Search Results (693)

Vaccination is the most effective method to counteract infectious diseases in farmed fish. It secures aquaculture production and safeguards the wild stock and aquatic ecosystem from catastrophic contagious diseases. In vaccine development, recombinant subunit vaccines are favorable candidates since they can be economically produced in large quantities without growing many pathogens, as in inactivated or attenuated vaccine production. However, recombinant subunit vaccines are often weak or deficient in immunogenicity, resulting in inadequate defenses against infections. Technologies that can increase the immunogenicity of recombinant subunit vaccines are in desperate need. Enhanced green fluorescence protein (EGFP) has a low antigenicity and is susceptible to folding changes and losing fluorescence after fusing with other proteins. Using these valuable features of EGFP, we comprehend two amphipathic alpha-helical peptides, AH1 and AH3, derived from Hepatitis C virus and Influenza A virus, respectively, that can induce high immune responses of their fused EGFP in fish without affecting their folding. AH3-EGFP has the most elevated cell binding, significantly 62% and 36% higher than EGFP and AH1-EGFP, respectively. Immunizations with AH1-EGFP or AH3-EGFP significantly induced higher anti-EGFP antibody levels 300–500-fold higher than EGFP immunization after the boost injection in rainbow trout. Our results suggest that AH1 and AH3 effectively increase the immunogenicity of EGFP without influencing its structure. Further validation of their value in other recombinant proteins is necessary to demonstrate their broader utility in enhancing the immunogenicity of subunit vaccines. We also suggest that EGFP and its variants are promising candidates for initially screening proper immunogenicity-enhancing peptides or proteins to advance recombinant subunit vaccine development. Full article

Dengue, Zika, yellow fever, chikungunya, and Mayaro arboviruses represent an increasing threat to public health because of the serious infections they cause annually in many countries. Serological diagnosis of these viruses is challenging, making the development of new diagnostic strategies imperative. In this study, we investigated the effectiveness of gold nanorods (GNRs) functionalized with specific anti-dengue and anti-orthoflavivirus antibodies in detecting viral particles. GNRs were created with a length-to-width ratio of up to 5.5, a size of 71.4 ± 6.5 nm, and a light absorption peak at 927 nm, and they were treated with 4 mM polyethyleneimine. These GNRs were attached to a small amount of monoclonal antibodies that target flaviviruses, and the viral particles were detected by measuring the localized surface plasmon resonance using an UV-Vis/NIR spectrometer. The tests found Orthoflavivirus dengue and Orthoflavivirus zikaense in diluted human serum and ground-up mosquitoes, with the lowest detectable amount being 100 PFU/mL. The GNRs described in this study can be used to enhance flavivirus diagnostic tests or to develop new, faster, and more accurate diagnostic techniques. Additionally, the functionalized GNRs presented here are promising for supporting virological surveillance studies in mosquitoes. Our findings highlight a fast and highly sensitive method for detecting Orthoflavivirus in both human and mosquito samples, with a detection limit as low as 100 PFU/mL. Full article

Viral oncolysis is considered a promising cancer treatment method because of its good tolerability and durable anti-tumor effects. Compared with other oncolytic viruses, Newcastle disease virus (NDV) has some distinct advantages. As an RNA virus, NDV does not recombine with the host genome, making it safer compared with DNA viruses and retroviruses; NDV can induce syncytium formation, allowing the virus to spread among cells without exposure to host neutralizing antibodies; and its genome adheres to the hexamer genetic code rule (genome length as a multiple of six nucleotides), ensuring accurate replication, low recombination rates, and high genetic stability. Although wild-type NDV has a killing effect on various tumor cells, its oncolytic effect and working mechanism are diverse, increasing the complexity of generating engineered oncolytic viruses with NDV. This study aims to employ whole-genome CRISPR-Cas9 knockout screening and RNA sequencing to identify putative key regulatory factors involved in the interaction between NDV and human colon cancer HCT116 cells and map their global interaction networks. The results suggests that NDV infection disrupts cellular homeostasis, thereby exerting oncolytic effects by inhibiting cell metabolism and proliferation. Meanwhile, the antiviral immune response triggered by NDV infection, along with the activation of anti-apoptotic signaling pathways, may be responsible for the limited oncolytic efficacy of NDV against HCT116 cells. These findings not only enhance our understanding of the oncolytic mechanism of NDV against colonic carcinoma but also provide potential strategies and targets for the development of NDV-based engineered oncolytic viruses. Full article

