Intramuscular Vaccination Research Articles

Nanoparticle-Mediated Mucosal Vaccination: Harnessing Nucleic Acids for Immune Enhancement.

Recent advancements in in vitro transcribed mRNA (IVT-mRNA) vaccine manufacturing have attracted considerable interest as advanced methods for combating viral infections. The respiratory mucosa is a primary target for pathogen attack, but traditional intramuscular vaccines are not effective in generating protective ion mucosal surfaces. Mucosal immunization can induce both systemic and mucosal immunity by effectively eliminating microorganisms before their growth and development. However, there are several biological and physical obstacles to the administration of genetic payloads, such as IVT-mRNA and DNA, to the pulmonary and nasal mucosa. Nucleic acid vaccine nanocarriers should effectively protect and load genetic payloads to overcome barriers i.e., biological and physical, at the mucosal sites. This may aid in the transfection of specific antigens, epithelial cells, and incorporation of adjuvants. In this review, we address strategies for delivering genetic payloads, such as nucleic acid vaccines, that have been studied in the past and their potential applications.

Virus-Mimetic Extracellular-Vesicle Vaccine Boosts Systemic and Mucosal Immunity via Immune Recruitment.

Mucosal vaccines can prevent viruses from infecting the respiratory mucosa, rather than only curtailing infection and protecting against the development of disease symptoms. The SARS-CoV-2 spike receptor-binding domain (RBD) is a compelling vaccine target but is undermined by suboptimal mucosal immunogenicity. Here, we report a SARS-CoV-2-mimetic extracellular-vesicle vaccine developed using genetic engineering and dendritic cell membrane budding. After mucosal immunization, the vaccine recruits antigen-presenting cells rapidly initiating a strong innate immune response. Notably, it obviates the need for adjuvants and can induce germinal center formation through both intramuscular and intratracheal vaccination. It not only elicits high levels of RBD-specific antibodies but also stimulates extensive cellular immunity in the respiratory mucosa. A sequential immunization strategy, starting with an intramuscular injection followed by an intratracheal booster, significantly bolsters mucosal immunity with high levels of IgA and tissue-resident memory T cell responses, thereby establishing a formidable defense against pseudovirus infection.

Immunogenic Comparison of Nucleic Acid-Based Vaccines Administered by Pyro-Drive Jet Injector.

mRNA vaccines were successfully developed and approved for emergency use to fight coronavirus disease 2019. However, the effect of DNA vaccines against SARS-CoV-2 is considerably lower than that of mRNA vaccines. A pyro-drive jet injector (PJI) efficiently delivers plasmid DNA intradermally into animal models. Here, we compared the immunogenic potential of DNA and mRNA vaccines in mice using the same platform. PJI was used to deliver naked mRNA and pDNA and their efficacy in inducing antigen expression and immune responses was assessed. Our results showed that PJI efficiently delivered mRNA into the skin, and a smaller effective dose than that of pDNA injection was required to achieve similar levels of antigen expression. The PJI-delivered CpG-free pDNA vaccine efficiently induced antigen-specific antibody production and a cell-mediated IFN-γ response compared to the mRNA vaccine, as well as the upregulation of inflammatory cytokines (IL-6, IFN-γ, and IL-1β) in the skin and lymph nodes. However, the intradermal mRNA vaccine was significantly less immunogenic than the standard intramuscular mRNA-lipid nanoparticle vaccine, despite equivalent mRNA dosages. Improvements in lipid nanoparticle and mRNA technology have revolutionized mRNA vaccines, and DNA vaccines can be similarly modified for higher clinical efficacy.

Cutting-edge research frontiers in oral cavity vaccines for respiratory diseases: a roadmap for scientific advancement.

