Vaccine Delivery Research Articles

Protection of Broiler Chickens Against Necrotic Enteritis by Intrapulmonary Delivery of a Live Clostridium perfringens Vaccine Exploiting the Gut-Lung-Axis Concept.

Clostridium perfringens (CP)-induced necrotic enteritis (NE) is an economically important disease in the broiler chicken industry. The incidence of NE is common in 3-to-6-wk-old broiler chickens, once maternal antibodies start declining. Developing an effective vaccination strategy against NE, preferably delivering a single dose of vaccine at hatch to protect broiler chickens against NE without a booster vaccine, is an enormous challenge. The objective of this study was to induce mucosal immunity in the intestines against NE by intrapulmonary (IPL) delivery of a live CP vaccine at hatch, exploiting the gut-lung-axis (GLA) concept by vaccine delivery following in ovo administration of cytosine-phosphorothioate-guanine oligodeoxynucleotides (CpG-ODN) to induce immune cell maturation in the lungs. Experiments were conducted to explore the dose of CP and immune protection against heterologous CP challenge, and to study the efficacy of IPL delivery of a CP vaccine without a booster. Additional studies were conducted to measure serum immunoglobulin (Ig)Y, mucosal IgA, and histopathology of lungs following vaccination. Delivery of a live CP vaccine by the IPL route, with or without in ovo CpG-ODN, provided significant protection against NE (P < 0.0001). Systemic IgY and mucosal IgA against CP were correlated with protection against NE. There was no necrosis or inflammation in the pulmonary parenchyma. There was a low number of CP isolated from the lungs following live CP delivery by the IPL route. A significant influx of (P < 0.001) of CD8+ T cells and macrophages were noted in the lungs 2 days following live CP delivery by the IPL route. IPL delivery of a live CP vaccine, rather than inactivated CP, provided better protection. This study demonstrated the utility in exploiting the GLA concept in vaccine delivery in broiler chickens.

The role of helper lipids in optimising nanoparticle formulations of self-amplifying RNA

Lipid nanoparticle (LNP) formulation plays a vital role in RNA vaccine delivery. However, further optimisation of self-amplifying RNA (saRNA) vaccine formulation could help enhance seroconversion rates in humans and improve storage stability. Altering either the ionisable or helper lipid can alter the characteristics and performance of formulated saRNA through the interplay of the phospholipid's packing parameter and the geometrical shape within the LNP membrane. In this study, we compared the impact of three helper lipids (DSPC, DOPC, or DOPE) used with two different ionisable lipids (MC3 and C12–200) on stability, transfection efficiency and the inflammation and immunogenicity of saRNA. While helper lipid identity altered saRNA expression across four cell lines in vitro, this was not predictive of an ex vivo or in vivo response. The helper lipid used influenced LNP storage where DSPC provided the best stability profile over four weeks at 2–8 °C. Importantly, helper lipid impact on LNP storage stability was the best predictor of expression in human skin explants, where C12–200 in combination with DSPC provided the most durable expression. C12–200 LNPs also improved protein expression (firefly luciferase) and humoral responses to a SARS-CoV-2 spike saRNA vaccine compared to MC3 LNPs, where the effect of helper lipids was less apparent. Nevertheless, the performance of C12–200 in combination with DSPC appears optimal for saRNA when balancing preferred storage stability requirements against in vivo and ex vivo potency. These data suggest that helper lipid influences the stability and functionality of ionisable lipid nanoparticle-formulated saRNA.

Delivery Systems Developed for Treatment Combinations to Improve Adoptive Cell Therapy.

Adoptive cell therapy (ACT) has shown great success in the clinic for treating hematologic malignancies. However, solid tumor treatment with ACT monotherapy is still challenging, owing to insufficient expansion and rapid exhaustion of adoptive cells, tumor antigen downregulation/loss, and dense tumor extracellular matrix. Delivery strategies for combination cell therapy have great potential to overcome these hurdles. The delivery of vaccines, immune checkpoint inhibitors, cytokines, chemotherapeutics, and photothermal reagents in combination with adoptive cells, have been shown to improve the expansion/activation, decrease exhaustion, and promote the penetration of adoptive cells in solid tumors. Moreover, the delivery of nucleic acids to engineer immune cells directly in vivo holds promise to overcome many of the hurdles associated with the complex ex vivo cell engineering strategies. Here, these research advance, as well as the opportunities and challenges for integrating delivery technologies into cell therapy s are discussed, and the outlook for these emerging areas are criticlly analyzed.

