescence detection (HPLC-FLD), LC-MS or enzyme-linked immunosorbent assay (ELISA). Full article

The rapid expansion of the golden jackal (Canis aureus) across Eastern Europe has reshaped mesocarnivore communities, with potential influence on the dynamics of zoonotic disease. In Romania, where both Trichinella spp. and rabies remain public health concerns, updated data on wildlife reservoirs are essential. This study aims to provide an integrated assessment of Trichinella prevalence and rabies virus-neutralising antibody (RVNA) profiles in 134 wild canids (96 golden jackals and 38 red foxes, Vulpes vulpes) from northwestern Romania (August 2025–January 2026). Trichinella larvae were detected using the artificial digestion method, and infection intensity was expressed as larvae per gram. Rabies serology was performed using a commercial ELISA kit, with 0.5 IU/mL considered the protective threshold. Trichinella prevalence was significantly higher in foxes (78.9%) in comparison with jackals (60.4%), with similar larval burdens in both species. More than half of the individuals in both species exhibited RVNA titers below the protective threshold, indicating heterogeneous immunity levels in the population. No significant age- or sex-related differences in seroconversion were observed. These findings confirm intense sylvatic circulation of Trichinella spp. and highlight potential immunity gaps in wildlife rabies control. The results support the need for integrated, multi-pathogen surveillance and explicit inclusion of the golden jackal in disease monitoring and management strategies. Full article

Background: Porcine epidemic diarrhoea virus (PEDV) is a highly contagious pathogen causing severe diarrhoea and high mortality in neonatal piglets. Methods: In this study, consensus sequences encoding the N-terminal domain of spike subunit 1 (S1-NTD) and nucleocapsid (N) protein of PEDV were cloned into a eukaryotic expression vector pJHL204 and transformed into an attenuated Salmonella Typhimurium strain JOL2500. Antigen expression was confirmed by Western blot and immunofluorescence analyses. The recombinant strains were evaluated in vivo for safety, persistence, and immunogenicity. Immunogenicity was characterised by measuring antibody response, virus neutralising assays, cytokine profiling, and flow cytometric analysis of T cell subpopulation. Protective efficacy against salmonellosis in dams and passive transfer of neutralising antibodies to suckling mice were evaluated. Results: Vaccinated mice exhibited no adverse effects or bacterial persistence in major organs, confirming the vaccine’s safety. Immunisation elicited robust PEDV- and Salmonella-specific humoral and cell-mediated immune responses. Upon Salmonella challenge, vaccinated mice showed significantly reduced bacterial loads in splenic tissues. Furthermore, vaccinated dams and their offspring induced detectable anti-PEDV neutralising antibodies, indicating successful passive antibody transfer. Conclusion: Our findings indicate that the designed vaccine constructs provide a promising platform for inducing multifaceted immuno-protectivity against PEDV and salmonellosis. Full article

Complement and pathogenic antibodies act independently and together to mediate the pathology of many autoimmune diseases. To address these drivers of disease, we generated a monoclonal antibody (mAb), CSL305, that binds and inhibits both complement and the neonatal Fc (fragment crystallizable) receptor FcRn. The fragment antigen binding (Fab) portion of CSL305 was engineered to bind both human C2 (huC2) zymogen and the active fragment huC2b to inhibit the classical and lectin complement pathways in vitro, and C3b deposition on primary lung endothelial cells using a 3-dimensional microvascular model system. Engineering of a triple amino acid mutation (“YPY” motif) into the Fc region of CSL305 increased its affinity to FcRn at both acidic and neutral pH, allowing it to also act as a potent FcRn antagonist. Intracellular trafficking experiments demonstrated that CSL305, but not the wild-type (WT) mAb lacking the YPY motif, was able to block immunoglobulin G (IgG) recycling in vitro. The generation of a high resolution 2.6Å crystal structure of CSL305 Fab region bound to huC2b showed that the epitope lies directly over the huC2b catalytic triad, providing evidence of its complement mechanism of action as a neutralising mAb. Early pharmacokinetic (PK)/pharmacodynamic (PD) studies using CSL305 in cynomolgus monkeys demonstrated both complement inhibition and FcRn antagonism in vivo, with reductions in complement classical pathway activity and endogenous IgG observed following single intravenous (IV) administration. CSL305 thus represents a dual-functional mAb as a potential therapeutic candidate. Full article