Intramuscular vaccines present limitations in eliciting robust mucosal immunity and preventing respiratory pathogens transmission. Sublingual vaccine administration offers promising advantages, including interconnected mucosal protection. Despite these advantages, only a few clinical trials have explored sublingual vaccines, underscoring the necessity of optimizing next-generation vaccine formulas. Critical research priorities include understanding vector behavior in the oral environment, understanding their interactions with mucosal immunity and developing formulations enabling sustained mucosal contact to facilitate efficient transduction. Consequently, tonsil organoids, as representative human mucosal models, could offer critical insights into sublingual immunization. Thus, a multi-disciplinary approach integrating pharmacological, immunological, and manufacturing considerations is pivotal for sublingual vaccines in targeting pathogen-aggravated prevalent respiratory diseases including asthma, COPD and lung cancer, as well as the antimicrobial resistance crisis.

Intranasal SARS-CoV-2 Omicron variant vaccines elicit humoral and cellular mucosal immunity in female mice

In order to prevent the emergence and spread of future variants of concern of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), developing vaccines capable of stopping transmission is crucial. The SARS-CoV-2 vaccine NDV-HXP-S can be administered live intranasally (IN) and thus induce protective immunity in the upper respiratory tract. The vaccine is based on Newcastle disease virus (NDV) expressing a stabilised SARS-CoV-2 spike protein. NDV-HXP-S can be produced as influenza virus vaccine at low cost in embryonated chicken eggs. The NDV-HXP-S vaccine was genetically engineered to match the Omicron variants of concern (VOC) BA.1 and BA.5 and tested as an IN two or three dose vaccination regimen in female mice. Furthermore, female mice intramuscularly (IM) vaccinated with mRNA-lipid nanoparticles (LNPs) were IN boosted with NDV-HXP-S. Systemic humoral immunity, memory T cell responses in the lungs and spleens as well as immunoglobulin A (IgA) responses in distinct mucosal tissues were characterised. NDV-HXP-S Omicron variant vaccines elicited high mucosal IgA and serum IgG titers against respective SARS-CoV-2 VOC in female mice following IN administration and protected against challenge from matched variants. Additionally, antigen-specific memory B cells and local T cell responses in the lungs were induced. Host immunity against the NDV vector did not interfere with boosting. Intramuscular vaccination with mRNA-LNPs was enhanced by IN NDV-HXP-S boosting resulting in improvement of serum neutralization titers and induction of mucosal immunity. We demonstrate that NDV-HXP-S Omicron variant vaccines utilised for primary immunizations or boosting efficiently elicit humoral and cellular immunity. The described induction of systemic and mucosal immunity has the potential to reduce infection and transmission. This work was partially funded by the NIAIDCenters of Excellence for Influenza Research and Response (CEIRR) and by the NIAID Collaborative Vaccine Innovation Centers and by institutional funding from the Icahn School of Medicine at Mount Sinai. See under Acknowledgements for details.

Vaccination with Mincle agonist UM-1098 and mycobacterial antigens induces protective Th1 and Th17 responses

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), is one of the top infectious killers in the world. The only licensed vaccine against TB, Bacille Calmette-Guérin (BCG), provides variable protection against pulmonary TB, especially in adults. Hence, novel TB vaccine approaches are urgently needed. Both Th1 and Th17 responses are necessary for protection against TB, yet effective adjuvants and vaccine delivery systems for inducing robust Th1 and Th17 immunity are lacking. Herein we describe a synthetic Mincle agonist, UM-1098, and a silica nanoparticle delivery system that drives Th1/Th17 responses to Mtb antigens. Stimulation of human peripheral blood mononuclear cells (hPBMCs) with UM-1098 induced high levels of Th17 polarizing cytokines IL-6, IL-1β, IL-23 as well as IL-12p70, IL-4 and TNF-α in vitro. PBMCs from both C57BL/6 and BALB/c mice responded with a similar cytokine pattern in vitro and in vivo. Importantly, intramuscular (I.M.) vaccination with UM-1098-adjuvanted TB antigen M72 resulted in significantly higher antigen-specific IFN-γ and IL-17A levels in C57BL/6 wt mice than Mincle KO mice. Vaccination of C57BL/6 wt mice with immunodominant Mtb antigens ESAT6/Ag85B or M72 resulted in predominantly Th1 and Th17 responses and induced antigen-specific serum antibodies. Notably, in a virulent Mtb challenge model, vaccination with UM-1098 adjuvanted ESAT6/Ag85B or M72 significantly reduced lung bacterial burden when compared with unvaccinated mice and protection occurred in the absence of pulmonary inflammation. These data demonstrate that the synthetic Mincle agonist UM-1098 induces strong Th1 and Th17 immunity after vaccination with Mtb antigens and provides protection against Mtb infection in mice.