A Comparative Study of Using Poly (D, L, Lactide-co-Glycolic Acid) and Chitosan Nanoparticle as Vaccine Delivery System for a Recombinant Fusion Protein of Newcastle Disease Virus

Introduction: The more effective method of preventing many infectious diseases is vaccination. Numerous infectious diseases that affect both humans and animals have significantly decreased as a result of routine immunization. Aim: The present study aimed to compare the efficacy of in-house built chitosan and Polylactide coglycolic acid (PLGA) nanoparticles coupled with Pichia pastoris expressed immunogenic fusion (F) protein of Newcastle disease (ND). Objectives: Synthesis of biodegradable nanoparticles such as PLGA and chitosan offers a promising opportunity as a vaccine delivery system. Methods: Chitosan nanoparticles and PLGA nanoparticles were synthesized by ionic gelation, and double emulsion solvent evaporation, respectively, and the size was 38.6± 0.84 nm and 320 ±1.5nm, respectively. They demonstrated good epitope integrity of recombinant fusion protein and in vitro release kinetics studies have proved consistent release profile of protein Results: In vivo pathogenicity assay of separately injected nanoparticles has proved no abnormal signs and mortality in chickens. Specific pathogen-free (SPF) chicks were vaccinated with chitosan and PLGA nanoparticles and a recombinant fusion protein of the ND virus. It was demonstrated that PLGA nanoparticles coupled with a fusion protein of Newcastle disease virus conferred a marginally better immune response than chitosan nanoparticles. Comparative study-based results showed that PLGA-based nanoparticles proved a better vaccine delivery vehicle and generated an effective immune response without needing further adjuvants. Conclusion: The present study is a scientific platform for developing the PLGA-based vaccine delivery vehicle to improve immune responses against many infectious diseases.

Political Prioritization of Access to Medicines and Right to Health: Need for an Effective Global Health Governance Through Global Health Diplomacy Comment on "More Pain, More Gain! The Delivery of COVID-19 Vaccines and the Pharmaceutical Industry’s Role in Widening the Access Gap"

Borges and colleagues’ article entitled "More Pain, More Gain! The Delivery of COVID-19 Vaccines and the Pharmaceutical Industry’s Role in Widening the Access Gap," analyzes the role of pharmaceutical companies in providing equitable access to COVID-19 vaccines. They concluded that with the failure of COVID-19 Vaccine Global Access (COVAX), the health gaps have widened due to the profit-driven pharmaceutical sector. In this commentary, we highlight the role of COVAX and its attempt to bridge some access gaps since its inception and the need for reforms in policy-making and global health governance. The commentary highlights the role of global health diplomacy in promoting equity and negotiating the Trade-Related Aspects of Intellectual Property Rights (TRIPS) waiver for COVID-19 vaccines at the World Trade Organization (WTO) thereby promoting global solidarity, global partnerships, access to medicine and health products, and the right to health. We conclude that political prioritization is the key to balance the impact of profit-driven pharma industry and addressing the needs of low- and middle-income countries (LMICs).

Identifying vulnerabilities in essential health services: Analysing the effects of system shocks on childhood vaccination delivery in Lebanon

Shocks effects are under-theorised in the growing literature on health system resilience. Existing work has focused on the effects of single shocks on discrete elements within the health system, typically at national level. Using qualitative system dynamics, we explored how effects of multiple shocks interacted across system levels and combined with existing vulnerabilities to produce effects on essential health services delivery, through the prism of a case study on childhood vaccination in Lebanon. Lebanon has experienced a series of shocks in recent years, including large-scale refugee arrivals from neighbouring Syria, the COVID-19 pandemic and a political-economic crisis. We developed a causal loop diagram (CLD) to explore the effects of each shock individually, and in combination. The CLD was developed and validated using qualitative data from interviews with 38 stakeholders working in Lebanon's vaccination delivery system, in roles ranging from national level policy to facility-level service delivery, conducted between February 2020 and January 2022.We found that each of the shocks had different effects on service demand- and supply-side dynamics. These effects cascaded from national through to local levels. Both Syrian refugee movement and the COVID-19 pandemic primarily exposed vulnerabilities in service demand, mainly through slowly emerging knock-on effects on vaccination uptake behaviour among host communities, and fear of contracting infection in crowded health facilities respectively. The economic crisis exposed wider system vulnerabilities, including demand for vaccination as household income collapsed, and supply-side effects such as reduced clinic time for vaccination, declining workforce retention, and reduced availability of viable vaccine doses, among others. Finally, important pathways of interaction between shocks were identified, particularly affecting the balance between demand for vaccination through publicly supported facilities and private clinics. Future research should incorporate dynamic approaches to identifying within-system vulnerabilities and their potential impacts under different scenarios, as a precursor to improved resilience measurement, system preparedness, and intervention targeting.

