Search Results (428)

Orthoflaviviruses belong to the flavivirus genus, which is part of the Flaviviridae family. Orthoflaviviruses include major clinically relevant arthropod-borne human viruses such as Dengue, Zika, yellow fever, West Nile and tick-borne encephalitis virus. These viruses pose an increasing threat to global health due to the expansion of arthropod habitats, urbanization, and climate change. While vaccines have been developed for certain orthoflaviviruses with varying levels of success, critical challenges remain in achieving broadly deployable vaccines that combine a robust safety profile with durable immunity against many current and emerging orthoflaviviruses. This review provides a snapshot of established and emerging vaccine platforms against orthoflaviviruses, with a particular emphasis on those leveraging the envelope glycoprotein E as the primary antigen. We examine the strengths and disadvantages of these different platforms in eliciting safe, durable, and robust orthoflavivirus immunity, and discuss how specific attributes such as multivalency, authentic epitope presentations, and logistical practicality can enhance their value in preventing orthoflavivirus infection and disease. Full article

Sindbis virus (SINV), a prototype of the Alphavirus genus (family Togaviridae), is a globally distributed arbovirus causing febrile rash and debilitating arthritis in humans. Viral structural proteins—capsid (C), E1, and E2—are fundamental to the virion’s architecture, mediating all stages from assembly to host cell entry and pathogenesis, thus representing critical targets for study. This review consolidates the historical and current understanding of SINV structural biology, tracing progress from early microscopy to recent high-resolution cryo-electron microscopy (cryo-EM) and X-ray crystallography. We detail the virion’s precise T = 4 icosahedral architecture, composed of a nucleocapsid core and an outer glycoprotein shell. Key functional roles tied to protein structure are examined: the capsid’s dual capacity as a serine protease and an RNA-packaging scaffold that interacts with the E2 cytoplasmic tail; the E1 glycoprotein’s function as a class II fusion protein driving membrane fusion; and the E2 glycoprotein’s primary role in receptor binding, which dictates cellular tropism and serves as the main antigenic target. Furthermore, we connect these molecular structures to viral evolution and disease, analyzing how genetic variation among SINV genotypes, particularly in the E2 gene, influences host adaptation, immune evasion, and the clinical expression of arthritogenic and neurovirulent disease. In conclusion, the wealth of structural data on SINV offers a powerful paradigm for understanding alphavirus biology. However, critical gaps persist, including the high-resolution visualization of dynamic conformational states during viral entry and the specific molecular determinants of chronic disease. Addressing these challenges through integrative structural and functional studies is paramount. Such knowledge will be indispensable for the rational design of next-generation antiviral therapies and broadly protective vaccines against the ongoing threat posed by SINV and related pathogenic alphaviruses. Full article

Schmallenberg virus (SBV) is a negative-sense RNA virus transmitted by insect vectors, causing arthrogryposis-hydranencephaly syndrome in newborn ruminants. Since its discovery in Germany and the Netherlands in 2011, SBV has rapidly spread across multiple European countries, resulting in significant economic losses in the livestock industry. With the increasing global animal trade and the expanded range of insect transmission, the risk of SBV introduction into non-endemic regions is also rising. As the gold standard for serological testing, the virus neutralization test (VNT) is crucial for tracking the spread of SBV and evaluating the efficacy of vaccines. However, in non-endemic regions, the lack of local viral strains and the biosafety risks associated with introducing foreign strains pose challenges to the implementation of VNT. In this study, we employed reverse genetics techniques using vesicular stomatitis virus (VSV) to substitute the VSV G protein with the envelope glycoproteins of SBV, thereby successfully generating and rescuing the recombinant virus rVSVΔG-eGFP-SBVGPC. The recombinant virus was then thoroughly characterized in terms of SBV Gc protein expression, viral morphology, and growth kinetics. Importantly, rVSVΔG-eGFP-SBVGPC exhibited SBV-specific cell tropism and was capable of reacting with SBV-positive serum, enabling the measurement of neutralizing antibody titers. The results suggest that this recombinant virus can serve as a feasible alternative for SBV neutralization tests, with promising potential for application in serological screening and vaccine evaluation. Full article