Background: Fowl typhoid (FT), a septicemic infection caused by Salmonella Gallinarum (SG), and H9N2 avian influenza are two economically important diseases that significantly affect the global poultry industry. Methods: We exploited the live attenuated Salmonella Gallinarum (SG) mutant JOL3062 (SG: ∆lon ∆pagL ∆asd) as a delivery system for H9N2 antigens to induce an immunoprotective response against both H9N2 and FT. To enhance immune protection against H9N2, a prokaryotic and eukaryotic dual expression plasmid, pJHL270, was employed. The hemagglutinin (HA) consensus sequence from South Korean avian influenza A virus (AIV) was cloned under the Ptrc promoter for prokaryotic expression, and the B cell epitope of neuraminidase (NA) linked with matrix protein 2 (M2e) was placed for eukaryotic expression. In vitro and in vivo expressions of the H9N2 antigens were validated by qRT-PCR and Western blot, respectively. Results: Oral immunization with JOL3121 induced a significant increase in SG and H9N2-specific serum IgY and cloacal swab IgA antibodies, confirming humoral and mucosal immune responses. Furthermore, FACS analysis showed increased CD4+ and CD8+ T cell populations. On day 28 post-immunization, there was a substantial rise in the hemagglutination inhibition titer in the immunized birds, demonstrating neutralization capabilities of immunization. Both IFN-γ and IL-4 demonstrated a significant increase, indicating a balance of Th1 and Th2 responses. Intranasal challenge with the H9N2 Y280 strain resulted in minimal to no clinical signs with significantly lower lung viral titer in the JOL3121 group. Upon SG wildtype challenge, the immunized birds in the JOL3121 group yielded 20% mortality, while 80% mortality was recorded in the PBS control group. Additionally, bacterial load in the spleen and liver was significantly lower in the immunized birds. Conclusions: The current vaccine model, designed with a host-specific pathogen, SG, delivers a robust immune boost that could enhance dual protection against FT and H9N2 infection, both being significant diseases in poultry, as well as ensure public health. Full article

Background/Objectives: SARS-CoV-2 vaccine candidates comprising the receptor binding domain (RBD) of the spike protein have been shown to confer protection against infection. Previous research evaluating vaccine candidates with SARS-CoV-2 RBD fused to ferritin (RBD-ferritin) and other scaffolds suggested that multimeric assemblies of RBD can enhance antigen presentation to improve the potency and breadth of immune responses. Though RBDs directly fused to a self-assembling scaffold can be delivered as messenger RNA (mRNA) formulated with lipid nanoparticles (LNPs), reports of SARS-CoV-2 vaccine candidates that combine these approaches remain scarce. Methods: Here, we designed RBD fused to AP205 or TIP60 self-assembling nanoparticles following a search of available structures focused on several scaffold properties. RBD-AP205 and RBD-TIP60 were tested for antigenicity following transfection and for immunogenicity and neutralization potency when delivered as mRNA in mice, with RBD-ferritin as a direct comparator. Results: All scaffolded RBD constructs were readily secreted to transfection supernatant and showed antigenicity in ELISA, though clear heterogeneity in assembly was observed. RBD-AP205 and RBD-TIP60 also exhibited robust antibody binding and neutralization titers in mice that were comparable to those elicited by RBD-ferritin or a full-length membrane-bound spike. Conclusions: These data suggest that AP205 and TIP60 can present RBD as effectively as ferritin and induce similar immune responses. By describing additional scaffolds for multimeric display that accommodate mRNA delivery platforms, this work can provide new tools for future vaccine design efforts. Full article

