Search Results (517)

Secondary dengue infections are often linked to more severe clinical outcomes, yet pre-existing antibodies may exert either protective or pathogenic effects. To evaluate the role of acute-phase dengue antibodies in pediatric dengue, we analyzed clinical and laboratory features, viremia, and antibody profiles in children infected with DENV-1. We conducted a retrospective study of patients under 18 years diagnosed with DENV-1 in Salta, Argentina. Viremia was quantified by real-time RT-PCR; acute-phase IgG antibodies (within 7 days from symptom onset) against DENV, DENV-1, and DENV-NS1 were measured by immunoassays, and neutralizing antibodies by plaque reduction neutralization tests. Among 151 patients (median age 12 years), 62% presented dengue with warning signs and one case progressed to severe dengue. Viremia was higher in probable primary infections than in probable secondary infections and did not correlate with disease severity. Probable secondary infections were characterized by acute-phase antibody profiles that did not associate with DENV viremia. Age-stratified analyses revealed that adolescents exhibited higher viremia levels than younger children in probable primary infections, while viremia levels were comparable across age groups in probable secondary infections. Furthermore, children younger than 10 years displayed acute-phase antibody levels similar to those of adolescents. In adolescents with probable secondary infections, anti-DENV and anti-DENV-1 IgG were inversely correlated with platelet counts, whereas neutralizing and anti-DENV-NS1 antibodies showed no association. Collectively, these findings indicate that probable secondary DENV infections in our pediatric cohort were characterized by acute-phase antibodies that were not associated with viremia control, and that in adolescents, anti-DENV and anti-DENV-1 IgG antibodies likely associated with platelet depletion. These results highlight important implications for vaccine design, underscoring the need for vaccines that elicit strong neutralizing responses while minimizing cross-reactivity and the risk of antibody dependent enhancement. Full article

Outbreaks of avian infectious bronchitis virus (IBV) often occur in vaccinated flocks. The antibody-dependent enhancement (ADE) has been proposed as a potential mechanism underlying coronavirus vaccine failure. However, this hypothesis has yet to be substantiated in flocks. This study demonstrates ADE occurrence in IBV (gamacoronavirus) in vitro and in vivo. Using the SPF chicken host model, primary infection with an O-glycosylation-modified attenuated strain enhanced pathogenesis upon secondary homologous/heterologous virulent challenge, increasing morbidity/mortality (≥30%), pathological lesions, and viral loads. Notably, sequentially attenuated infections also induced ADE, suggesting live attenuated vaccine risks. The immune serum raised against the O-glycosylation-modified attenuated strain was also pre-mixed with the challenge strain, and the mixtures were then inoculated into target cells, non-susceptible macrophage cells, or a co-culture of both cell types. The serum-virus complexes replicated poorly in macrophages, yet immune cells amplified the expression of inflammatory factors and ADE-mediated viral replication in target cells, indicating a significant promoting role of immune cells in this process. The concentrations of complement component C3 and neutralizing antibodies in the immune serum were also measured, and results showed that the induction of this ADE is associated with high complement component C3 and low neutralizing antibody titers. These findings highlight risks for vaccines and antibody-based therapeutic strategies of coronavirus infection. Full article

Background: Primary cells derived from connective tissues contain mesenchymal stem/stromal cell (MSC)–like progenitors with chondrogenic potential relevant for cartilage repair. However, donor- and tissue-specific variability and the lack of robust, high-content analytical methods limit their translational use. Objectives: This study aimed to develop and optimize a high-content imaging workflow for quantitative evaluation of chondrogenesis in three-dimensional (3D) pellets derived from primary cells. Methods: Primary human cells isolated from cartilage were chondrogenically differentiated in vitro. A systematic optimization of immunofluorescence staining parameters was performed, including staining platform, enzymatic matrix digestion, non-specific site blocking, membrane permeabilization, and nuclear counterstaining. Type II collagen was detected using an Alexa Fluor 488–conjugated antibody, and pellets were analyzed using high-content non-confocal imaging. Fluorescence intensities were adjusted to the pellet area to account for size-dependent effects. Results: Staining directly in imaging plates enabled streamlined high-content analysis. Controlled pepsin-mediated matrix digestion markedly enhanced antibody penetration, while excessive digestion compromised pellet integrity. Extended bovine serum albumin blocking improved type II collagen signal intensity and homogeneity. Triton X-100 permeabilization increased detection sensitivity but occasionally induced structural disruption in weakly organized control pellets. The optimized protocol enabled clear discrimination between chondrogenic pellets and controls, with approximately threefold higher type II collagen signal in chondrogenic samples. Conclusions: This study establishes a high-content imaging–based workflow for quantitative assessment of 3D chondrogenesis from primary cells. The approach provides a rapid, scalable platform with direct relevance for in vitro screening, potency testing, and quality control in cartilage-oriented advanced therapy development. Full article