Lipid nanoparticle encapsulation of a Delta spike-CD40L DNA vaccine improves effectiveness against Omicron challenge in Syrian hamsters

The effectiveness of mRNA vaccines largely depends on their lipid nanoparticle (LNP) component. Herein, we investigate the effectiveness of DLin-KC2-DMA (KC2) and SM-102-based LNPs for the intramuscular delivery of a plasmid encoding B.1.617.2 (Delta) spike fused with CD40 ligand. LNP encapsulation of this CD40L-adjuvanted DNA vaccine with either LNP formulation drastically enhanced antibody responses, enabling neutralization of heterologous Omicron variants. The DNA-LNP formulations provided excellent protection from homologous challenge, reducing viral replication, and preventing histopathological changes in the pulmonary tissues. Moreover, theDNA-LNP vaccines maintained a high level of protection against heterologous Omicron BA.5 challenge despite a reduced neutralizing response. In addition, we observed that DNA-LNP vaccination led to the pulmonary downregulation of interferon signaling, interleukin-12 signaling, and macrophage response pathways following SARS-CoV-2 challenge, shedding some light on the mechanisms underlying the prevention of pulmonary injury. These results highlight the potential combination of molecular adjuvants with LNP-based vaccine delivery to induce greater and broader immune responses capable of preventing inflammatory damage and protecting against emerging variants. These findings could be informative for the future design of both DNA and mRNA vaccines.

Low-Dose Mildronate-Derived Lipidoids for Efficient mRNA Vaccine Delivery with Minimal Inflammation Side Effects.

mRNA vaccines have been revolutionizing disease prevention and treatment. However, their further application is hindered by inflammatory side effects, primarily caused by delivery systems such as lipid nanoparticles (LNPs). In response to this issue, we prepared cationic lipids (mLPs) derived from mildronate, a small-molecule drug, and subsequently developed the LNP (mLNP-69) comprising a low dose of mLP. Compared with the LNP (sLNP) based on SM-102, a commercially available ionizable lipid, mLNP-69 ensures effective mRNA delivery while significantly reducing local inflammation. In preclinical prophylactic and therapeutic B16-OVA melanoma models, mLNP-69 demonstrated successful mRNA cancer vaccine delivery in vivo, effectively preventing tumor occurrence or impeding tumor progression. The results suggest that the cationic lipids derived from mildronate, which exhibit efficient delivery capabilities and minimal inflammatory side effects, hold great promise for clinical application.

Pandemic Agreement Must Include Levers to Redirect Pharmaceutical Industry Behaviour During Pandemics; Comment on "More Pain, More Gain! The Delivery of COVID-19 Vaccines and the Pharmaceutical Industry’s Role in Widening the Access Gap"

Borges and colleagues rightly argue that an international treaty is needed to curtail the profitdriven behaviour of the pharmaceutical industry during pandemics. The Pandemic Agreement currently being negotiated by Member States of the World Health Organization offers an important opportunity to equip nation states with greater leverage over industry behaviour. In this commentary, we examine the potential of current draft textual proposals for the Pandemic Agreement to redirect pharmaceutical behaviour in future pandemics. However, the future of the Agreement negotiations remains uncertain in the wake of the failure to conclude negotiations in time for the 2024 World Health Assembly. Further, there is limited consensus over proposals that could enable nation states to have greater leverage over industry behaviour. A concerted effort will need to be made to achieve a consensus text that shifts the status quo by giving nation states more power to curtail the self-interest of the pharmaceutical industry.

Polyphenol-Enabled 2D Nanopatch for Enhanced Nasal Mucoadhesion and Immune Activation.

