Search Results (804)

Multivalent lectin–glycan interactions (MLGIs) are vital for viral infection, cell-cell communication and regulation of immune responses. Their structural and biophysical data are thus important, not only for providing insights into their underlying mechanisms but also for designing potent glycoconjugate therapeutics against target MLGIs. However, such information remains to be limited for some important MLGIs, significantly restricting the research progress. We have recently demonstrated that functional nanoparticles, including ∼4 nm quantum dots and varying sized gold nanoparticles (GNPs), densely glycosylated with various natural mono- and oligo- saccharides, are powerful biophysical probes for MLGIs. Using two important viral receptors, DC-SIGN and DC-SIGNR (together denoted as DC-SIGN/R hereafter), as model multimeric lectins, we have shown that α-mannose and α-manno-α-1,2-biose (abbreviated as Man and DiMan, respectively) coated GNPs not only can provide sensitive measurement of MLGI affinities but also reveal critical structural information (e.g., binding site orientation and mode) which are important for MLGI targeting. In this study, we produced mannuronic acid (ManA) coated GNPs (GNP-ManA) of two different sizes to probe the effect of glycan modification on their MLGI affinity and antiviral property. Using our recently developed GNP fluorescence quenching assay, we find that GNP-ManA binds effectively to both DC-SIGN/R and increasing the size of GNP significantly enhances their MLGI affinity. Consistent with this, increasing the GNP size also significantly enhances their ability to block DC-SIGN/R-augmented virus entry into host cells. Particularly, ManA coated 13 nm GNP potently block Ebola virus glycoprotein-driven entry into DC-SIGN/R-expressing cells with sub-nM levels of EC₅₀. Our findings suggest that GNP-ManA probes can act as a useful tool to quantify the characteristics of MLGIs, where increasing the GNP scaffold size substantially enhances their MLGI affinity and antiviral potency. Full article

Monkeypox virus (MPXV) has caused 148,892 confirmed cases and 341 deaths from 137 countries worldwide, as reported by the World Health Organization (WHO), highlighting the urgent need for effective vaccines to prevent the spread of MPXV. Traditional vaccine development is low-throughput, expensive, time consuming, and susceptible to reversion to virulence. Alternatively, a reverse vaccinology approach offers a rapid, efficient, and safer alternative for MPXV vaccine design. Here, MPXV proteins associated with viral infection were analyzed for immunogenic epitopes to design multi-epitope vaccines based on B-cell, CD4+, and CD8+ epitopes. Epitopes were selected based on allergenicity, antigenicity, and toxicity parameters. The prioritized epitopes were then combined via peptide linkers and N-terminally fused to various protein adjuvants, including PADRE, beta-defensin 3, 50S ribosomal protein L7/12, RS-09, and the cholera toxin B subunit (CTB). All vaccine constructs were computationally validated for physicochemical properties, antigenicity, allergenicity, safety, solubility, and structural stability. The three-dimensional structure of the selected construct was also predicted. Moreover, molecular docking and molecular dynamics (MD) simulations between the vaccine and the TLR-4 immune receptor demonstrated a strong and stable interaction. The vaccine construct was codon-optimized for high expression in the E. coli and was finally cloned in silico into the pET21a (+) vector. Collectively, these results could represent innovative tools for vaccine formulation against MPXV and be transformative for other infectious diseases. Full article

Glycyrrhizic acid (GA) and its derivatives have been reported to have potent pharmacological effects against viral infections, including SARS-CoV and SARS-CoV-2. However, their antiviral mechanisms against coronaviruses are not fully understood. In this study, we found that diammonium glycyrrhizinate (DG) can effectively reduce infections of several human coronaviruses, including HCoV-OC43, HCoV-229E, and SARS-CoV-2, as well as newly emerged variants, with EC₅₀ values ranging from 115 to 391 μg/mL being recorded. Time-of-addition and pseudotype virus infection studies indicated that DG treatment dramatically inhibits the process of virus entry into cells. Furthermore, we demonstrated that DG broadly binds to the RBD of human coronaviruses, thereby blocking spike-mediated cellular entry, by using TR-FRET-based receptor-binding domain (RBD)-ACE2 interaction assay, capillary electrophoresis (CE), and surface plasmon resonance (SPR) assay. In support of this notion, studies of molecular docking and amino acid mutation showed that DG may directly bind to a conserved hydrophobic pocket of the RBD of coronaviruses. Importantly, intranasal administration of DG had a significant protective effect against viral infection in a HCoV-OC43 mouse model. Finally, we found that combinations of DG and other coronavirus inhibitors exhibited antiviral synergy. In summary, our studies strongly reveal that DG exerts broad-spectrum antiviral activity against human coronaviruses by interrupting spike-mediated cellular entry, demonstrating the pharmacological feasibility of using DG as a candidate for alternative treatment and prevention of coronavirus infection. Full article