Background: The COVID-19 pandemic exposed critical gaps in pandemic preparedness and highlighted the need for vaccine platforms capable of rapid adaptation. Outer membrane vesicle (OMV)-based platforms utilizing vesicles derived from genetically detoxified Neisseria meningitidis serogroup B (Nm-nOMV) represent a promising plug-and-play approach. Methods: This Phase I, first-in-human, randomized, double-blind, placebo- and OMV-controlled trial, evaluated safety, tolerability, and immunogenicity of intranasally administered OMVs combined with SARS-CoV-2 Spike protein in healthy SARS-CoV-2 seropositive adults aged 18–55 years. Forty participants were enrolled across two cohorts: a low-dose cohort receiving 140 μg OMV/70 μg Spike (OMV + Spike, n = 13; OMV alone, n= 3; Placebo, n = 5) and a high-dose cohort receiving 280 μg of OMV/140 μg of Spike (OMV + Spike, n = 13; OMV alone, n = 3; Placebo, n = 3), administered on Days 1 and 22. Safety was assessed through adverse events, vital signs, laboratory parameters, ECG, and pulse oximetry. Immunogenicity was evaluated via systemic SARS-CoV-2 neutralizing antibodies, antigen-specific antibodies (IgG and IgA), and mucosal antibodies (IgA in nasal wash). Results: Intranasal administration of OMVs combined with SARS-CoV-2 Spike protein was safe, well-tolerated, and immunogenic. No serious adverse events were reported, and adverse events were predominantly mild and transient. Dose-dependent increases in systemic and mucosal immune responses were observed, with statistically significant enhanced serum IgG and nasal wash IgA antibodies in the high-dose group. Conclusions: The current clinical data confirm key aspects of the preclinical profile, which demonstrate the potential of the Nm-nOMV platform as a strong adjuvant for mucosal vaccines. These findings support the broader application of the Nm-nOMV vaccine platform in pandemic preparedness. Full article

Background: Antibody–drug conjugates (ADCs) have evolved from early heterogeneous constructs into a mature therapeutic platform with exponential clinical relevance. This review highlights recent advances in ADC design and development, with emphasis on antigen selection, antibody engineering, linker and payload innovation, site-specific conjugation, clinical translation, toxicity, resistance, and emerging data-driven approaches. Methods: The review draws on the literature published from 2019 to the recent clinical and regulatory developments relevant to approved and late-stage ADCs, emphasizing the advances in target biology, antibody formats, linker chemistry, payload classes, conjugation technologies, developability assessment, and computational or artificial intelligence-assisted design strategies. Results: ADC development has evolved with improved target selection, enhanced internalization and tumor selectivity, and the use of engineered, bispecific, biparatopic, and fragment-based antibody formats. Linker and payload innovation has expanded beyond traditional microtubule inhibitors to include topoisomerase I inhibitors, DNA-damaging agents, and emerging dual-payload or non-cytotoxic strategies. Site-specific conjugation and improved control of drug-to-antibody ratio have increased stability, pharmacokinetic performance, and manufacturability. Clinically, ADCs are being used across a broader range of malignancies and treatment settings, although toxicities and resistance mechanisms remain an important limitations. Computational methods and artificial intelligence are increasingly being explored for target discovery, molecular optimization, toxicity prediction, and model-informed clinical development. Conclusions: ADCs are transitioning toward a more integrated, design-driven platform in which antigen biology, antibody format, chemistry, and computational prediction are jointly optimized. Future progress will depend on improved standardization, biomarker-guided development, and interdisciplinary approaches to enhance its therapeutic index and expand its applications beyond oncology. Full article

