Search Results (61)

Adeno-associated viral (AAV) vectors have established themselves as a promising platform for genetic material delivery in clinical practice, evidenced by regulatory approval of multiple therapeutics. Despite proven therapeutic efficacy, safety concerns remain a critical limitation requiring systematic analysis. This review analyzes clinical data to identify mechanisms of toxicity, clinical risks, and strategies for their minimization in AAV gene therapy. The study examines dose-dependent toxicity, immune responses, and organ-specific burdens associated with systemic and local administration routes. Analysis reveals a clear correlation between systemic delivery efficacy and dose-dependent toxicity, with principal mechanisms including capsid-directed immune responses, hepatic burden, and complement system activation leading to thrombotic microangiopathy. Key determinants of the safety profile include pre-existing neutralizing antibodies, vector dose, serotype selection, and patient baseline conditions. Contemporary strategies for toxicity minimization are evolving from reactive management toward proactive risk mitigation, including prophylactic immunosuppressive regimens, vector engineering to alter tropism or reduce immunogenicity, and rigorous post-infusion monitoring. Integration of improved vector constructs, rational immunosuppressive regimens, and rigorous post-infusion surveillance has the potential to expand the therapeutic window of AAV-based gene therapy, achieving an optimal balance between efficacy and safety for a broader patient population. Full article

Foot-and-Mouth Disease (FMD) is caused by the FMD virus. Indirect Sandwich Enzyme-Linked Immunosorbent Assay (IS-ELISA) was standardized to characterize the FMD serotype “O” virus. Total protein content in the guinea pig serum (whole serum), ammonium sulfate precipitated guinea pig serum (ASPGPS) protein and ion-exchange-based purified guinea pig serum (IEGPS) protein was measured as 52 µg/mL, 24 µg/mL and 10 µg/mL respectively. The whole serum of guinea pigs and rabbits showed the 1:32 and 1:64 anti-FMD serotype “O” virus neutralizing antibody titers, while the anti-FMD serotype “O” virus neutralizing antibody titer was 1:128 in the IEGPS proteins. IEGPS protein with 1:128 neutralizing antibody titers were used as capture/trapping antibodies in the standardization of the assay. The IEGPS protein 1:1000 diluted with 10 µg/mL of protein content was found to be optimum for capture/trapping antibodies. To cover residual blank spaces, different available blocking buffers were evaluated and Skimmed Milk Solution 5% in Phosphate-Buffered Saline (PBS5%) proved best amongst blocking buffers. Coating of 1:1000 diluted IEGPS at 37 °C for 1 h followed by storage at 4 °C for overnight was best for incubation time. FMD serotype “O” virus 1:100 diluted was optimum in IS-ELISA. Similarly rabbit anti-FMD serotype “O” virus specific immune serum 1:10,000 diluted and goat anti-rabbit IgG horseradish peroxidase conjugate 1:4000 diluted were found to be optimum during the standardization of the assay. Lastly ELISA plates proved to be best amongst the available plates for assay. In each experiment, the plateau region, test background and plate background were recorded. Lastly it became possible for the establishment of an optimized and potentially cost-effective IS-ELISA requiring further diagnostic validation in research and diagnostic laboratories in the country. Full article