Efficacy, safety, and immunogenicity of SARS-CoV-2 mRNA vaccine (Omicron BA.5) LVRNA012: a randomized, double-blind, placebo-controlled phase 3 trial.

We aimed to evaluate the efficacy, safety, and immunogenicity of a SARS-CoV-2 mRNA vaccine (Omicron BA.5) LVRNA012 given as the booster in immunized but SARS-CoV-2 infection-free adults in China. This is a single-center, randomized, double-blind, placebo-controlled phase 3 clinical trial enrolling healthy adult participants (≥18 years) who had completed two or three doses of inactivated COVID-19 vaccines at least 6 months before, in Bengbu, Anhui province, China. Eligible participants were randomly assigned (1:1) to receive a booster intramuscular vaccination with an LVRNA012 vaccine (100ug) or placebo. The primary endpoint was the protective efficacy of a booster dose of the LVRNA012 vaccine or placebo against symptomatic COVID-19 of any severity 14 days after vaccination. Laboratory-confirmed COVID-19 infections were identified from 14 days to 180 days after intervention, with active surveillance for symptomatic illness 8 times per month between 7 to 90 days and at least once per month between 90 to 180 days after intervention. 2615 participants were recruited and randomly assigned in a 1:1 ratio to either the vaccine group (1308) or the placebo group (1307). A total of 141 individuals (46 in the LVRNA012 group and 95 in the placebo group) developed symptomatic COVID-19 infection 14 days after the booster immunization, showing a vaccine efficacy of 51.9% (95% CI, 31.3% to 66.4%). Most infections were detected 90 days after intervention during a period when XBB was prevalent in the community. Adverse reactions were reported by 64% of participants after the LVRNA012 vaccination, but most of them were mild or moderate. The booster vaccination with the LVRNA012 mRNA vaccine could significantly enhance neutralizing antibody titers against the Omicron variant XBB.1.5 (GMT 132.3 [99.8, 175.4]) than did those in the placebo group (GMT 12.5 [8.4, 18.7]) at day 14 for the previously immunized individuals. The LVRNA012 mRNA vaccine is immunogenic, and shows robust efficacy in preventing COVID-19 during the omicron-predominate period. ClinicalTrials.gov, identifier NCT05745545.

Exploring Serum Copeptin and Hematological Profile: A Comparative Analysis after Intradermal versus Intramuscular Porcine Reproductive and Respiratory Syndrome Virus Vaccination in Piglets

This study aimed to investigate the impact of intradermal (ID) and intramuscular (IM) vaccination with a porcine reproductive and respiratory syndrome virus (PRRSV)-modified live vaccine (MLV) in piglets on serum copeptin levels and hematological profile. This study included 104 suckling piglets (2 weeks of age) from a commercial farrow-to-finish pig farm suffering from positive unstable PRRSV status. Animals were assigned to four groups, with two replicates (13 piglets/group/replicate); group A: IM vaccination with a PRRSV MLV vaccine, group B: ID vaccination with the same vaccine, group C: ID of Diluvac Forte, and group D: IM of Diluvac Forte. Blood samples were collected from the same three pigs/group/replicate at 4, 7, and 10 weeks of age. Blood samples were used for the performance of the complete blood count, and they were also examined by PCR for PRRSV and by ELISA for copeptin. No significant differences in serum copeptin levels and the number of blood cell counts (packed cell volume—PCV, numbers of white blood cells—WBCs, and platelets number—PLTs) were noticed in the same group over time and among groups. In conclusion, it seems that the vaccination against PRRSV does not affect the levels of the released copeptin. Based on our results, the measurement of serum copeptin could not be proposed as a potential stress biomarker in pigs.