Mucosal immunity in the respiratory tract provides the first line of defense against airborne pathogens, yet most current vaccines fail to induce strong and durable immune responses at these sites. Respiratory viruses, including respiratory syncytial virus (RSV), influenza viruses, and coronaviruses, remain major global health threats, in part due to their ability to evade long-term mucosal protection. Although systemic vaccination generates robust circulating immunity, it induces limited local responses, particularly secretory immunoglobulin A (IgA), which is critical for preventing viral entry and transmission at the airway surface. The mechanisms regulating B cell responses within the airway mucosa are not fully understood. B cell–activating factor (BAFF), a member of the tumor necrosis factor (TNF) superfamily, has emerged as an important context-dependent regulator of mucosal B cell immunity. BAFF is produced by airway epithelial cells and multiple myeloid populations, including dendritic cells and neutrophils, and is rapidly induced during respiratory viral infection through type I interferon–dependent pathways. Functionally, BAFF supports B cell survival, differentiation, and class-switch recombination, promoting the generation of antibody-secreting plasma cells and enhancing IgA production. In the lung, these effects align with early, intermediate, and late stages of the response, supporting initial local antibody production, the formation of inducible bronchus-associated lymphoid tissue (iBALT), and the development of tissue-resident memory B cells that sustain long-term immunity. Although BAFF plays an essential role in mucosal immunity, its activity requires tight regulation to maintain immune balance. Current evidence supports BAFF as a promising immunomodulatory component and highlights its potential as an adjuvant platform for enhancing mucosal vaccine efficacy, warranting further investigation as a potential adjuvant in this context. Full article

Food contamination by Aflatoxin M1 and Atrazine remains a critical food-safety concern, requiring sensitive detection methods that can operate reliably in complex matrices. Here, we report an AI-assisted antibody-functionalized electrochemical sensing platform for the detection and classification of Aflatoxin M1 and Atrazine across corn, corn flour, and protein matrices. The sensor used analyte-specific antibodies immobilized on an electrochemical electrode surface, where target binding produced measurable changes in the interfacial electrochemical response. Sensor performance was evaluated using cyclic voltammetry, coulometry, and electrochemical impedance spectroscopy (EIS), with EIS providing strong frequency-dependent signatures for concentration-dependent analysis. Spike-and-recovery studies further demonstrated the applicability of the platform in food-matrix conditions. To improve interpretation of complex electrochemical signals, full-spectrum EIS features were integrated with machine learning models for concentration-level classification into low, mid, and high groups. The AI workflow achieved an overall classification accuracy of 93.33%, with 96.67% specificity, 93.44% PPV, 96.66% NPV, and 0.982 AUC for Atrazine, and 96.70% specificity, 93.38% PPV, 96.67% NPV, and 0.987 AUC for Aflatoxin M1. In addition, analyte classification between Aflatoxin M1 and Atrazine reached 97.4% accuracy and 0.994 ROC-AUC. Overall, this work demonstrates a matrix-aware electrochemical immunosensing strategy enhanced by AI-based signal interpretation for food contaminant detection. Full article

Radix pseudostellariae saponins (RPS) enhance immune responses in animals; however, the regulatory mechanisms of these effects remain unclear. This study observed that 14 days post-intranasal immunization with RPS and a Mycoplasma gallisepticum-attenuated vaccine (MGAV), MGAV-specific antibody titers were significantly increased in the blood, and chemokine (C-C motif) ligand 5 (CCL5) messenger RNA expression was significantly increased in the trachea and blood of chickens. Transcriptomic analysis demonstrated that RPS treatment significantly upregulated specific Kyoto Encyclopedia of Genes and Genomes pathways, notably the cytokine–cytokine receptor interaction pathway, which is linked to immune cell migration and involves chemokine receptor chemokine (C-C motif) receptor 4 (CCR4). This finding was corroborated at the protein level by immunohistochemical evidence showing increased CCL5 expression in tracheal tissue. In vitro studies showed that RPS enhanced the phagocytic capacity of RAW264.7 macrophages against ovalbumin, with immunofluorescence revealing time-dependent and dose-dependent CCL5 in these cells. Transwell and scratch-healing assays confirmed that RPS promoted this migration of both RAW264.7 cells and CCR4-positive lymphocytes. Collectively, the findings revealed that RPS modulated the activation, chemotaxis, and migration of macrophages and lymphocytes and is associated with the promotion of the CCL5/CCR4 signaling axis, providing novel evidence for the immune-enhancing effects of RPS by enhancing immunogenicity. Full article