Background/Objectives: Glioblastoma remains the most lethal primary brain tumor in adults, and progress in oncolytic virotherapy is limited by the lack of immunocompetent models permissive to human-tropic viruses. Methods: Here, murine CT-2A and GL261 glioma and B16 melanoma cell lines were engineered to express human Coxsackievirus and Adenovirus Receptor (CXADR) fused to tagBFP, generating “humanized” tumors that preserve parental growth characteristics while acquiring high susceptibility to group B Coxsackieviruses (CVBs) and adenovirus serotype 5. Results: CXADR expression in CT-2A, GL261, and B16 cells markedly enhanced binding, internalization, and replication of CVBs in vitro, with the strongest effect observed for LEV14 (attenuated CVB5), which reached up to 10⁵-fold higher viral titers in humanized cells compared with parental cells. Unchanged sensitivity to vesicular stomatitis virus indicated receptor-specific effects. Humanized CT-2A-CXADR-BFP and GL261-CXADR-BFP cells initiated aggressive subcutaneous and intracranial tumors in syngeneic C57BL/6 mice without signs of immune rejection, and histology and MRI confirmed invasive high-grade glioma phenotypes. In intracranial CT-2A-CXADR-BFP tumors, repeated intratumoral LEV14 administration induced extensive tumor necrosis and prolonged survival despite the rapid development of neutralizing antibodies. Systemic intravenous LEV14 dosing produced strong oncolytic activity against subcutaneous CT-2A-CXADR-BFP tumors, as demonstrated by pronounced tumor growth inhibition, long-lasting regression in a subset of animals with gliomas, and improved overall survival. Conclusions: Collectively, these data establish CXADR-humanized models as versatile, immunocompetent platforms for evaluation of CXADR-dependent oncolytic enteroviruses. Full article

Objectives: This randomized, blinded, positive-controlled phase III clinical trial aims to evaluate the safety and immunogenicity of the Sabin strain-based inactivated polio vaccine (sIPV) produced by Biominhai in healthy infants after primary and booster immunization. Methods: A total of 1200 healthy infants, aged 2 months, were randomly assigned to two groups in a 1:1 ratio to receive either one dose of sIPV or the control wIPV at 2, 3, and 4 months of age, followed by a booster dose at 18 months. The safety and immunogenicity of both the primary and the booster immunization were assessed. Results: The incidence of adverse reactions (AEs) was significantly lower in the sIPV group compared to the wIPV group after the primary immunization. Specifically, redness was the most frequently reported AE, occurring in 9% of the sIPV group versus 14% in wIPV (p = 0.01). Diarrhea was also less common in the sIPV group (3%) compared to the wIPV group (8%, p = 0.0004). Moreover, there were no significant differences in incidence, severity, or symptoms of AEs between the groups after the booster immunization. Most AEs were classified as grade 1, and notably, no serious AEs (SAEs) were associated with the trial vaccine. Seroconversion rates for types 1, 2, and 3 poliovirus neutralizing antibodies, in the sIPV group, exceeded 98% at 30 days after primary immunization and remained above 90% at 30 days after booster immunization. Notably, seroconversion rates for all three serotypes following both primary and booster immunizations were non-inferior to those observed in the wIPV group. Additionally, the geometric mean titers (GMTs) of neutralizing antibodies against all types were significantly higher in the sIPV group. Conclusions: The sIPV produced by Biominhai demonstrated comparable safety and immunogenicity to the control vaccine after both primary and booster immunizations. Full article

Background: Pneumococcal diseases remain a global threat due to the serotype-specific limitations of polysaccharide vaccines. This study evaluated a recombinant protein-based pneumococcal vaccine (PBPV) combining three PspA variants (PRX1/Family1Clade2, P3296/Family2/Clade3, P5668/Family2/Clade4) and detoxified pneumolysin (PlyLD). PspA targets conserved surface epitopes to block immune evasion and achieve broad coverage, while PlyLD neutralizes pore-forming toxins and enhances adaptive immunity. Methods: We evaluated the safety and immunogenicity of the PBPV in animal models. Acute toxicity studies were conducted by administering a single intramuscular injection to ICR mice, whereas chronic toxicity and immunogenicity studies were performed in cynomolgus monkeys via repeated intramuscular injections, with an equal number of male and female animals in both groups. Immune responses were assessed using ELISA, multiplexed opsonophagocytic killing assays (MOPAs), and neutralizing antibody assays. Results: Acute toxicity studies in ICR mice showed no signs of abnormal toxicity or irritation at one-dose levels. In the chronic toxicity study, cynomolgus monkeys received repeated intramuscular injections once every 3 weeks for a total of four administrations, at doses of one dose/monkey and five doses/monkey, followed by a 4-week recovery period. No significant systemic toxic reactions were observed, and the safe dose was determined to be five doses/monkey. In the immunogenicity study of monkey serum, both low-dose and high-dose groups demonstrated significant increases in antigen-specific IgG titers against each component; opsonophagocytic killing activity against pneumococcal strains from Clades 2, 3, and 4 from PspA Families 1 and 2; and neutralization antibody titers against pneumolysin post-vaccination. Conclusions: The recombinant protein-based pneumococcal vaccine exhibited a favorable safety profile and potent immunogenicity in animal models, indicating promise for broad protection against pneumococcal disease. These findings support the further development of PBPVs as a viable alternative to conventional polysaccharide-based vaccines. Full article