The Akabane virus (AKAV) is a significant member of the Orthobunyavirus genus, with its envelope glycoprotein Gc, focusing on its molecular structural features, immunoregulatory mechanisms, and application value in pathogen diagnosis and vaccine design. As a key structural protein of AKAV, Gc mediates virus adsorption and neutralizing antibody recognition through the N-terminal highly variable region (HVR), while the C-terminal conserved region (CR) dominates the membrane fusion process, and its glycosylation modification has a significant regulatory effect on protein function. In clinical diagnostics, serological assays based on Gc proteins (e.g., ELISA, immunochromatographic test strips) have been standardized; in vaccine development, the neutralizing epitope of Gc proteins has become a core target for subunit vaccine design. Follow-up studies were deeply needed to analyze the structure-function interaction mechanism of Gc proteins to provide theoretical support for the construction of a new type of AKAV prevention and control system. Full article

Ovine herpesvirus 2 (OvHV-2) causes the fatal veterinary disease malignant catarrhal fever (MCF). Fusion is an essential step in the host cell entry of enveloped viruses and is an important target for vaccine development. OvHV-2 cannot be propagated in vitro, so a robust virus-free cell–cell membrane fusion assay is necessary to elucidate its entry mechanism. OvHV-2 cell–cell fusion requires three conserved herpesviral envelope glycoproteins: gB, gH, and gL. OvHV-2 fusion activity is detectable but low. We hypothesize that enhancing the cell surface expression of gB, which is the core herpesviral fusogen, will increase cell–cell fusion. We generated C-terminal truncation mutants of gB and determined their cell surface expression, subcellular distribution, and fusion activity. Two mutants, including one that lacked the entire cytoplasmic tail domain, failed to function in the cell–cell fusion assay, despite wild-type levels of surface expression. This suggests that the OvHV-2 gB cytoplasmic tail is critical for fusion. A gB mutant truncated at amino acid 847 showed increased surface expression and fusion relative to the wild type. This suggests that the robust fusion activity of gB847 is the result of increased surface expression. gB847 may be used in place of wild-type gB in an improved, more robust OvHV-2 fusion assay. Full article

The Chikungunya virus (CHIKV) continues to pose a significant global health challenge due to the absence of effective antiviral treatments and limited vaccine availability. This study employed a comprehensive in silico workflow, incorporating high-throughput virtual screening, binding free-energy calculations, ADMET (absorption, distribution, metabolism, excretion, and toxicity) analysis, and 200 ns molecular dynamics (MD) simulations, to identify new inhibitors targeting the E1–E2 glycoprotein complex, crucial for CHIKV entry and membrane fusion. Four promising candidates were identified from a library of 20,000 compounds, with CID 136801451 showing the most potent binding (docking score: −10.227; ΔG_bind: −51.53 kcal/mol). The top four compounds exhibited favorable ADMET profiles, meeting nearly all criteria. MD simulations confirmed stable binding and strong interactions between CID 136801451 and the E1–E2 complex, evidenced by consistently low RMSD values. These findings highlight CID 136801451 as a promising CHIKV entry inhibitor, warranting further in vitro and in vivo evaluation to advance the development of effective anti-CHIKV therapeutics. Full article

Background/Objectives: Bovine viral diarrhea virus (BVDV) causes significant economic losses in the cattle industry worldwide. The current vaccines have limited efficacy against diverse BVDV genotypes. Currently, multi-antigen target design and nanocarrier display technologies can provide ideas for broad-spectrum and efficient BVDV vaccine design. Methods: Here we developed a trivalent mRNA vaccine encoding the domains I-II of envelope glycoprotein E2 from three BVDV genotypes (3E2), introduced with bovine IgG1 Fc (bFc), STABILON (hStab), and artificial virus-like particle (ARVLP) containing CD80 transmembrane (TM) domain, FcγRII cytoplasmic domain, and WW domain of ITCH. Then, in vitro expression, in vivo immunogenicity and neutralizing antibody analysis were performed to evaluate the vaccines. Results: The in vitro expression results showed that bFc and hStab dramatically enhanced antigen expression and immunogenicity. In addition, the ARVLP further enhanced the secretion and potency of neutralizing antibodies. Finally, the immunogenicity of the bFc_BVDV_3E2_ARVLP_hStab mRNA vaccine was evaluated in mice, guinea pigs, and lactating goats and high levels of neutralizing antibodies against all three BVDV genotypes were detected. Conclusions: Our trivalent design strategy with bFc, hStab, and ARVLP shows highly efficient expression as well as strong immunogenicity and provides a promising approach for next-generation BVDV vaccines with broader and stronger protection. 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