Dengue Virus (DENV) circulates as four antigenically distinct serotypes whose dominance fluctuates over time in many endemic regions, a phenomenon known as serotype shift that is frequently associated with large outbreaks and increased disease severity. This review, through a synthesis of epidemiological, virological, immunological, entomological, and environmental evidence, observes that serotype shift likely arises from the interaction of multiple determinants rather than solely from viral evolution, with population immunity playing a central role. The accumulation of serotype-specific herd immunity, together with short-lived cross-protection and Antibody-Dependent Enhancement (ADE), reshapes population susceptibility and creates ecological space for heterologous serotypes with higher transmission potential. The synthesis of global dengue studies indicates that these immune dynamics interact with viral genetic diversity, vector competence, climate variability, and human factors such as demography, socioeconomic status, population density and mobility to drive cyclical and sometimes abrupt changes in serotype dominance. Notably, the review indicates that serotype changes often precede or coincide with more clinical severity and patterns of outbreaks, with direct implications for the process of forecasting outbreaks, vaccine performance, and preparedness to respond with appropriate health measures. On the whole, this review confirms the opinion that the change of dengue serotype occurrence becomes a consequence of interconnected biological and ecological processes involved in the transmission of dengue serotype shifts in hyperendemic areas. Full article

Ranges of distribution of some orthoflaviviruses, including the Omsk hemorrhagic fever virus (OHFV) and the Powassan virus (POWV), have been identified in the range endemic for the tick-borne encephalitis virus (TBEV). In contrast to TBEV, no registered vaccine against OHFV and POWV is currently available. Nevertheless, recent studies have indicated that the anti-TBEV vaccine may offer partial protection against other orthoflaviviruses. The present study assesses OHFV and POWV infection in an experimental model on BALB/c mice one, three- and twelve-months post-immunization with inactivated TBE vaccine. The TBE vaccine was shown to provide long-term protection against OHFV and partial protection against POWV, even in the absence of specific antibodies, and without indications of antibody-dependent enhancement of infection. The neutralizing antibody titer for OHFV in vaccinated animals before and after the challenge with OHFV was similar to the titer of antibodies against the TBEV vaccine strain. Following immunization with anti-TBEV vaccine and subsequent inoculation of POWV, the levels of neutralizing antibodies against the TBEV vaccine strain was observed to be higher compared to those targeting POWV, especially during the initial phase of infection. Such cross-reactive antibodies have potential to pose a significant diagnostic challenge in cases where an infection is occurring simultaneously with an immune response to another virus. Full article

West Nile Virus (WNV) belongs to the orthoflavivirus genus and is part of the Flaviviridae family, which includes the Japanese encephalitis virus, Dengue virus, Zika virus, and yellow fever virus. WNV circulates among birds and mosquitoes, posing infection risks to humans and mammals. The significant rise in WNV’s geographic spread and infection rates over the past five decades has prompted urgent public health concerns, driving the need for accelerated vaccine research. The development of a vaccine for WNV infection presents several challenges, primarily due to the virus’s complex biology, the risk of cross-reactivity with other flaviviruses, safety concerns such as antibody-dependent enhancement (ADE), and the economic and logistical hurdles in vaccine production. Despite significant research efforts, no human vaccine has been approved, although several candidates are in various stages of development. The current review offers a comprehensive summary of the latest progress and the concomitant challenges in the development of vaccines. It also discusses the role of host–pathogen interaction, host immunity, viral immune evasion, and disease pathogenesis in facilitating the advancement of vaccines. Full article

Background: Rift Valley fever virus (RVFV) is a mosquito-borne zoonotic pathogen that has caused repeated epidemics across Africa and the Arabian Peninsula, posing a severe and growing threat to public health and livestock. Infection in ruminants causes high neonatal mortality and catastrophic abortion storms; human disease ranges from self-limiting febrile illness to hemorrhagic fever, encephalitis, and permanent blindness. No licensed human vaccines or specific antiviral therapeutics are available, creating an urgent unmet medical need. Methods: We systematically reviewed the peer-reviewed literature on RVFV neutralizing antibodies (NAbs), extracting and synthesizing data on antibody sources, epitope specificity, in vitro neutralizing potency, in vivo protective efficacy, and molecular mechanisms of action. Results: A growing body of work has identified potent NAbs from immunized rodents, rabbits, alpacas, non-human primates, and convalescent patients. These NAbs predominantly target the Gn and Gc envelope glycoproteins. Their mechanisms include blocking host receptor (LRP1) binding, preventing the pH-dependent conformational rearrangement of the Gn–Gc complex, and directly inhibiting viral membrane fusion. Lead candidates, such as RVFV-268 and RVFV-140, achieve sub-nanogram neutralization and confer robust protection in rodent models against lethal challenge, aerosol exposure, and vertical transmission. Bispecific antibodies and combination strategies further enhance potency and the genetic barrier to viral escape. Conclusions: Substantial progress has illuminated the epitope landscape and neutralization mechanisms of RVFV, yielding promising clinical candidates. Translational challenges remain, including viral immune escape, antibody thermostability, and the need for rigorous preclinical evaluation. Future efforts should prioritize structure-guided engineering, rational antibody combinations, and testing in clinically predictive animal models. Full article