Human leukocyte extract (HLE), a non-immunogenic dialyzable leukocyte preparation (<10 kDa), may serve as a safe adjuvant in immunotherapy. We investigated the effects of albendazole (ABZ), HLE, and their combination in Mesocestoides vogae infected mice, focusing on lymphoid cells in the peritoneal cavity, the site of larval proliferation and parasite-induced immunosuppression. Peritoneal lymphoid cells were analysed by flow cytometry and qPCR. Cells proliferative responses to ConA, LPS, and parasite excretory/secretory (E/S) antigens, cytokine production (ELISA), IgM and IgG isotypes in exudates and parasite antigen recognition (Western blot) were assessed. Efficacy was measured by larval burden and 14-3-3 gene expression in larvae. HLE combined with ABZ enhanced larval clearance and suppressed 14-3-3 gene expression in larvae. HLE and combination therapy increased CD3⁺ T cell frequencies, especially CD3^+high, reduced regulatory CD3+/IL-10 Tregs and expression of Foxp3⁺. All treatments diminished CD19⁺/IL-10⁺ Bregs, correlating with lower CD9 and Atf3 mRNA levels compared to infected mice. Transcription factors T-bet expression was strongly upregulated, while GATA3 was moderately elevated. IFN-γ production and T/B cell proliferation were restored after HLE and combination therapy, partially, even in the presence of E/S antigens. IgM and total IgG levels against parasite antigens declined, while Th1-associated IgG2a increased in ABZ+HLE and HLE-treated groups. Albendazole failed to reverse the immunosuppressive Treg-type immunity but was more effective in reducing Breg populations and their functions. HLE enhanced ABZ efficacy by restoring Th1 responsiveness, reducing Treg/Breg activity, and modulating antibody profiles. It represents a promising immunomodulatory adjuvant in the treatment of the infections associated with Th2/Treg-driven immunosuppression. Full article

The 2016 Zika virus (ZIKV) epidemic has largely subsided, but a key question remains. How did ZIKV evolve to become a virulent human pathogen compared to the virus of its original discovery? What specific virologic and pathologic changes contributed to increased pathogenicity in humans? Phylogenetic studies have identified two genetically distinct ZIKV, the African and Asian lineages, which differ in their pathogenicity. Previous studies including ours suggest that the envelope (E) protein plays a key role in viral entry, immune activation, and neuropathogenesis. This study aimed to further elucidate virologic and pathogenic differences between these lineages by assessing their ability to bind and replicate in host cells, induce apoptotic cell death, trigger inflammatory responses, and influence human neural progenitor cell (hNPC)-derived neurosphere formation. We compared a historic African ZIKV strain (MR766) with an epidemic Brazilian strain (BR15) and evaluated the effects of the E protein inhibitor quercetin-3-β-O-D-glucoside (Q3G) and an E protein-neutralizing antibody (AbII). Our results revealed distinct virologic properties and that MR766 exhibited stronger inhibition of neurosphere formation due to enhanced viral binding to neuronal SH-SY5Y cells, while BR15 infection triggered a heightened pro-inflammatory cytokine response with reduced viral binding. Chimeric virus studies suggested that the E protein likely influences viral binding, replication efficiency, immune activation, and neuropathogenesis. Notably, Q3G exhibited antiviral activities against both MR766 and BR15, whereas AbII preferentially inhibited MR766. These findings highlight the virological differences between ancestral and epidemic viral strains, as well as the critical role of E protein in viral permissiveness, immune response, and neuropathogenesis, providing insights for developing targeted antiviral strategies. Full article