Severe dengue virus (DENV) infections are associated with circulating non-neutralizing antibodies generated during heterotypic infections. Although antibodies are key mediators of both protection and pathogenesis, the specific dynamics of B cells (Bc) and their antibody responses remain insufficiently characterized due to limited methods of identifying DENV-specific Bc (DENV-Bc) and the absence of animal models resembling the human disease. Here, we developed a spectral flow cytometry assay employing biotinylated virus-like particles (VLPs) to detect DENV-Bc in C57BL/6 mice and children hospitalized with dengue. DENV-1 and DENV-2 VLPs were biotinylated, and the efficiency of biotin incorporation was assessed with an HABA-avidin assay and ELISA. Serotype specificity and optimal binding conditions were confirmed using hybridomas 4G2 (pan-flavivirus) and 3H5-1 (DENV-2 specific). Fluorescent agglutimers were subsequently generated by coupling biotinylated VLPs to streptavidin–fluorochrome complexes. Splenocytes from intraperitoneally DENV-infected mice and peripheral blood mononuclear cells (PBMCs) from naturally infected pediatric patients were stained with these VLPs and Bc-lineage markers. Biotinylated VLPs bound specifically to hybridomas, and this binding was competitively inhibited by unlabeled VLPs. After secondary DENV challenge, VLPs identified DENV-specific class-switched plasmablasts in mice. Circulating DENV-specific plasmablasts were also detected in children, with agglutimers enabling the discrimination of serotype-specific and cross-reactive responses in primary and secondary infections. This VLP-based approach represents a scalable platform to investigate the protective and pathogenic roles of DENV-Bc in infection and vaccination. Full article

Vaccination remains the primary strategy for controlling infectious diseases in farm animals. However, current conventional vaccines demonstrate clinical limitations including suboptimal immunogenicity and frequent booster requirements, which compromise disease management efficacy. This study presents an innovative vaccine platform combining yolk immunoglobulin (IgY) with inactivated antigens as co-immunization components. We developed two formulations targeting economically significant pathogens: avian Fowl Adenovirus Serotype 4 (FAdV-4) and Porcine Epidemic Diarrhea Virus (PEDV). For FAdV-4 vaccine evaluation in specific pathogen-free (SPF) chickens, the IgY-antigen complex demonstrated superior immunogenic properties compared to conventional inactivated vaccines. When administered as a single dose at 14 days of age, the experimental formulation elicited significantly stronger humoral responses as measured by both serum neutralization (SN₅₀) and ELISA. Notably, this vaccination strategy provided 100% protection against lethal FAdV-4 challenge from 0 h to 20 weeks post-vaccination, with complete absence of clinical disease manifestations. In PEDV assessment using mouse models, the IgY-antigen formulation induced significantly higher antibody titers than inactivated antigen alone at all post-immunization timepoints (p < 0.01). Comparative analysis revealed our dual-component platform enhanced both the intensity and rapidity of protective immune responses compared to traditional inactivated vaccines. These findings establish that the IgY-antigen co-immunization strategy represents a promising approach for developing new veterinary vaccines with improved protective efficacy. The platform’s ability to generate robust, rapid-onset immunity while maintaining single-dose effectiveness addresses critical limitations of current vaccine technologies. Full article