Mitochondrial dysfunction significantly contributes to the sensitivity of tumor cells to anoikis and their metastatic potential

It is well-known that the survival of metastatic cells during their dissemination plays an important role in metastasis. However, does this mean that the final result of the metastatic cascade (the volume of metastatic damage to distant organs and tissues) depends on, or at least correlates with, the degree of resistance to anoikis (distinctive hallmarks of metastatic cells)? This question remains open.The aim of the work was to study in vitro the changes in the survival rates, proliferative activity, oxidative stress, and glycolysis intensity during three days of anchorage-dependent and anchorage-independent growth of two Lewis lung carcinoma cell lines (LLC and LLC/R9) and compare these changes with the status of mitochondria and metastatic potential of the cells in vivo. MethodsThe number and volume of lung metastases were estimated for each cell line after intramuscular inoculation of the cells in C57Bl/6 mice. For the in vitro study, the cells were seeded on Petri dishes pretreated with poly-HEMA or untreated dishes and then allowed to grow for 3 days. Cell viability, cell cycle progression, the level of reactive oxygen species (ROS), glucose consumption and lactate production rates were investigated daily in both growth conditions. An electron microscopy study of intracellular structures was carried out. ResultsThe study showed (as far as we know for the first time) a correlation between the metastatic potential of cells (determined in vivo) and their sensitivity to anoikis (assessed in vitro). The transition of LLC/R9 cells with an inherently defective mitochondrial system to the conditions of anchorage-independent growth was characterized by a decrease in survival, a slowdown in growth rates, an increase in both glucose consumption rate and intracellular ROS levels and manyfold lower metastatic potential, compared to highly metastatic LLC cells with the normal mitochondrial system.

Adverse Effects Related to Paediatric Influenza Vaccination and Its Influence on Vaccination Acceptability. The FLUTETRA Study: A Survey Conducted in the Region of Murcia, Spain.

During the 2022-23 season, three autonomous communities recommended influenza vaccination for all children between 6 and 59 months. The objective is to evaluate the adverse effects associated with the administered influenza vaccines in the Region of Murcia, as well as their influence on the recommendation of the same to acquaintances or repetition in future seasons. Cross-sectional descriptive study with an online questionnaire sent to the parents of vaccinated minors of 6-23 months of age receiving inactivated intramuscular vaccine (IIV) or 24-59 months of age receiving live-attenuated intranasal vaccine (LAIV). Among 4971 surveys received, the most common adverse effect for LAIV and IIV was runny nose (40.90%) and local pain (31.94%), respectively. Sixty percent of adverse effects lasted ≤ 1 day, and around 10% lasted ≥ 3 days. The interference of adverse effects with the minor's daily life was very infrequent (3.32%), as was the need for visiting the medical office (2.68%). Overall, 96.44% of parents would recommend influenza vaccination to friends and relatives after the experience. Only 3.56% would not recommend it, while 1.68% would not vaccinate their child against influenza again. The most frequently cited reason being adverse effects. Our study shows the safety of influenza vaccines. Despite the low impact of adverse effects, they influence some parents in their intention to continue vaccinating or recommending it to acquaintances, which remarks the need to reinforce the information given to parents so that this fact does not influence decision-making.

The Attitudes of Healthcare Professionals in an Autonomous Community in Spain towards Paediatric Influenza Vaccination.

In the 2022-2023 influenza season, three autonomous communities anticipated the document approved by the Public Health Commission recommending influenza vaccination for all children aged 6 to 59 months. The primary objective of this study was to evaluate the attitude of healthcare professionals towards the first universal vaccination campaign in our region, as well as the acceptability of the vaccines used and their attitude towards pilot school vaccination. This was a cross-sectional, survey-based, descriptive study. All healthcare professionals involved in the campaign were invited to participate. Overall, 91.9% of surveyed professionals thought that influenza vaccination from 6 to 59 months was important or very important, and 89.8% had previous experience regarding the intramuscular vaccine. Healthcare professionals rated the intranasal vaccine significantly more positively, but there were no differences when asking about each vaccine without comparison. The inhaled vaccine was preferred by 97.5% for the following campaign. Pilot school vaccination had a 75% acceptance rate. The inhaled vaccine was preferred by most professionals, and pilot school vaccination was highly accepted and independently associated with the importance of vaccination as considered by physicians, being a medical doctor, and participation in the pilot programme.