Toxoplasma gondii, a parasitic protozoan, causes zoonotic infections with severe health impacts in humans and warm-blooded animals, underscoring the urgent need for effective vaccines to control these infections. In this study, a DNA vaccine encoding TgROP5, TgROP18, TgGRA7, TgGRA15, and TgMIC6 was formulated using the eukaryotic expression vector pVAX I. IL-24 was delivered as a molecular adjuvant using plasmid pVAX-IL-24. BALB/c, C57BL/6, and Kunming mouse strains received the DNA immunization, after which antibody levels, cytokine production, and lymphocyte surface markers were analyzed to assess immune responses. Additionally, survival rates and brain cyst counts were measured 1 to 2 months post-vaccination in experimental models of toxoplasmosis. As a result, compared to controls, the DNA vaccine cocktail significantly increased serum IgG levels, Th1 cytokine production, and proportions of CD4+/CD8+ T cells, leading to extended survival and reduced brain cyst counts post-challenge with T. gondii ME49. Furthermore, the five-gene DNA vaccine cocktail conferred greater protection compared to single-gene immunizations. Co-administration of IL-24 significantly enhanced the immune efficacy of the multi-gene DNA vaccination. Our findings suggest that IL-24 is an effective molecular adjuvant, enhancing the protective immunity of DNA vaccines against T. gondii, supporting its potential role in vaccine strategies targeting other apicomplexan parasites. Full article

Co-infections of dengue serotypes and dengue with other flaviviruses pose substantial hurdles in disease diagnosis, treatment options, and disease management. The overlapping geographic distributions and mosquito vectors significantly enhance the probability of co-infections. Co-infections may result in more severe disease outcomes due to elevated viral loads, modulation of the immune response, and antibody enhancement. Cross-reactivity in serological assays and the likeness of clinical presentations add to the ongoing challenges in disease diagnosis. Molecular diagnostics such as reverse transcription polymerase chain reaction (RT-PCR) and next-generation sequencing (NGS) are, therefore, employed for more specific disease diagnosis although requiring substantial resources. Despite the advancements, specific anti-flaviviral therapy is still limited, hence the urgency for further investigative research into various therapeutic approaches, including peptide inhibitors, host-targeted therapies, and RNA-based interventions. This review discusses the epidemiology, clinical ramifications, and diagnostic obstacles associated with flavivirus co-infections whilst assessing prospective strategies for better disease prevention, treatment, and management. Addressing these critical gaps is essential for disease mitigation whilst improving patient management especially in regions where co-circulation of flaviviruses is common and their diseases are highly endemic. Full article

Background: SARS-CoV-2 booster vaccination remains essential to prevent severe COVID-19, particularly in vulnerable populations such as older adults. This study evaluated the durability and dynamics of immune responses following booster vaccination(s) in >65-year-old individuals and examined their association with protection against new infections. Methods: Immune responses were evaluated at 3, 9, and 15 months post-booster, measuring SARS-CoV-2-specific IgG antibodies against spike [IgG(S)] and nucleocapsid [IgG(N)] proteins, neutralizing activity against the Omicron BA.2 variant, and cellular immunity. A subset of participants was tested before booster administration. Regression analyses examined the influence of clinical and immunological factors—including a bivalent fourth dose—on infection risk over time. Results: Booster vaccination significantly enhanced IgG(S) and neutralizing capacity, peaking at 3 months. Although a decline was observed by 9 months, responses remained above baseline. Individuals with prior SARS-CoV-2 infection exhibited higher IgG(S) levels and neutralizing titers, and significantly lower reinfection rates (15%), compared to uninfected individuals. A fourth vaccine dose further increased IgG(S) levels. While neutralizing capacity was not consistently enhanced by the fourth dose, recipients experienced a lower rate of new infections. Immune trajectory analyses revealed that breakthrough infections elicited strong humoral responses comparable to those seen in previously infected individuals, highlighting the role of hybrid immunity. Conclusions: In older adults, booster vaccination induces durable immune responses, with hybrid immunity offering enhanced protection. A fourth dose boosts antibody levels and reduces infection risk, supporting its use in this high-risk group. Continued monitoring is needed to determine the long-term effectiveness of boosters, particularly against emerging variants. Full article