Background: The minimized pan-coronavirus (CoV) vaccine-1 developed by our laboratory contained pDNA sequences of feline coronavirus serotype-1 (FCoV1) and SARS-CoV2 (SCoV2) spike B-cell epitopes plus FCoV/SCoV2-conserved, CoV-specific polymerase cytotoxic T-lymphocyte (CTL) epitopes formulated in lipid nanoparticle (LNP). Only FCoV2 infects feline cell lines needed for developing native challenge inoculum that causes feline infectious peritonitis (FIP). Hence, Pilot Study 1 evaluated the therapeutic efficacy and safety of the pan-CoV vaccine-1 in feline immunodeficiency virus (FIV)-infected cats, with or without FCoV1 coinfection. Pilot Study 2 evaluated the cross-protective effect of pan-CoV vaccines in specific-pathogen-free (SPF) cats against intranasal challenge with FIP virus serotype 2 (FIPV2). Methods: In Study 1, we vaccinated two FIV-infected cats (one negative and another positive for FCoV1 coinfection) intramuscularly twice with CTL epitopes-LNP vaccine and later twice with pan-CoV vaccine-1. Controls included two unvaccinated FIV-infected cats with or without FCoV1 coinfection. Study 2 assessed the sequential vaccinations of three pan-CoV vaccines in four SPF cats. The first two vaccinations were with pan-CoV vaccine-2, followed by pan-CoV vaccine-3 (twice), and lastly with pan-CoV vaccine-1 (once). Three SPF controls included two cats immunized with LNP and one lacking any immunization. Pan-CoV vaccine-2 contained pDNAs with modified FCoV1/SCoV2 B-cell epitopes plus CTL epitopes in LNP. Pan-CoV vaccine-3 contained only pDNAs with FCoV1 B-cell epitopes plus CTL epitopes in LNP. Results: Study 1 demonstrated no adverse effect with 25 μg and 50 μg CTL epitopes-LNP vaccine and 50 μg pan-CoV vaccine-1. However, 100 μg pan-CoV vaccine-1 caused fever 24 h later, which was resolved by a single Meloxicam treatment. Both vaccinees developed cross-FCoV2 neutralizing antibodies (XNAbs), immunoblot binding antibodies (bAbs) to FCoV1 receptor-binding domain (RBD), and T-cell responses to FCoV1 RBD, whereas one vaccinee also developed bAbs to SCoV2 RBD. Study 2 demonstrated no adverse effects after each vaccination. Three vaccinees developed low-titer XNAbs and bAbs to FCoV2 spike-2 by the fourth vaccination. Upon challenge, all cats developed FCoV2 NAbs and bAbs to FCoV2 nucleocapsid and RBD. High vaccine-induced T-cell responses to FCoV1 RBD and T-cell mitogen responses declined with an increase in responses to FCoV2 RBD at three weeks post-challenge. Two of the three controls died from FIP, whereas one vaccinee, with the lowest vaccine-induced immunity, died from skin vasculitis lesions and detection of FIPV2 infection by semi-nested RT-snPCR in feces. Conclusions: In Pilot Study 1, the pan-CoV vaccine-LNP dose of 50 μg had no adverse effects, but adverse effects were observed at 100 μg dose. In Pilot Study 2, the FCoV1-based B-cell vaccine(s) induced low levels of XNAbs against FIPV2 and delayed challenge infection against high-dose FIPV2. The high-dose FIPV2 infections in the vaccinated and control cats started to clear, by single housing at 23–26 weeks post-challenge, whereas two cats in Pilot Study 1 cleared natural FCoV1 transmission by 26 weeks post-infection. Full article