Reducing Tetanus Vaccine Pain in Filipino Pregnant Women: Helfer Skin Tap Technique Efficacy

Reducing Tetanus Vaccine Pain in Filipino Pregnant Women: Helfer Skin Tap Technique Efficacy

Induction of Superior Systemic and Mucosal Protective Immunity to SARS-CoV-2 by Nasal Administration of a VSV-ΔG-Spike Vaccine.

The emergence of rapidly spreading variants of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) poses a major challenge to vaccines' protective efficacy. Intramuscular (IM) vaccine administration induces short-lived immunity but does not prevent infection and transmission. New vaccination strategies are needed to extend the longevity of vaccine protection, induce mucosal and systemic immunity and prevent viral transmission. The intranasal (IN) administration of the VSV-ΔG-spike vaccine candidate directly to mucosal surfaces yielded superior mucosal and systemic immunity at lower vaccine doses. Compared to IM vaccination in the K18-hACE2 model, IN vaccination preferentially induced mucosal IgA and T-cells, reduced the viral load at the site of infection, and ameliorated disease-associated brain gene expression. IN vaccination was protective even one year after administration. As most of the world population has been vaccinated by IM injection, we demonstrate the potential of a heterologous IM + IN vaccination regimen to induce mucosal immunity while maintaining systemic immunity. Furthermore, the IM + IN regimen prevented virus transmission in a golden Syrian hamster co-caging model. Taken together, we show that IN vaccination with VSV-ΔG-spike, either as a homologous IN + IN regimen or as a boost following IM vaccination, has a favorable potential over IM vaccination in inducing efficient mucosal immunity, long-term protection and preventing virus transmission.

Effects of Repeated Doses of the Vero Cell Vaccine (SARS-Cov-2 Inactivated Vaccine) on Renal Functions in Balb/C Albino Mice.

Many of the vaccines developed for COVID-19 have been approved for clinical emergency use before their safety and preclinical studies have been completed. The main aim of this study was to investigate the effects of an inactivated SARS-CoV-2 virus vaccine (Vero cells) on renal function in Balb/C Albino mice. 21 healthy, 6-8 week old BALB/c male mice were divided into three equal groups, and 0.10 mL of intramuscular saline equal to the vaccine dose volume was administered to the first group. To the second group, a single dose of 0.10 mL 120 U of Vero cell inactive SARS COV-2 vaccine was administered intramuscularly. Group 3 received two consecutive doses of 0.10 mL 120 U intramuscular Vero cell inactive SARS COV-2 vaccine, 14 days apart. After administration, the clinical status, fecal and urine status, nutritional status and kidney histopathology of the mice were evaluated. It was determined that no acute toxic symptoms were observed in the mice administered the vaccine, they were in good condition, and there was no significant stimulatory reaction related to the vaccine in the tissues of the injected local area. There was no difference in feed consumption, water consumption, and body weight gains between the control group, the groups that received a single dose of vaccine, and the groups that received two doses of vaccine (p>0.05). No difference was found between the groups when urine and feces amounts were compared (p>0.05). No difference was found between the groups when urinary urea, creatinine, and serum BUN, creatinine levels were compared (p>0.05). No difference was found in the histopathological evaluation of the kidneys between the groups (p>0.05). In conclusion, single or repeated injections of the SARS-CoV-2 vaccine (Vero cells) into mice were found to have no adverse effects on the animals' overall clinical health, performance abilities and kidneys.

A chimeric adenovirus-vectored vaccine based on Beta spike and Delta RBD confers a broad-spectrum neutralization against Omicron-included SARS-CoV-2 variants.