The advancement of effective nasal mucoadhesive delivery faces challenges due to rapid mucociliary clearance (MCC). Conventional studies have employed mucoadhesive materials, mainly forming spherical nanoparticles, but these offer limited adhesion to the nasal mucosa. This study hypothesizes that a 2D nanoscale structure utilizing adhesive polyphenols can provide a superior strategy for countering MCC, aligning with the planar mucosal layers. We explore the use of tannic acid (TA), a polyphenolic molecule known for its adhesive properties and ability to form complexes with biomolecules. Our study introduces an unprecedented 2D nanopatch, assembled through the interaction of TA with green fluorescent protein (GFP), and cell-penetrating peptide (CPP). This 2D nanopatch demonstrates robust adhesion to nasal mucosa and significantly enhances immunoglobulin A secretions, suggesting its potential for enhancing nasal vaccine delivery. The promise of a polyphenol-enabled adhesive 2D nanopatch signifies a pivotal shift from conventional spherical nanoparticles, opening new pathways for delivery strategies through respiratory mucoadhesion.

Improved thermal stabilization of VSV-vector with enhanced vacuum drying in pullulan and trehalose-based films

One major limitation of effective vaccine delivery is its dependency on a robust cold chain infrastructure. While Vesicular stomatitis virus (VSV) has been demonstrated to be an effective viral vaccine vector for diseases including Ebola, its −70 °C storage requirement is a significant limitation for accessing disadvantaged locations and populations. Previous work has shown thermal stabilization of viral vaccines with a combination of pullulan and trehalose (PT) dried films. To improve the thermal stability of VSV, we optimized PT formulation concentrations and components, as well as drying methodology with enhanced vacuum drying. When formulated in PT films, VSV can be stored for 32 weeks at 4 °C with less than 2 log PFU loss, at 25 °C with 2.5 log PFU loss, and at 37 °C with 3.1 log PFU loss. These results demonstrate a significant advancement in VSV thermal stabilization, decreasing the cold chain requirements for VSV vectored vaccines.

Pickering emulsion-guided monomeric delivery of monophosphoryl lipid A for enhanced vaccination

Immunological adjuvants are vaccine components that enhance long-lasting adaptive immune responses to weakly immunogenic antigens. Monophosphoryl lipid A (MPLA) is a potent and safe vaccine adjuvant that initiates an early innate immune response by binding to the Toll-like receptor 4 (TLR4). Importantly, the binding and recognition process is highly dependent on the monomeric state of MPLA. However, current vaccine delivery systems often prioritize improving the loading efficiency of MPLA, while neglecting the need to maintain its monomeric form for optimal immune activation. Here, we introduce a Pickering emulsion-guided MPLA monomeric delivery system (PMMS), which embed MPLA into the oil-water interface to achieve the monomeric loading of MPLA. During interactions with antigen-presenting cells, PMMS functions as a chaperone for MPLA, facilitating efficient recognition by TLR4 regardless of the presence of lipopolysaccharide-binding proteins. At the injection site, PMMS efficiently elicited local immune responses, subsequently promoting the migration of antigen-internalized dendritic cells to the lymph nodes. Within the draining lymph nodes, PMMS enhanced antigen presentation and maturation of dendritic cells. In C57BL/6 mice models, PMMS vaccination provoked potent antigen-specific CD8+ T cell-based immune responses. Additionally, PMMS demonstrated strong anti-tumor effects against E.G7-OVA lymphoma. These data indicate that PMMS provides a straightforward and efficient strategy for delivering monomeric MPLA to achieve robust cellular immune responses and effective cancer immunotherapy.

Effects of hydrogen peroxidase-inactivated vaccine against Streptococcus agalactiae infection in red tilapia (Oreochromis sp.) via different routes of administration

Hydrogen peroxidase-inactivated vaccines have recently developed in controlling infectious diseases in aquaculture. The present study aimed to compare the efficacy of the hydrogen peroxidase-inactivated Streptococcus agalactiae vaccine via different delivery routes (injection, immersion, and oral administration) in red tilapia (Oreochromis sp.) without using adjuvant. Fish were randomly divided into 4 groups including G1: Control treatment (without vaccine), G2: vaccine-based diet (oral administration), G3: vaccinated by immersion and G4: vaccinated by injection. After 6 weeks of the experiment, fish were intraperitoneally injected with S. agalactiae and the mortality was recorded in 14 days. The results showed that lysozyme activity was differentially increased according to the delivery routes of vaccine, organs and time of sampling. However, the specific antibody levels in all vaccinated groups were only increased in week 6 post-vaccination. After the challenge test with S. agalactiae, the serum lysozyme levels in G3 and G4 were significantly higher than the control group (G1), while the total white blood cells and specific antibody levels were significantly increased in G2 and G4 compared to the control (G1). Similarly, the hydrogen peroxidase-inactivated vaccine statistically reduced the cumulative mortality in G2 (35.29%) and G4 (28.95%) compared to G1 (44.12%) after injected with the S. agalactiae. These results showed that the vaccine delivery routes by oral administration or injection may decrease the pathogen and show better protection for red tilapia than the immersion method. Further studies will be investigated to improve the efficacy of hydrogen peroxidaseinactivated vaccine via using different adjuvants.