Bluetongue virus (BTV) is the causative agent of the significant livestock disease Bluetongue (BT), which causes severe economic losses associated with its considerable impact on the health and trade of ruminants. Background/Objectives: BTV infection and vaccination against the virus typically result in the induction of antibodies with the capacity to neutralize viral infection. Classic neutralization approaches resemble the methodology applied for neutralizing antibodies (NAbs) quantification. To improve long-standing and new-generation methodologies for the quantification of NAbs or evaluation of antivirals, we offer here the development of a new luciferase-based microneutralization approach as a proof-of-concept. Methods: Central to this innovative approach is the recently generated set of replication-competent reporter-expressing recombinant BTV, where the NanoLuc luciferase protein expression serves as a quantifiable readout for viral replication. After evaluating a set of heat-inactivated serum samples with neutralizing activity (measured via SNTs), these were incubated with 100 PFU of NLuc-expressing rBTV of serotype 1, 4 or 8 and Vero cells were infected with the serum–virus mixture. Then, the luminescent signal was measured at 48 h post-infection. Results: Using the proposed NLuc-based assay and the luminescent signal in the supernatant, we could detect neutralizing activity as soon as 48 h post-infection. Importantly, we were able to observe a strong correlation between NAbs titers measured by classic microneutralization assay and by our bioluminescent approach (BTV-1 Spearman r = 0.932901; p-value < 0.0001; BTV-4 Spearman r = 0.8070192; p-value < 0.0001; BTV-8 Spearman r = 0.9983; p-value < 0.0001). In addition, the NLuc-based assay displayed a serotype-specific character potentially equivalent to classic SNT methods. Conclusions: In summary, our reporter-based microneutralization assay provides a rapid and suitable method to quantify BTV-neutralizing antibodies in serum samples of natural hosts after vaccination or infection, with a serotype-specificity equivalent to classic SNT methods. Full article

Background/Objectives: Virus-like particle (VLP) vaccines based on human papillomavirus (HPV) L1 proteins have high efficacy for preventing cervical cancer and other HPV-associated diseases. The production yields of commercial HPV VLPs remain suboptimal. We aimed to improve HPV VLP production efficiency using a hyper-expression vector system for the expression of L1 proteins of four major HPV serotypes—HPV 6, 11, 16, and 18. Methods: HPV L1 proteins were expressed in Trichoplusia ni (Hi5) insect cells via a hyper-expression baculovirus vector system. Following cell lysis using a microfluidizer, VLPs were purified through a two-step chromatographic process. Particle morphology was characterized using transmission electron microscopy and dynamic light scattering. Immunogenicity was evaluated using a murine model; mice received three intramuscular injections of the purified quadrivalent VLPs. The resulting IgG and neutralizing antibody responses were compared with those elicited by the commercial quadrivalent vaccine, Gardasil. Results: The L1 proteins from HPV 6, 11, 16, and 18 were successfully expressed at high levels in Hi5 cells, forming uniformly sized VLPs with hydrodynamic diameters of 50–60 nm. The average production yield of the quadrivalent VLPs exceeded 40 mg/L, an improvement over conventional yields. The candidate VLPs elicited strong HPV-specific IgG and neutralizing antibody responses in mice, comparable to those induced by Gardasil. Conclusions: The hyper-expression baculovirus vector system enables high-yield production of HPV L1 VLPs with desirable structural and immunogenic properties. This approach holds promise for the cost-effective and scalable manufacturing of next-generation HPV VLP vaccines, facilitating broader global access to HPV immunization. Full article

Introduction: Dengue virus (DENV) remains a global health threat, with four distinct serotypes (DENV1-4) that complicate vaccine development due to low-affinity, cross-reactive antibodies that increase the risk of antibody-dependent enhancement (ADE). Objective: To address the challenge of inducing strictly serotype-specific immune responses, this study explored the use of targeting individual lymph nodes (LNs) for the creation of simultaneous but independent immune responses as a targeted approach to reduce cross-reactivity and improve vaccine specificity. Methods: In the initial experiments, targeting individual LN successfully induced specific germinal centers (GCs) for different antigens in distinct LNs, highlighting its potential to enhance immune specificity. This approach was further tested using two virus-like particle (VLP)-based vaccines based on AP205 for DENV1 and DENV4, selected due to their genetic divergence and to probe the potential to minimize cross-reactive immune responses. In this setup, AP205-DV1 and AP205-DV4 were administered in targeted separate LNs, and the specificity of the immune response was compared to subcutaneous administration of a mixture of both vaccines. Results: Our data show that targeting distinct LNs elicited antibodies with significantly higher avidity, which is a critical factor in determining the neutralizing capacity of the immune response. Avidity measurements confirmed that this segregation approach results in a more refined selection of high-affinity B cells. Neutralization experiments demonstrated that targeting distinct LNs with individual vaccines induced a more potent and serotype-specific neutralizing response, compared to the injection of a vaccine mixture. Conclusions: These findings suggest that targeting individual LNs could be a promising method for enhancing both the specificity and potency of immune responses, particularly for flaviviruses. Targeting distinct LNs by direct administration of individual vaccines into distinct watersheds rather than individual lymph nodes will offer the opportunity to facilitate the approach in humans. Full article