Age-related macular degeneration (AΜD) remains a leading cause of irreversible vision loss. Ιn neovascular AΜD (nAΜD), frequent intravitreal anti-VΕGF injections create substantial treatment burden, while approved therapies for geographic atrophy (GA) provide modest slowing of progression. Ocular gene therapy aims to achieve sustained intraocular expression of therapeutic proteins after a single administration. Τhis review summarises the biological rationale, vector platforms, and delivery routes relevant to AΜD, with emphasis on adeno-associated virus (AAV) systems, capsid engineering, and compartment-specific administration (intravitreal, subretinal, and suprachoroidal). We synthesise the clinical landscape for sustained anti-VΕGF expression approaches in nAΜD and complement-modulating strategies for GA, and highlight how trials increasingly prioritise injection-burden reduction, anatomical endpoints, and biomarkers of target engagement. Κey challenges include intraocular inflammation and neutralising antibodies (particularly with intravitreal dosing), variability and durability of transgene expression, surgical risks associated with subretinal delivery, and practical constraints related to manufacturing scale, cost, and long-term safety surveillance for non-removable therapies. Overall, gene therapy offers a plausible route towards durable, mechanism-targeted AΜD management, but its clinical role will depend on robust controlled trials and multi-year follow-up. Full article

Monkeypox virus (MPXV) is a zoonotic Orthopoxvirus responsible for Monkeypox (Mpox), historically associated with sporadic zoonotic transmission but increasingly characterised by sustained human-to-human spread. While vaccinia-based vaccination is known to confer cross-protection against MPXV, the durability of such immunity over a human lifetime remains incompletely characterised. Here, we assessed humoral and cellular immune responses to MPXV in octogenarians and nonagenarians vaccinated against smallpox during childhood. Twenty-three adults aged 79–94 years (median 83), who self-reported childhood vaccinia vaccination between 1925 and 1940, were recruited. MPXV-specific antibody responses were evaluated using ELISA, targeting homologous vaccinia and MPXV proteins, and live-virus neutralisation assays. Cellular immunity was assessed by IFN-γ ELISpot following stimulation with peptide pools derived from highly conserved vaccinia antigens. Responses were also obtained from younger, recently MVA–BN-vaccinated and unvaccinated control donors. All historically vaccinated participants exhibited MPXV-reactive IgG responses, with antibody binding and neutralisation levels comparable to recently vaccinated individuals. Functional neutralising activity against MPXV was detected in all donors, with ≥50% neutralisation observed in 78% of participants. Antibody concentrations correlated strongly with neutralisation capacity. T-cell responses were detectable in all historically vaccinated donors, most prominently against the major core protein A10L, although reduced magnitudes were observed in participants over 90 years of age. No MPXV-specific humoral or cellular responses were detected in unvaccinated controls. These findings demonstrate that childhood vaccinia vaccination induces durable humoral and cellular immunity against MPXV persisting for over seven decades. Historical smallpox vaccination status may therefore remain a relevant determinant of protection against Mpox. Full article

Bacillus anthracis has three main virulence factors: an extracellular capsule and two binary toxins (lethal toxin—consists of a lethal factor and a protective antigen, and edema toxin—consists of an edema factor and a protective antigen). In the Russian Federation, the epidemiological situation regarding anthrax infection remains unfavorable. In the late stages of an anthrax infection, antibiotic therapy becomes ineffective and the patient dies within 24 h as a large amount of lethal toxin accumulates in the patient’s blood. Antibodies capable of neutralising lethal toxin (LT) can be an effective treatment for these patients. The objective of the study was to construct a chimeric monoclonal antibody targeting the protective antigen of the LT and to elucidate its mechanism of toxin neutralization. In this work, a chimeric monoclonal antibody (xi1E10) directed against the protective antigen was successfully produced. Both in vitro and in vivo experiments demonstrated the capacity of xi1E10 to neutralize lethal toxin. Confocal microscopy revealed that xi1E10 effectively suppresses the formation of a functional pore, thereby blocking the translocation of the lethal factor into the cytosol. These findings indicate that the monoclonal antibody xi1E10 represents a promising candidate for the development of a therapeutic drug. Full article