In the current global health environment, the spread of the monkeypox virus (MPXV) and the persistent threat of human immunodeficiency virus (HIV) have become critical public health challenges. Since 2022, MPXV has rapidly disseminated worldwide, and nearly half of MPXV-infected individuals are co-infected with HIV. This complex situation calls for innovative preventive strategies. In this study, an innovative multi-epitope vaccine was designed using bioinformatics and immunoinformatic approaches. Ten HIV proteins and nine MPXV proteins were used to predict potential epitopes. Non-allergenic, highly antigenic, IFN-γ-inducible, and non-toxic epitopes were selected to construct the multi-epitope vaccine. It was found that the designed vaccine construct was highly antigenic, soluble, and had acceptable physicochemical properties. Based on molecular docking and molecular dynamics simulation (MDs) analyses, the vaccine construct demonstrated stable and robust interactions with Toll-like receptors (TLR2, TLR3, and TLR4). Although no actual animal experiments have been conducted to evaluate the vaccine’s effectiveness, immune simulations showed that the vaccine could elicit potent humoral and cell-mediated immune responses. Overall, this study provides a promising vaccine candidate against MPXV and HIV co-infection and emphasizes innovative strategies to interrupt the international transmission of these two viruses. Full article

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the 2019 coronavirus disease pandemic. The virus primarily spreads through person-to-person contact via aerosols and droplets, contributing to high case numbers and related morbidities. SARS-CoV-2 targets the respiratory tract, causing acute respiratory distress syndrome, particularly in immunocompromised individuals such as those with cystic fibrosis (CF). CF is a life-threatening genetic disorder caused by mutations in the CF transmembrane conductance regulator (CFTR) gene, leading to impaired respiratory function and recurrent severe respiratory symptoms. Despite their potential vulnerability, CF patients have shown a lower incidence of severe COVID-19, suggesting protective factors against SARS-CoV-2. Differential expression of the ACE2 receptor, crucial for viral entry, and other host factors, such as TMPRSS2, may play a role in this resistance to SARS-CoV-2. Analyzing the genomics and transcriptomics profiles of CF patients could provide insights into potential resistance mechanisms. The potential resistance mechanisms include blood and extracellular ATP levels, a deleted/dysfunctional CFTR gene, ACE and ACE2 regulation and expression, ACE and ACE2 polymorphism effects, host proteins and SARS-CoV-2 interactions, and SMN1 and ACE/ACE2 interactions. This review discusses the underlying factors and potential resistance mechanisms contributing to CF patients’ responses to SARS-CoV-2 infection. The review provides an opportunity to further investigate future therapy and research through understanding the underlying potential resistance mechanisms exhibited by CF patients against SARS-CoV-2, including ACE and ACE2 polymorphisms. Full article

The diversity of structural types of carrageenans (CRGs)—sulfated polysaccharides of red algae—determines their different biological activities. The different types of CRGs (kappa, lambda, kappa/beta-CRGs) were isolated from the red algae of the Pacific coast. Molecular docking was performed to determine potential interactions of CRGs with the receptor-binding domain (RBD) of SARS-CoV-2 and its cellular receptor—angiotensin—converting enzyme type 2 (ACE2). CRGs interacted with ACE2 and RBD via hydrogen bonding and ionic interactions. The strongest binding affinity of CRGs and ACE2 was observed for kappa-CRG. Molecular docking was confirmed by results studying the effects of CRGs against SARS-CoV-2 in vitro. The ability of CRGs, as well as the complex CRG with sea urchin echinochrome (Ech), to inhibit SARS-CoV-2 replication in Vero E6 cells was studied using cytopathic effect (CPE) inhibition and RT-PCR assays. The simultaneous treatment of cells with CRGs and the virus revealed that kappa-CRG exhibited the most significant antiviral effect among all the polysaccharides, with a selective index (SI) of 33. The kappa-CRG/Ech complex exhibited the highest virucidal effect on SARS-CoV-2 particles with an SI above 70 (more than two times higher than that of CRG and Ech) and reduced viral RNA levels by 45% (IC = 45%). Our results illustrate that CRGs and kappa-CRG/Ech complex can act as protective agents against SARS-CoV-2. Full article