Design of scalable manufacturing process for the production of biodegradable polymeric microneedles for protein transdermal drug delivery

Introduction. Dissolving polymeric microneedles are attractive drug delivery system especially for vaccine delivery. Still there are a lot of obstacles in developing scalable manufacturing process of them.Aim. To develop a scalable manufacturing process for producing polymeric dissolving microneedles, which can enable keeping protein activity during manufacturing process.Materials and methods. Microneedles were produced from aqua solution of 20 % w.v. pullulan and 3 % w.v. polyvinyl alcohol by casting in hollow negative polyethylene terephthalate mold. Human serum albumin was chosen as a model protein for this investigation.Results and discussion. There were chosen the mode of mold filling and microneedle drying process, which can guarantee keeping of protein activity during manufacturing process.Conclusion. The designed technology can be easily scaled up and used for producing vaccine drug delivery systems, because it doesn’t contain any restraining processes.

Orally dissolving film as a potential vaccine delivery carrier to prevent influenza virus infection

Orally dissolving films (ODF) are designed to be dissolved on the tongue and absorbed in the mouth. It offers multiple advantages over the commonly used needle-based vaccines, especially in terms of convenience allowing safe, painless, and easy self-administration. As the efficacy of ODF-encapsulated influenza vaccines has not been demonstrated, we assessed the protection elicited by inactivated influenza virus (A/PR/8/34, H1N1) vaccine delivered using ODFs in mice. Trehalose and pullulan components of the ODF ensured that the HA antigens of the inactivated PR8 virus retained their stability while ensuring the rapid release of the vaccines upon exposure to murine saliva. Mice were immunized thrice by placing the PR8-ODF on the tongues of mice at 4-week intervals, and vaccine-induced protection was evaluated upon lethal homologous challenge infection. The PR8-ODF vaccination elicited virus-specific serum IgG and IgA antibody responses, hemagglutinin inhibition (HAI), and viral neutralization. Upon challenge infection, ODF vaccination showed higher levels of IgG and IgA antibody responses in the lungs and antibody-secreting cell (ASC) responses in both lung and spleen compared to unimmunized controls. These results corresponded with the enhanced T cell and germinal center B cell responses in the lungs and spleens. Importantly, ODF vaccination significantly reduced lung virus titers and inflammatory cytokines (IFN-γ, IL-6) production compared to unvaccinated control. ODF vaccination ensured 100% survival and prevented weight loss in mice. These findings suggest that influenza vaccine delivery through ODFs could be a promising approach for oral vaccine development.

Avian Influenza Virus A(H5Nx) and Prepandemic Candidate Vaccines: State of the Art.

Avian influenza virus has been long considered the main threat for a future pandemic. Among the possible avian influenza virus subtypes, A(H5N1) clade 2.3.4.4b is becoming enzootic in mammals, representing an alarming step towards a pandemic. In particular, genotype B3.13 has recently caused an outbreak in US dairy cattle. Since pandemic preparedness is largely based on the availability of prepandemic candidate vaccine viruses, in this review we will summarize the current status of the enzootics, and challenges for H5 vaccine manufacturing and delivery.

The Immunomodulatory Effects and Applications of Probiotic Lactiplantibacillus plantarum in Vaccine Development.

Lactiplantibacillus plantarum (previously known as Lactobacillus plantarum) is a lactic acid bacterium that exists in various niches. L. plantarum is a food-grade microorganism that is commonly considered a safe and beneficial microorganism. It is widely used in food fermentation, agricultural enhancement, and environmental protection. L. plantarum is also part of the normal flora that can regulate the intestinal microflora and promote intestinal health. Some strains of L. plantarum are powerful probiotics that induce and modulate the innate and adaptive immune responses. Due to its outstanding immunoregulatory capacities, an increasing number of studies have examined the use of probiotic L. plantarum strains as natural immune adjuvants or alternative live vaccine carriers. The present review summarizes the main immunomodulatory characteristics of L. plantarum and discusses the preliminary immunological effects of L. plantarum as a vaccine adjuvant and delivery carrier. Different methods for improving the immune capacities of recombinant vector vaccines are also discussed.