Background/Objectives: This study investigated susceptibility factors that may contribute to Post-Polio Syndrome (PPS) in elderly polio survivors. Methods: Serum immunoglobulin (Ig) levels, poliovirus neutralizing antibodies (PV NAb), and vitamin D status were evaluated in 80 PPS patients, 40 family members, and 89 healthy controls. Results: A significant number of PPS patients and their family members showed reduced levels of total IgG and/or IgA, and specific IgG subclasses, indicating a high prevalence of primary humoral immunodeficiencies within these groups. Despite these Ig deficits, PV NAb titers were similar across all groups, indicating high protection against poliovirus, likely due to vaccination campaigns with live virus in Italy and intense exposure to poliovirus, especially in long-term rehabilitation institutions. However, a small group of PPS subjects lacked neutralizing antibodies for specific poliovirus serotypes, suggesting more severe antibody deficiencies. Additionally, PPS subjects had a high prevalence of vitamin D deficiency, which likely increases their risk for osteoporosis/osteopenia and fractures. It is unclear if this deficiency was also present in their infancy, potentially enhancing their susceptibility to poliovirus. Conclusions: Overall, the findings indicate that genetic, immunological, or nutritional factors may increase individual susceptibility to the pathogenic effects of poliovirus. This study—limited to serum antibodies—highlights the complex relationship between immune status and long-term health in aging polio survivors. The results emphasize the need for potent poliovirus drugs and vaccines to help contain possible outbreaks but also—for poliomyelitis survivors—to avoid or mitigate the progression to PPS, the latest phase of this devastating disease. Full article

Background: Rabbit hemorrhagic disease (RHD) is an acute, hemorrhagic and highly lethal infectious disease caused by rabbit hemorrhagic disease virus (RHDV), which causes huge economic losses to the rabbit breeding industry. Moreover, there is limited cross-protection between the two different serotypes of classic RHDV (GI.1) and RHDV2 (GI.2). The shortcomings of traditional inactivated vaccines have led to the development of novel subunit vaccines that can protect against both strains, and the VP60 capsid protein is the ideal antigenic protein. This study focused on developing a bivalent RHDV vaccine that can prevent infection with both GI.1 and GI.2 strains. Methodology: Baculovirus vectors containing classic RHDV and RHDV2 VP60 were co-transfected with linearized baculovirus into sf9 cells and transferred to baculovirus via homologous recombination of the VP60 gene. Infected sf9 cells were lysed, and after purification via Ni-NTA chromatography, VLPs were observed using transmission electron microscopy (TEM). In order to evaluate the immunogenicity of the chimeric RHDV VLP vaccine in rabbits, the RHDV VP60-specific antibody, IL-4, IFN-γ and neutralizing antibody titers were analyzed in serum using ELISA and HI. Results: The recombinant baculovirus system successfully expressed chimeric RHDV VLPs with a diameter of 32–40 nm. After immunization, it could produce specific antibodies, IL-4 and IFN-γ. Following the second immunization, neutralizing antibodies, determined using hemagglutination inhibition (HI) assays, were elicited. Conclusions: These data show that the chimeric RHDV VLP bivalent vaccine for immunized New Zealand rabbits can induce humoral immunity and cellular immunity in vivo, and the immunization effect of the high-dose group is similar to that of the current commercial vaccine. Full article