Background: Antiphospholipid antibodies (aPLs) are essential for antiphospholipid syndrome (APS) diagnosis, which is based on clinical and laboratory parameters, including the detection of lupus-anticoagulant (LAC), anti-cardiolipin (aCL) and anti-β2-glycoprotein-I (aβ2-GPI) antibodies. The enzyme-linked immunosorbent assay (ELISA) is the reference methodology for classification criteria, although chemiluminescence immunoassays (CLIA) are more common in clinical practice. Methods: Since LAC reflects the functional activity of a large subset of antiphospholipids, through coagulation assays that enhance a phospholipid-dependent inhibitory effect, it has been used as a reference for assessing ELISA and CLIA reliability. Samples, separated into positive and negative LAC, were selected by CLIA detection in negative and positive IgG/IgM aCL and aβ2-GPI (cut-off > 20 U/mL). Results: The ELISA/CLIA comparison showed a 100% concordance in triple negative groups, highlighting an optimal analytical specificity; a higher concordance in the aβ2-GPI IgM-positive groups compared to positive aCL IgM (100% vs. 76% in LAC-positive groups; 82% vs. 71% in LAC-negative groups), as well as in aβ2-GPI IgM-negative groups compared to negative aCL IgM in LAC-positive groups (100% vs. 87.5%); and a massive concordance reduction in positive IgG aβ2-GPI and aCL groups (44% vs. 50% in LAC-positive groups; 4.8% vs. 4.5% in LAC-negative groups). Concordance increased in all groups with a higher CLIA cut-off (>50 U/mL). Conclusions: Although CLIA performances partly differed from ELISA, this does not preclude their use in APS diagnosis, which aims for higher sensitivity in detecting cases of disease. ELISA is confirmed to be more reliable for classification criteria that aim for high specificity to reduce false positives. Full article

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

Differentiation therapy holds significant potential for the treatment of multiple myeloma (MM). We previously identified that the aminopeptidase N (APN) inhibitor Bestatin promotes MM cell differentiation. Herein, we elucidate the underlying molecular mechanisms of this process. Utilizing MM1.S, U266, and RPMI-8226 cell lines, a combination of CCK-8 assays, flow cytometry, Wright–Giemsa staining, Western blotting, qRT-PCR, ELISA, APN enzymatic activity analysis, SA-β-gal staining, and bioinformatic analyses revealed elevated APN expression across all cell types. Bestatin treatment induced MM cell differentiation in a concentration-dependent manner, which was accompanied by the upregulation of the differentiation marker CD49e, increased immunoglobulin light chain secretion, elevated cellular senescence, and a concomitant suppression of cell proliferation and APN enzymatic activity. Mechanistically, Bestatin exerts its effects by downregulating the CD79B/BTK signaling pathway, thereby activating the downstream transcription factor STAT3. Consistent with this axis, direct inhibition of CD79B/BTK alone was sufficient to induce differentiation, while blockade of STAT3 completely abrogated the differentiation-promoting effect of Bestatin. The APN-neutralizing antibody (WM15) yielded consistent results with Bestatin, further validating this regulatory axis. Furthermore, both the CD79B/BTK inhibitor Ibrutinib and the STAT3 agonist GCDA potentiated the cytotoxicity of the clinical MM drug Ixazomib. Bestatin itself synergized with Ixazomib and enhanced the anti-proliferative effect of IL-6. In summary, our findings establish that the APN inhibitor Bestatin induces MM cell differentiation via the CD79B/BTK-STAT3 signaling axis. Targeting this pathway represents a promising strategy to enhance the efficacy of Ixazomib, providing a compelling rationale for novel combination therapies in MM. Full article