Urgent research into innovative severe acute respiratory coronavirus-2 (SARS-CoV-2) vaccines that may successfully prevent various emerging emerged variants, particularly the Omicron variant and its subvariants, is necessary. Here, we designed a chimeric adenovirus-vectored vaccine named Ad5-Beta/Delta. This vaccine was created by incorporating the receptor-binding domain from the Delta variant, which has the L452R and T478K mutations, into the complete spike protein of the Beta variant. Both intramuscular (IM) and intranasal (IN) vaccination with Ad5-Beta/Deta vaccine induced robust broad-spectrum neutralization against Omicron BA.5-included variants. IN immunization with Ad5-Beta/Delta vaccine exhibited superior mucosal immunity, manifested by higher secretory IgA antibodies and more tissue-resident memory T cells (TRM) in respiratory tract. The combination of IM and IN delivery of the Ad5-Beta/Delta vaccine was capable of synergically eliciting stronger systemic and mucosal immune responses. Furthermore, the Ad5-Beta/Delta vaccination demonstrated more effective boosting implications after two dosages of mRNA or subunit recombinant protein vaccine, indicating its capacity for utilization as a booster shot in the heterologous vaccination. These outcomes quantified Ad5-Beta/Delta vaccine as a favorable vaccine can provide protective immunity versus SARS-CoV-2 pre-Omicron variants of concern and BA.5-included Omicron subvariants.

Pengaruh Aplikasi Vaksin Dan Suplementasi Probiotik Terhadap Titer Antibodi Dan Pertumbuhan Ayam KUB Yang Dipelihara Di Lingkungan Lahan Kering

The maintenance of chicken livestock is often constrained by several infectious diseases that cause chicken death, one of which is Newcastle Disease. Efficiency in maintaining chicken production can be achieved with probiotics. Probiotic supplementation can reduce the risk of disease and improve chicken health. This study aims to determine the difference in antibody titer of KUB chickens given intramuscular vaccine and drinking water and to know the difference in body weight gain of chickens that get probiotics and those that do not get probiotics. The parameters observed were antibody titer before and after vaccination and body weight gain. This study used the HA and HI test methods. Positive results in the HA test are evenly distributed crystals (diffusion), while negative results in the HA test are flow (tears drop), while the HI test results can be observed by calculating the blood flow that occurs in each well. The results showed that there were significant differences in antibody titers between intramuscular and oral vaccination methods. The provision of probiotics did not show significant differences (P>0.05) on body weight gain of KUB chickens both those who received probiotics and those who did not receive probiotics.

A Pfs48/45-based vaccine to block Plasmodium falciparum transmission: phase 1, open-label, clinical trial

BackgroundThe stalling global progress in malaria control highlights the need for novel tools for malaria elimination, including transmission-blocking vaccines. Transmission-blocking vaccines aim to induce human antibodies that block parasite development in the mosquito and mosquitoes becoming infectious. The Pfs48/45 protein is a leading Plasmodium falciparum transmission-blocking vaccine candidate. The R0.6C fusion protein, consisting of Pfs48/45 domain 3 (6C) and the N-terminal region of P. falciparum glutamate-rich protein (R0), has previously been produced in Lactococcus lactis and elicited functional antibodies in rodents. Here, we assess the safety and transmission-reducing efficacy of R0.6C adsorbed to aluminium hydroxide with and without Matrix-M™ adjuvant in humans.MethodsIn this first-in-human, open-label clinical trial, malaria-naïve adults, aged 18–55 years, were recruited at the Radboudumc in Nijmegen, the Netherlands. Participants received four intramuscular vaccinations on days 0, 28, 56 and 168 with either 30 µg or 100 µg of R0.6C and were randomised for the allocation of one of the two different adjuvant combinations: aluminium hydroxide alone, or aluminium hydroxide combined with Matrix-M1™ adjuvant. Adverse events were recorded from inclusion until 84 days after the fourth vaccination. Anti-R0.6C and anti-6C IgG titres were measured by enzyme-linked immunosorbent assay. Transmission-reducing activity of participants’ serum and purified vaccine-specific immunoglobulin G was assessed by standard membrane feeding assays using laboratory-reared Anopheles stephensi mosquitoes and cultured P. falciparum gametocytes.ResultsThirty-one participants completed four vaccinations and were included in the analysis. Administration of all doses was safe and well-tolerated, with one related grade 3 adverse event (transient fever) and no serious adverse events occurring. Anti-R0.6C and anti-6C IgG titres were similar between the 30 and 100 µg R0.6C arms, but higher in Matrix-M1™ arms. Neat participant sera did not induce significant transmission-reducing activity in mosquito feeding experiments, but concentrated vaccine-specific IgGs purified from sera collected two weeks after the fourth vaccination achieved up to 99% transmission-reducing activity.ConclusionsR0.6C/aluminium hydroxide with or without Matrix-M1™ is safe, immunogenic and induces functional Pfs48/45-specific transmission-blocking antibodies, albeit at insufficient serum concentrations to result in transmission reduction by neat serum. Future work should focus on identifying alternative vaccine formulations or regimens that enhance functional antibody responses.Trial registrationThe trial is registered with ClinicalTrials.gov under identifier NCT04862416.