Background: Fasciola hepatica (F. hepatica) infection reduces antibody avidity to foot-and-mouth disease virus (FMDV) vaccination in cattle despite preserved total antibody levels. However, its effect on vaccine-induced immunity in water buffaloes (Bubalus bubalis), which contribute to FMDV maintenance in endemic settings, has not been investigated. Objectives: To evaluate the effect of natural F. hepatica infection on the magnitude and functional quality of the FMDV–specific antibody response in buffaloes under field conditions. Methods: Two buffalo herds (n = 50 each) were classified by infection status using coproparasitological analysis and serology. All animals were vaccinated within the national foot-and-mouth disease control programme, with the last dose administered 264 days before sampling. Serum neutralising titres, total antibodies by liquid-phase blocking ELISA, IgG levels, and IgG avidity to the A24/Cruzeiro vaccine strain were determined. Results: F. hepatica-infected buffaloes exhibited consistent decreases across all vaccine-induced antibody parameters. Neutralising titres were reduced approximately two-fold, IgG avidity by about 38 percent, IgG levels by about 36 percent, and liquid-phase blocking ELISA titres by about 1.6-fold compared with non-infected animals. Conclusions: This study provides the first field evidence that fasciolosis is associated with changes in the magnitude and quality of vaccine-induced humoral responses following FMDV vaccination in water buffaloes, indicating that F. hepatica infection may influence the interpretation of post-vaccination serological monitoring in this species under endemic field conditions. Full article

Background: Streptococcus equi subspecies equi (S. equi) is the cause of strangles, one of the most prevalent diseases of horses worldwide. The disease is characterised by fever and the formation of abscesses in the lymph nodes of the head and neck, which can restrict the airway. A multicomponent subunit vaccine, Strangvac, has been shown to effectively reduce clinical signs of strangles and to reduce its incidence. Objective: The aim of this study was to determine the immune response against the immunoglobulin-cleaving endopeptidase IdeE, a key protective component within the vaccine and the ability of antibodies to neutralize the proteolytic activity of IdeE. Methods: An in vitro assay was developed to measure the functional inhibition of recombinant IdeE by horse sera pre- and post-vaccination. The IdeE-neutralising titres were compared to the corresponding IdeE-specific antibody titres measured by iELISA (indirect Enzyme-Linked Immunosorbent Assay). Results: A significant IdeE-specific antibody response in blood serum collected from ponies was induced after Strangvac vaccinations. Concomitantly, significant increases in the neutralising activity of IdeE occurred, persisting for at least 12 months post-second vaccination. IdeE-neutralising activity was further increased significantly after a third vaccination, even when the third dose was administered 12 months after the second dose, demonstrating that immunological memory to the vaccine persisted for 12 months. There was a significant correlation between the IdeE-neutralising activity of blood sera and the level of IdeE-specific antibodies. Conclusions: These data provide insights into one potential mechanism by which this vaccine protects Equids against or during S. equi infection. Full article

Background: In the Kingdom of Saudi Arabia, various COVID-19 vaccines were administered during the pandemic. However, region-specific real-word comparative data on their immunogenicity remain limited. This study aimed to assess the serological responses to Pfizer-BioNTech (BNT162b2), Moderna (mRNA-1273), and AstraZeneca (ChAdOx1 nCoV-19) vaccines in a diverse population living in KSA. Methods: This observational study included 236 adults recruited from vaccination sites in Riyadh. Participants provided serum samples at predefined intervals: before the first dose, after the first dose, after the second dose, and post-vaccination infection (if applicable). IgG and neutralising antibodies were quantified using ELISA assays. Demographic and vaccination data, and their associations with antibody responses, were evaluated. Results: At baseline, 75.4% of participants were positive for SARS-CoV-2 IgG, suggesting high prior exposure. Marked incremental increases in IgG levels were observed after each vaccine dose. Both Moderna and Pfizer elicited stronger responses, with Pfizer inducing the strongest early response and Moderna achieving the highest overall titres. Among IgG-positive individuals, neutralising antibodies were detected in 98.1%. There were no statistically significant differences by age or gender, although males tended to show higher mean titres. Heterologous vaccine schedules induced comparable or enhanced immunogenicity relative to homologous schedules, supporting their use in flexible immunisation strategies. Conclusions: All COVID-19 vaccines administered in Saudi Arabia elicited robust antibody responses, particularly the mRNA-based vaccines. Our findings support their continued use and justify varied vaccination approaches, including mix-and-match booster strategies, to enhance community immunity. Full article