The Baculovirus Expression Vector System (BEVS) is an important protein and complex biologics production platform. The baculovirus GP64 protein is the major envelope glycoprotein that aids in virus entry and is required for cell-to-cell transmission in cell culture. Several studies have developed strategies around gp64 gene disruption in an attempt to minimize baculovirus co-production. Here, we investigate the result of transiently targeting the baculovirus gp64 gene with CRISPR-Cas9 during infection. Because not all genomes are effectively disrupted, we describe a variant calling methodology that allows the detection of the targeted mutations in gp64 even though these mutations are not the dominant sequences. Using a transfection-infection assay (T-I assay), the AcMNPV gp64 gene was targeted at six different locations to evaluate the effects of single and multiple targeting sites, and we demonstrated a reduction in the levels of baculovirus vectors while maintaining or enhancing foreign protein production when protein was driven by a p6.9 promoter. Viral genomes were subsequently isolated from the supernatant and cell pellet fractions, and our sequencing pipeline successfully detected indel mutations within gp64 for most of the single-guide RNA (sgRNA) targets. We also observed that 68.8% of variants found in the virus stock were conserved upon virus propagation in cell culture, thus indicating that they are not detrimental to viral fitness. This work provides a comprehensive assessment of CRISPR-Cas9 genome editing of baculovirus vectors, with potential applications in enhancing the efficiency of the BEVS. Full article

Background and Objectives: Myricetin, a flavonoid compound, was demonstrated to effectively arrest the cell-to-cell fusion and syncytial development triggered by Nipah virus (NiV) fusion (F) and attachment (G) envelope glycoproteins in vitro involving two permissive mammalian cell lines. Methods: Time-of-addition assays were carried out using codon-optimized NiV wild type (WT) F and G plasmids followed by a challenge with the addition of myricetin 1 h and 6 h post-transfection in HEK 293T and Vero cells. Results: Upon evaluating different myricetin concentrations, it was determined that a 100 μM concentration of myricetin effectively inhibited 64–80% of syncytia in HEK and Vero cells. Interpretation & Conclusions: In this study, we concluded that myricetin mitigated the syncytial development in HEK and Vero cell lines. Given the flavonoid attributes of myricetin which is widely present in fruits, vegetables, tea, and wine, it may be regarded as a phytonutrient and a safer antiviral alternative against Nipah virus infections. Due to the BSL-4 nature of the virus, further research involving live virus culture is necessary to confirm myricetin as a potential antiviral compound for the mitigation of pathological effects of NiV infections. Full article

Members of the family Orthoherpesviridae employs two distinct transmission modes: free virion release and cell-to-cell transmission. The latter enables immune evasion through multiple mechanisms, facilitating infections in skin, mucosa, and neural tissues. This review synthesizes current knowledge on human herpesvirus cell-to-cell transmission mechanisms, including syncytium formation, tight junction exploitation, exosomal transfer, and tunneling nanotube utilization. We analyze how these strategies enhance infection efficiency, evade immune surveillance, and augment pathogenicity. Furthermore, we discuss recent intervention strategies targeting cell-to-cell transmission, including the development of monoclonal antibodies, antiviral drugs, and vaccines. These inights provide a theoretical foundation for developing novel approaches against human herpesvirus infections. Full article

Adaptor protein (AP) complexes are critical components of the cellular membrane transport machinery. They mediate cargo selection during endocytosis and intracellular vesicular trafficking. Five AP complexes have been characterized (AP1-5), and together their roles extend to diverse cellular processes including the homeostasis of membranous organelles, membrane protein turnover, and immune responses. Human Immunodeficiency Virus type 1 (HIV-1) and other lentiviruses co-opt these complexes to support immune evasion and the assembly of maximally infectious particles. HIV-1 Nef interacts with AP1 and AP2 to manipulate intracellular trafficking and downregulate immune-related proteins such as CD4 and MHC-I. Vpu also co-opts AP1 and AP2, modulating the innate defense protein BST2 (Tetherin) and facilitating the release of virions from infected cells. The envelope glycoprotein (Env) hijacks AP complexes to reduce its expression at the cell surface and potentially support incorporation into virus particles. Some data suggest that Gag co-opts AP3 to drive assembly at intracellular compartments. In principle, targeting the molecular interfaces between HIV-1 proteins and AP complexes is a promising therapeutic approach. Blocking these interactions should impair HIV-1’s ability to produce infectious particles and evade immune defenses, leading to novel antivirals and facilitating a cure. Full article