The feline calicivirus, herpesvirus, and panleukopenia viruses are major infections that cause serious diseases in cats; however, current trivalent vaccines have limitations in immune efficacy and their duration of protection. This study assesses the immune-enhancing effects of novel adjuvants (feline IL-15, IL-23, and metabolic modulators) on vaccine responses. Forty mice were randomly assigned to four groups: Group A (composite adjuvants), Group B (metabolic regulatory molecules and Mn adjuvant), Group C1 (Mn adjuvant), and Group C2 (a blank commercial vaccine). The results showed that Group A had significantly higher neutralizing antibody titers against calicivirus post-booster immunization, while both Groups A and B exhibited enhanced antibody responses against the herpesvirus and panleukopenia viruses. Notably, Group A displayed increased proportions of memory T cells, follicular B cells, and activated B cells. These findings suggest that the combination of feline IL-15, IL-23, and metabolic modulators are safe and effective immunoadjuvants for trivalent feline vaccines to promote immune cell differentiation and antibody production, thus representing a promising strategy to optimize vaccine efficacy. Full article

Respiratory syncytial virus (RSV) is a major human respiratory pathogen, particularly affecting infants, the elderly, and immunocompromised individuals. RSV exists in both spherical and filamentous forms, with the filamentous morphology associated with enhanced infectivity and cell-to-cell spread. Here, we demonstrate that RhoA, a small GTPase involved in cytoskeletal regulation, is essential for filamentous RSV morphogenesis through its role in organizing lipid raft microdomains. Rhosin, a selective RhoA inhibitor developed through structure-guided screening, disrupts GEF–RhoA interactions to block RhoA activation. The pharmacological inhibition of RhoA with Rhosin significantly reduced filamentous virion formation, disrupted RSV fusion (F) protein colocalization with lipid rafts, and diminished cell-to-cell fusion, without affecting overall viral replication. Scanning electron microscopy revealed that Rhosin-treated infected HEp-2 cells exhibited fewer and shorter filamentous projections compared to the extensive filament formation seen in untreated cells. β-galactosidase-based fusion assays confirmed that reduced filamentation corresponded with decreased cell-to-cell fusion. The biophysical separation of RSV spherical and filamentous particles by sucrose gradient velocity sedimentation, coupled with fluorescence and transmission electron microscopy, showed that Rhosin treatment shifted virion morphology toward spherical forms. This suggests that RhoA activity is critical for filamentous virion assembly, which may enhance viral spread. Immunofluorescence microscopy using lipid raft-selective dyes (DiIC₁₆) and fusion protein-specific antibodies revealed the strong co-localization of RSV proteins with lipid rafts. Importantly, the pharmacological inhibition of RhoA with Rhosin disrupted F protein partitioning into raft domains, underscoring the requirement for intact lipid rafts in assembly. These findings highlight a novel role for host RhoA signaling in regulating viral assembly through raft microdomain organization, offering a potential target for host-directed antiviral intervention aimed at altering RSV structural phenotypes and limiting pathogenesis. Full article

Mucosal immunization represents a promising strategy for preventing enteric infections. Rotavirus (RV), a leading gastrointestinal pathogen distinguished by its remarkable stability and segmented double-stranded RNA genome, has been engineered into a versatile oral vaccine vector through advanced reverse genetics systems. The clinical efficacy of live-attenuated RV vaccines highlights their unique capacity to concurrently induce mucosal IgA responses and systemic neutralizing antibodies, positioning them as a multiple action vector for multiple immune protection. In this review, we summarize the RV colonization of the intestine and stimulation of intestinal immunity, as well as recent advancements in RV reverse genetics, and focus on their application in the rational design of a multivalent mucosal vaccine vector targeting enteric pathogens considering the advantages and challenges of RV as a vector. We further propose molecular strategies to overcome genetic instability in recombinant RV vectors, including the codon optimization of heterologous inserts. These insights provide a theoretical foundation for developing next-generation mucosal immunization platforms with enhanced safety, stability, and cross-protective efficacy. Full article