Background/Objectives: For viral entry into host cells, the spike (S) protein of coronavirus (CoV) uses its S1 domain to bind to the host receptor and S2 domain to mediate the fusion between virion and cellular membranes. The S1 domain acquired multiple mutations as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) evolved to give rise to Variant of Concerns (VOCs) but the S2 domain has limited changes. In particular, the stem helix in S2 did not change significantly and it is fairly well-conserved across multiple beta-CoVs. In this study, we generated a murine mAb 7B2 binding to the stem helix of SARS-CoV-2. Methods: MAb 7B2 was isolated from immunized mouse and its neutralization activity was evaluated using microneutralization, plaque reduction and cell–cell fusion assays. Bio-layer interferometry was used to measure binding affinity and AlphaFold3 was used to model the antibody–antigen interface. Results: MAb 7B2 has lower virus neutralizing and membrane block activities when compared to a previously reported stem helix-binding human mAb S2P6. Alanine scanning and AlphaFold3 modeling reveals that residues K1149 and D1153 in S form a network of polar interactions with the heavy chain of 7B2. Conversely, S2P6 binding to S is not affected by alanine substitution at K1149 and D1153 as indicated by the high ipTM scores in the predicted S2P6-stem helix structure. Conclusions: Our detailed characterization of the mechanism of inhibition of 7B2 reveals its distinctive binding model from S2P6 and yields insights on multiple neutralizing and highly conserved epitopes in the S2 domain which could be key components for pan-CoV vaccine development. Full article

Infectious laryngotracheitis (ILT) is a severe upper respiratory disease highly contagious in chickens that causes a huge economic impact on the poultry industry all over the world. The current study aimed to design a multi-epitope-based vaccine candidate using envelope glycoprotein B and glycoprotein D of the ILT virus using an immune informatics approach. The glycoproteins B and D are crucial for attachment as well as entry of ILT virus inside the cell, which makes them a potential option for designing vaccine candidates. The prediction of epitopes, viz. helper T lymphocyte, cytotoxic T lymphocyte and interferon-gamma producing epitopes, was performed and high-scoring predicted epitopes were joined in an organized manner using suitable linkers to design the final vaccine candidate. The avian beta-defensin 1 was included as an adjuvant in the amino-terminal of the vaccine design that possesses antimicrobial activity and histidine residues at the carboxy-terminal for the purpose of purification. The final vaccine candidate was evaluated for its physicochemical characteristics, solubility, antigenicity, stability, and allergenicity and validated for its modeling. Molecular docking, binding affinity, and interacting residues between the vaccine candidate and immune receptors, viz. TLR 3, MHC Class I and Class II were assessed. Further, to assess the immune response profile generated by the final vaccine design, an insilico immune simulation study was also performed. The findings of this study revealed that the final vaccine candidate was antigenic, nonallergenic, stable, interacted with immune receptors, and able to produce antibodies as well as cellular immune responses against ILTV infection. Full article