Lassa mammarenavirus (LASV), a member of the family Arenaviridae, is a highly pathogenic virus capable of causing severe systemic infections in humans. The primary host reservoir is the Natal multimammate mouse (Mastomys natalensis), with human infections typically occurring through mucosal exposure to virus-containing aerosols from rodent excretions. To better understand the molecular mechanisms underlying LASV replication in the respiratory tract, we utilized differentiated primary human airway epithelial cells (HAECs) grown under air–liquid interface conditions, closely mimicking the bronchial epithelium in vivo. Our findings demonstrate that HAECs are permissive to LASV infection and support productive virus replication. While LASV entry into polarized HAECs occurred through both apical and basolateral surfaces, progeny virus particles were predominantly released from the apical surface, consistent with an intrinsic apical localization of the envelope glycoprotein GP. This suggests that apical virus shedding from infected bronchial epithelia may facilitate LASV transmission via airway secretions. Notably, limited basolateral release at later stages of infection was associated with LASV-induced rearrangement of the actin cytoskeleton, resulting in compromised epithelial barrier integrity. Finally, we demonstrate that LASV-infected HAECs exhibited a pronounced type III interferon response. A detailed understanding of LASV replication and host epithelial responses in the respiratory tract could facilitate the development of targeted future therapeutics. Full article

Background/Objectives: Cytomegalovirus (CMV) infection expands early endosomes (EEs) into tubular extensions that may contribute to the control of virus replication and virion assembly. Sequential recruitment of protein coats and sorting nexins (SNXs) creates membrane zones at the EEs that serve as scaffolds for membrane tubulation and retrieval of cargo proteins, including host cell signaling proteins and viral glycoproteins. This study aims to investigate whether the SNX3-dependent zone of EEs contributes to CMV replication and assembly. Methods: Protein localization was analyzed by confocal imaging and expression by Western blot. The contribution of SNX3 to murine CMV (MCMV) replication, assembly compartment (AC) formation, and virion release was analyzed by siRNA and shRNA depletion. The impact of other downstream SNXs that act in EE tubulation was investigated by combined siRNA knockdowns of SNX1, SNX2, SNX4, SNX17, and SNX27 on cell lines expressing shRNA for SNX3. Results: The SNX3-162 isoform acting at EEs was efficiently knocked down by siRNA and shRNA. The SNX3-dependent EE zone recruited SNX27 and contributed to Rab10-dependent tubulation within the pre-AC. SNX3 was not essential for MCMV replication but contributed to the SNX27-, SNX17- and SNX4-dependent release of virions. Silencing SNX3 further reduced the release of virions after silencing SNX27, SNX4, and SNX17, three SNXs that control recycling to the plasma membrane. Conclusions: SNX3 contributes to the formation of pre-AC and MCMV assembly. It acts sequentially with SNX27, SNX4, and SNX17 along the recycling pathway in the process of the production and release of infection virions, suggesting that multiple membrane sources may contribute to the secondary envelopment of MCMV virions. Full article

Dengue Fever, a widespread mosquito-borne disease caused by the dengue virus (DENV), poses a major health threat in tropical and subtropical regions worldwide, resulting in millions of infections yearly. Severe cases of dengue fever have a mortality rate of around fifteen percent. Currently, there are no antiviral treatments for this disease and the only FDA-approved vaccine has been known to have adverse effects, especially in children. Thus, there is an urgent need for new therapeutics for Dengue fever. The largest issue with developing an antiviral treatment is that DENV has four serotypes that each differ slightly enough to pose problems with one compound inhibiting all four. This study addresses that challenge to some extent by focusing on in silico screening of potential hits targeting the envelope glycoprotein, which is relatively conserved across these four serotypes. Using pharmacophore screening and in silico evaluation of ligands, we identified compounds which could potentially have high affinity to the envelope glycoprotein for two of the four DENV serotypes. These in silico results were validated experimentally using bio-layer interferometry. These findings lay a foundation for in vitro analysis and hit-to-lead studies, advancing the development of antivirals that can inhibit multiple serotypes of the dengue virus. Full article