The drive-through COVID-19 vaccination in Yogyakarta

Introduction: COVID-19 vaccination is the government's priority to control viral transmission. Drive-through system provides quick means of product or service delivery; however, it has not been extensively adopted as a vaccination method. This study aims to describe the implementation of the drive-through COVID-19 vaccination conducted by the Faculty of Medicine, Public Health, and Nursing at Universitas Gadjah Mada in collaboration with several national and regional, governmental and non-governmental institutions. Methods: The drive-through vaccination involved online registration, data collecting, reporting, on-site dose preparation, injection, and post-vaccination monitoring while participants remained in their vehicles. The events were scheduled between July and September 2021 in either FK-KMK UGM Campus or Grha Sabha Pramana, UGM. These venues are on the inner property side of UGM, therefore is no disruption of public traffic. Participants who are eligible and receive an invitation may attend the immunization venue according to the schedule. Results: In ten vaccination events, 20,870 doses of the COVID-19 vaccine were administered. Most participants were young people, with slightly more women than men. The drive-through vaccination went relatively well and offered many benefits such as improving vaccine coverage, time efficiency, social distancing, and herd immunity. Yet, issues like mild Adverse events following immunization and an accumulation of vehicles occurred. Therefore, careful planning and risk anticipation are necessary. Conclusion: The drive-through vaccination generally provides rapid and safe vaccine delivery to large communities. This method could be an alternative to delivering mass vaccinations requiring rapid and extensive coverage.

Prioritising older individuals for COVID-19 booster vaccination leads to optimal public health outcomes in a range of socio-economic settings.

The rapid development of vaccines against SARS-CoV-2 altered the course of the COVID-19 pandemic. In most countries, vaccinations were initially targeted at high-risk populations, including older individuals and healthcare workers. Now, despite substantial infection- and vaccine-induced immunity in host populations worldwide, waning immunity and the emergence of novel variants continue to cause significant waves of infection and disease. Policy makers must determine how to deploy booster vaccinations, particularly when constraints in vaccine supply, delivery and cost mean that booster vaccines cannot be administered to everyone. A key question is therefore whether older individuals should again be prioritised for vaccination, or whether alternative strategies (e.g. offering booster vaccines to the individuals who have most contacts with others and therefore drive infection) can instead offer indirect protection to older individuals. Here, we use mathematical modelling to address this question, considering SARS-CoV-2 transmission in a range of countries with different socio-economic backgrounds. We show that the population structures of different countries can have a pronounced effect on the impact of booster vaccination, even when identical booster vaccination targeting strategies are adopted. However, under the assumed transmission model, prioritising older individuals for booster vaccination consistently leads to the most favourable public health outcomes in every setting considered. This remains true for a range of assumptions about booster vaccine supply and timing, and for different assumed policy objectives of booster vaccination.

Synthesis and Structure Optimization of Star Copolymers as Tunable Macromolecular Carriers for Minimal Immunogen Vaccine Delivery.

Minimal immunogen vaccines are being developed to focus antibody responses against otherwise challenging targets, including human immunodeficiency virus (HIV), but multimerization of the minimal peptide immunogen on a carrier platform is required for activity. Star copolymers comprising multiple hydrophilic polymer chains ("arms") radiating from a central dendrimer unit ("core") were recently reported to be an effective platform for arraying minimal immunogens for inducing antibody responses in mice and primates. However, the impact of different parameters of the star copolymer (e.g., minimal immunogen density and hydrodynamic size) on antibody responses and the optimal synthetic route for controlling those parameters remains to be fully explored. We synthesized a library of star copolymers composed of poly[N-(2-hydroxypropyl)methacrylamide] hydrophilic arms extending from poly(amidoamine) dendrimer cores with the aim of identifying the optimal composition for use as minimal immunogen vaccines. Our results show that the length of the polymer arms has a crucial impact on the star copolymer hydrodynamic size and is precisely tunable over a range of 20-50 nm diameter, while the dendrimer generation affects the maximum number of arms (and therefore minimal immunogens) that can be attached to the surface of the dendrimer. In addition, high-resolution images of selected star copolymer taken by a custom-modified environmental scanning electron microscope enabled the acquisition of high-resolution images, providing new insights into the star copolymer structure. Finally, in vivo studies assessing a star copolymer vaccine comprising an HIV minimal immunogen showed the criticality of polymer arm length in promoting antibody responses and highlighting the importance of composition tunability to yield the desired biological effect.