Foot-and-mouth disease virus (FMDV) continues to pose a significant threat to livestock health and the global agricultural economy, particularly in endemic regions of Asia, Africa, and the Middle East. Current vaccines based on chemically inactivated FMDV present several challenges, including biosafety risks, high production costs, and limited effectiveness against emerging viral variants. To overcome these limitations, we developed virus-like particle (VLP) vaccines targeting FMDV serotypes O, A, and Asia1 using a recombinant Escherichia coli expression system. The resulting VLPs self-assembled into 25–30 nm particles with native-like morphology and antigenic properties, as confirmed by transmission electron microscopy, SDS-PAGE, and Western blot analysis. Immunogenicity was evaluated in mice and pigs using ELISA and virus neutralization tests (VNT), and protective efficacy was assessed through viral challenge studies. All VLPs induced strong serotype-specific antibody responses, with ELISA PI values exceeding 50% and significantly increased VNT titers after booster immunization. In mice, PD₅₀ values were 73.5 (A-type), 32.0 (O-type), and 55.7 (Asia1-type); in pigs, PD₅₀ values reached 10.6 (O-type) and 22.6 (Asia1-type). Notably, the vaccines induced robust immune responses even at lower antigen doses, suggesting the feasibility of dose-sparing formulations. These findings demonstrate that FMDV VLPs produced in E. coli are highly immunogenic and capable of eliciting protective immunity, highlighting their promise as safe, scalable, and cost-effective alternatives to conventional inactivated FMD vaccines. Full article

Background: Botulinum toxin (BoNT), produced by Clostridium botulinum, has transitioned from being a lethal neurotoxin to a versatile therapeutic agent. Its ability to inhibit neurotransmitter release by targeting Soluble N-ethylmaleimide-sensitive factor Attachment Protein Receptor (SNARE) proteins underpins its applications in treating conditions such as spasticity, dystonia, chronic pain, and overactive bladder. The clinical and pharmacological properties of BoNT have been extensively studied, with significant advancements in its therapeutic use, safety profile, and understanding of associated adverse effects. Objective: This comprehensive review aims to consolidate historical developments, molecular mechanisms, clinical applications, and challenges associated with BoNT, with a focus on expanding its therapeutic scope while ensuring safety and efficacy. Method: A narrative approach was used to analyze and synthesize insights from 155 references spanning experimental studies, clinical trials, and reviews. Key topics included BoNT’s historical milestones, mechanisms of action, therapeutic applications, and adverse events. Findings: BoNT demonstrates remarkable efficacy in a wide range of medical and cosmetic applications. In movement disorders such as dystonia and spasticity, it reduces muscle overactivity and improves functional outcomes. In chronic pain management, including migraines and neuropathic pain, BoNT significantly alleviates symptoms by modulating neurotransmitter activity. Cosmetic use for conditions like glabellar lines and hyperhidrosis highlights its precision and safety when administered appropriately. For conditions like strabismus and blepharospasm, BoNT effectively restores muscle control, reducing involuntary contractions. In urological applications, BoNT has proven to be an effective therapy for overactive bladder, offering significant symptom relief in refractory cases. However, concerns about long-distance effects, where the toxin may spread beyond the injection site to affect distant muscles or systems, have been reported in certain high-dose or sensitive populations. These findings emphasize the importance of dose optimization and patient-specific approaches. Adverse effects such as localized pain, hematoma, dysphagia, and systemic effects, particularly in high-risk groups, underscore the need for careful monitoring. The development of immunogenicity, leading to neutralizing antibodies, remains a challenge that impacts long-term therapeutic efficacy. Emerging research on novel serotypes, including BoNT/X, and innovations in delivery mechanisms, offer promising avenues to address current limitations. Advances in optimizing dosing regimens and refining injection techniques have also contributed to minimizing complications and improving outcomes across diverse patient populations. Conclusions: BoNT remains a cornerstone in neurology and cosmetic medicine, with its therapeutic potential still expanding. The balance between efficacy and safety, driven by innovations in formulation and application, underscores the importance of continued research. Future directions should focus on minimizing adverse effects, reducing immunogenicity, and exploring novel indications to further enhance its clinical utility. Full article