Respiratory syncytial virus (RSV) is a major etiological agent of lower respiratory tract infections, particularly among infants and the elderly. Activation of B cells in the mucosa and the production of specific neutralizing antibodies are essential for protective immunity against pulmonary infection. B-cell activating factor (BAFF) is a critical survival factor for B cells and has been associated with antiviral responses; however, its regulation during RSV infection remains poorly understood. This study examined BAFF regulation in BEAS-2B cells exposed to RSV or IFN-β. The treatments resulted in a progressive increase in gene expression over time, accompanied by higher protein levels. BAFF mRNA peaked at 12 h post-infection and declined by 48 h, coinciding with the release of soluble BAFF protein into the culture supernatant. Pre-treatment with anti-IFN-β antibodies prior to RSV infection reduced both BAFF mRNA and protein levels, indicating that IFN-β plays a regulatory role in BAFF production by airway epithelial cells. Western blot analysis revealed membrane-bound BAFF (~31 kDa) in non-infected cells, with elevated expression at 24 h post-infection. By 48 h, this form was cleaved into a soluble ~17 kDa form, which was detected in the supernatant. Immunostaining further demonstrated reduced surface expression of membrane-bound BAFF in RSV-infected cells compared to uninfected controls, suggesting that RSV infection promotes the cleavage and release of BAFF into the extracellular environment. Additionally, the release of BAFF was not affected by furin convertase inhibition or ER–Golgi transport blockade, indicating a potentially novel cleavage mechanism. Co-culturing BAFF produced by BEAS-2B cells with isolated B cells enhanced B cell viability. Overall, these results indicate that RSV infection stimulates BAFF production in airway epithelial cells through a pathway involving IFN-β, potentially contributing to B cell activation and promoting local antibody-mediated immunity. Understanding this mechanism may offer valuable insights for improving mucosal vaccine strategies and enhancing immunity against respiratory pathogens. Full article

Background: Respiratory syncytial virus (RSV) remains a leading cause of lower respiratory tract infections and hospitalizations in infants and young children globally. Recently, RSV prevention has advanced with the introduction of nirsevimab, a long-acting monoclonal antibody, and the RSV preF vaccine for maternal immunization. While these interventions have improved early protection, several limitations hinder their broader impact and long-term effectiveness. Methods: This narrative review synthesizes evidence from clinical trials, observational studies, and regulatory reports to evaluate the main limitations of nirsevimab and maternal RSV vaccination. Literature searches were conducted in major databases, focusing on efficacy, safety, immunogenicity, implementation, and population-specific challenges. Results: Both nirsevimab and maternal vaccination provide strong protection during the first six months of life, but their effectiveness wanes thereafter. This is concerning as nearly half of RSV-related deaths occur in children over six months old. Maternal vaccine efficacy is uncertain in very-preterm infants, and safety concerns persist, including potential associations with preterm birth, Guillain–Barré syndrome, and hypertensive disorders. Real-world data from low-income countries are lacking, limiting generalizability. Additionally, the risk of vaccine-associated enhanced disease (VAED), although unconfirmed, has delayed pediatric vaccine development. Emerging monoclonal antibodies and live-attenuated vaccines are under investigation to extend protection beyond infancy. Conclusions: Despite substantial progress, current RSV prevention strategies leave critical gaps, particularly for older infants and underserved populations. There is a pressing need for next-generation vaccines, enhanced pharmacovigilance, and equitable global implementation to ensure sustained and inclusive RSV protection. Full article