The 2022 global mpox outbreak, caused by clade IIb of the monkeypox virus (MPXV), prompted emergency use authorisation of the Modified Vaccinia Ankara–Bavarian Nordic (MVA-BN) vaccine, previously approved for smallpox prevention. Understanding immune responses to the MVA-BN vaccine is critical to inform both current and future mpox vaccine policy, particularly amid reports of breakthrough infections in vaccinated persons, uncertainty about the durability of vaccine-induced protection, and the emergence of further outbreaks of mpox from different viral clades, including the clade I-driven public health emergency of international concern. MVA-BN elicits binding and neutralising antibody, memory B cells, and T cell responses. Immune responses vary by host factors, prior orthopoxvirus exposure, and dosing regimens. While seroconversion is generally robust, circulating antibody titres often wane rapidly, particularly in vaccinia-naïve and/or immunocompromised individuals, including people with HIV. Vaccine-induced neutralising antibody responses to MPXV are frequently lower than to vaccinia virus, and their role in protection remains ill-defined. In contrast, T cell responses appear more sustained and may support long-term immunity in the absence of persistent antibody titres. This narrative review synthesises current evidence on the immunogenicity and durability of MVA-BN vaccination, highlights challenges in assay interpretation, and outlines key research priorities, including the need to explore correlates of protection, booster strategies, and next-generation vaccine design. Full article

We aimed to explore SARS-CoV-2 evolution during in vitro neutralisation using next generation sequencing, and to determine whether sera from individuals immunised with two doses of the Pfizer-BioNTech vaccine (BNT162b2) were as effective at neutralising the variant of concern (VOC) Delta (B.1.617.2) compared to the earlier lineages Beta (B.1.351) and wild-type (A.2.2) virus. Using a live-virus SARS-CoV-2 neutralisation assay in Vero E6 cells, we determined neutralising antibody titres (nAbT) against three SARS-CoV-2 strains (wild type, Beta, and Delta) in 14 participants (vaccine-naïve (n = 2) and post-second dose of BNT162b2 vaccination (n = 12)), median age 45 years [IQR 29–65]; the median time after the second dose was 21 days [IQR 19–28]. The determination of nAbT was based on cytopathic effect (CPE) and in-house quantitative reverse transcriptase real-time quantitative polymerase chain reaction (RT-qPCR) to confirm SARS-CoV-2 replication. A total of 110 representative samples including inoculum, neutralisation breakpoints at 72 h, and negative and positive controls underwent genome sequencing. By integrating live-virus neutralisation assays with deep sequencing, we characterised both functional antibody responses and accompanying viral genetic changes. There was a reduction in nAbT observed against the Delta and Beta VOC compared with wild type, 4.4-fold (p ≤ 0.0006) and 2.3-fold (p = 0.0140), respectively. Neutralising antibodies were not detected in one vaccinated immunosuppressed participant and the vaccine-naïve participants (n = 2). The highest nAbT against the SARS-CoV-2 variants investigated was obtained from a participant who was vaccinated following SARS-CoV-2 infection 12 months prior. Limited consensus level mutations occurred in the various SARS-CoV-2 lineage genomes during in vitro neutralisation; however, consistent minority allele frequency variants (MFV) were detected in the SARS-CoV-2 polypeptide, spike (S), and membrane protein. Findings from countries with high COVID-19 incidence may not be applicable to low-incidence settings such as Australia; as seen in our cohort, nAbT may be significantly higher in vaccine recipients previously infected with SARS-CoV-2. Monitoring viral evolution is critical to evaluate the impact of novel SARS-CoV-2 variants on vaccine effectiveness, as mutational profiles in the sub-consensus genome could indicate increases in transmissibility and virulence or suggest the development of antiviral resistance. Full article