Feline parvovirus (FPV) causes feline panleukopenia, a highly contagious disease in cats, marked by severe leukopenia, biphasic fever, diarrhea, vomiting, and hemorrhagic enteritis. Recently, FPV infection in giant pandas has increased, causing diarrhea and ultimately fatal outcomes, thereby threatening their survival and reproduction. Here, we investigated the transmission of FPV in giant pandas and its interaction with cellular receptors using an FPV strain (pFPV-sc) isolated from giant panda feces. Recombinant feline transferrin receptor 1 (fTfR1) and the giant panda ortholog (gpTfR1) were expressed in non-susceptible HEK293T and HeLa cells, while viral infection levels were measured to determine the effect of gpTfR1 on pFPV-sc replication. The findings indicated that gpTfR1 overexpression in non-susceptible cells significantly enhanced pFPV-sc replication, particularly influencing the viral attachment and internalization stages. Our data further revealed early-stage colocalization between gpTfR1 expression and virus infection, suggesting that gpTfR1 facilitates early viral infection and replication. Taken together, our study provides the first evidence on the mechanism of FPV cross-species infection in giant pandas and elucidates the interaction between gpTfR1 and FPV, which establishes a theoretical basis for the development of preventive and therapeutic strategies, thereby safeguarding the health and survival of giant panda populations from FPV. Full article

Norovirus is a leading cause of viral gastroenteritis worldwide and has been studied extensively from the perspective of life and biomedical sciences. However, no biothermodynamic analysis of Norovirus has been reported in the literature. Such an analysis would provide insights into the role of energetic constraints in the interactions between Norovirus and its host cells and other viruses. In this research, Norovirus was characterized from the aspect of chemistry and chemical thermodynamics, with the determination of its molecular formula, empirical formula, molar mass and thermodynamic properties (enthalpy, entropy, Gibbs energy) of formation. Based on these properties, biosynthesis reactions were formulated that show how Norovirus particles are synthetized inside host cells, and the thermodynamic properties of biosynthesis were determined. Moreover, the thermodynamic properties of the binding of Norovirus to its host cell receptor were determined. These were then used to develop a model of virus–host interactions at the cell membrane (antigen-receptor binding) and inside the cytoplasm (virus multiplication), with the phenomenological equations of nonequilibrium thermodynamics. Based on the model, an analysis of the virus–virus competition between Norovirus and Rotavirus was conducted. Full article

Background/Objectives: Enterovirus-D68 (EV-D68) and rhinoviruses are major contributors to respiratory illnesses in children, presenting a spectrum of clinical manifestations ranging from asymptomatic cases to severe lower respiratory tract infections. No specific antiviral treatments are currently approved for these viruses. Method: We conducted a comprehensive literature review of antiviral agents investigated for EV-D68 and rhinovirus infections. Results: Several antiviral candidates are under investigation, each targeting distinct stages of the viral replicative cycle. Capsid-binding agents and monoclonal antibodies prevent viral attachment by blocking receptor-virus interactions. Inhibitors of viral replication proteins disrupt polyprotein processing and replication organelle biogenesis by targeting non-structural viral proteins. Host factor inhibitors impair viral attachment, replication organelle formation, or RNA replication by interfering with critical host pathways. Conclusions: While no specific antivirals are yet approved for EV-D68 and rhinovirus infections, emerging therapeutic candidates offer potential avenues for treatment. Continued preclinical and clinical investigation will be essential to validate these approaches and expand the available options for affected patients. Full article

The influenza A viruses (IAV) are the principal pathogens for annual (seasonal) influenza, which cause world-wide outbreaks in poultry and pose a persistent threat to public health. The Hemagglutinin protein (HA) of IAV promotes virus infection by binding the host membrane receptor and mediating virus–host membrane fusion. Immunoprecipitation–mass spectrometry (IP-MS) provides global insights into IAV HA–host protein interactions. However, various experimental conditions might affect the identification of interactions. Here, we performed a serial IP-MS to compare interactors of IAV HA in accidental host human, chicken and reservoir host duck cells. We found that the positive ratio of interactors identified by the IP-MS was improved when the transfected HA plasmid had a similar expression level to HA proteins found in IAV virus infection. Comparing interactors in human, chicken and duck cells, we found that HA–interacting host factors might play a role in the susceptibility of accidental hosts (human and chicken) to IAV infection compared to reservoir hosts (duck). We then focused on the function of two heat shock proteins (HSPA5 and HSPA8), which interacted with IAV HA proteins in all three species (human, chicken and duck). We found that both HSPA5 and HSPA8 promoted the IAV replication by enhancing the viral attachment and internalization. These findings extend our knowledge about the mechanisms of IAV entry to host cells and provide target genes to create chickens resistant to avian influenza. Full article

Avian leukosis virus (ALV), the prototypical alpharetrovirus, causes tumorigenesis, immunosuppression, and wasting disease in poultry. The ALV genus is classified into ten subgroups, which differ in their host range, cell tropism, and receptor usage. The subgroups A, B, K, and J cause significant economic losses worldwide. The most recently discovered subgroup, ALV-K, which is now widespread in China, has been shown to use the tva cell receptor and share it with ALV-A. However, the specific amino acid residues crucial for ALV-K host cell entry remain unknown. Using precise tva expression and chimeric tva receptors, we further elucidated the significance of the cysteine-rich domain in mediating interactions with both ALV-A and ALV-K. Through a comprehensive analysis of mutated tva receptor variants, we pinpointed tryptophan at position 33 (W33) as a pivotal amino acid residue essential for ALV-K virus binding and entry. Of note is the finding that the substitution of W33 induced resistance to ALV-K while preserving sensitivity to ALV-A. This study not only represents an advance in the understanding of the specificity of the tva receptor for ALV-K, but also offers a biotechnological strategy for the prevention of ALV-K infections in poultry. Full article

Mpox (MPX), caused by the Monkeypox virus (MPXV), is a zoonotic orthopoxvirus infection with increasing global relevance due to sustained human-to-human transmission. While primarily known for cutaneous and systemic involvement, emerging evidence suggests that MPX may also disrupt endocrine function. This narrative review aims to synthesize current clinical, experimental, and epidemiological findings on MPX-related endocrine complications. We explore the potential impact of MPXV on the thyroid, adrenal glands, and gonads, and discuss the underlying mechanisms, clinical manifestations, and implications for patient management. MPX has been implicated in viral-induced subacute thyroiditis, with cases exhibiting thyrotoxicosis followed by hypothyroidism, likely mediated by direct viral infiltration or immune dysregulation. Additionally, MPX may contribute to adrenal insufficiency through viral invasion, immune-mediated destruction, or hypothalamic–pituitary–adrenal (HPA) axis dysfunction, exacerbating metabolic and inflammatory complications. MPXV’s persistence in testicular tissue raises concerns about reproductive health, with potential implications for fertility, hormone production, and viral transmission. The virus may also modulate host steroid pathways through interactions with glucocorticoid, androgen, and estrogen receptors, influencing immune responses and disease severity. Given these findings, clinicians should maintain vigilance for endocrine dysfunction in MPX patients, particularly in immunocompromised individuals. The role of steroid therapy in MPX remains complex, requiring careful balancing of its anti-inflammatory benefits against potential risks of viral persistence and immune suppression. Further research is essential to clarify MPX’s endocrine impact and optimize management strategies. Full article

Mesenchymal stromal cells (MSCs) represent a promising therapeutic approach in viral infection management. However, their interaction with viruses remains poorly understood. MSCs can support antiviral immune responses and act as viral reservoirs, potentially compromising their therapeutic potential. Innate immune system recognition of viral pathogens involves pattern recognition receptors (PRRs), including RIG-I-like receptors (RLRs), which activate mitochondrial antiviral signaling protein (MAVS). MAVS triggers antiviral pathways like IRF3 and NF-κB, leading to interferon (IFN) production and pro-inflammatory responses. This study explores the antiviral response in umbilical cord-derived MSCs (UC-MSCs) through targeted stimulation with influenza A virus-derived 5′triphosphate-RNA (3p-hpRNA), a RIG-I agonist. By investigating MAVS activation, we provide mechanistic insights into the immune response at the molecular level. Our findings reveal that 3p-hpRNA stimulation triggers immune activation of the IRF3 and NF-κB pathways through MAVS. Subsequently, this leads to the induction of type I and III IFNs, IFN-stimulated genes (ISGs), and pro-inflammatory cytokines. Critically, this immune activation occurs without compromising mitochondrial integrity. UC-MSCs retain their capacity for mitochondrial transfer to recipient cells. These results highlight the adaptability of UC-MSCs, offering a nuanced understanding of immune responses balancing activation with metabolic integrity. Finally, our research provides mechanistic evidence for MSC-based interventions against viral infections. Full article