Mucosal immunization with a low-energy electron inactivated respiratory syncytial virus vaccine protects mice without Th2 immune bias.

The respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory tract infections associated with numerous hospitalizations. Recently, intramuscular (i.m.) vaccines against RSV have been approved for elderly and pregnant women. Noninvasive mucosal vaccination, e.g., by inhalation, offers an alternative against respiratory pathogens like RSV. Effective mucosal vaccines induce local immune responses, potentially resulting in the efficient and fast elimination of respiratory viruses after natural infection. To investigate this immune response to an RSV challenge, low-energy electron inactivated RSV (LEEI-RSV) was formulated with phosphatidylcholine-liposomes (PC-LEEI-RSV) or 1,2-dioleoyl-3-trimethylammonium-propane and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DD-LEEI-RSV) for vaccination of mice intranasally. As controls, LEEI-RSV and formalin-inactivated-RSV (FI-RSV) were used via i.m. vaccination. The RSV-specific immunogenicity of the different vaccines and their protective efficacy were analyzed. RSV-specific IgA antibodies and a statistically significant reduction in viral load upon challenge were detected in mucosal DD-LEEI-RSV-vaccinated animals. Alhydrogel-adjuvanted LEEI-RSV i.m. showed a Th2-bias with enhanced IgE, eosinophils, and lung histopathology comparable to FI-RSV. These effects were absent when applying the mucosal vaccines highlighting the potential of DD-LEEI-RSV as an RSV vaccine candidate and the improved performance of this mucosal vaccine candidate.

419 Intramuscular immunization with rVCG-MECA vaccine elicits stronger chlamydial specific immune response than intranasal immunization

OBJECTIVES/GOALS: We prioritize Chlamydia’s public health impact, aim to develop rVCG-MECA for practical use, study robust immunity for effective strategies, and assess animal models for human vaccination adaptation. Our work highlights rVCG-MECA’s translational significance in public health. METHODS/STUDY POPULATION: Female Mice C57BL/6J mice (N=8) were immunized intramuscularly(IM) and intranasally(IN) and boosted twice, two weeks apart, with rVCG-MECA, once with live Chlamydia (C. trachomatis serovar D elementary bodies) and PBS. Specific mucosal and systemic immune responses were characterized. Vaccine efficacy was determined from chlamydia shedding following the transcervical challenge. Additionally, Chlamydia-specific cytokine (IFN-γ and IL-4) production by splenic and ILN T cells was assessed after 16 weeks RESULTS/ANTICIPATED RESULTS: Immunization with rVCG-MECA via intramuscular and intranasal routes triggered notable humoral responses in systemic and mucosal tissues. Intramuscular vaccination produced higher IgG2c levels in both tissues, while intranasal vaccination led to elevated IgA levels in mucosal tissues. rVCG-MECA-immunized mice exhibited significantly higher IFN-γ (Th1) secretion compared to IL-4 (Th2), with intramuscular immunization showing the highest IFN-γ levels. These findings anticipate robust immune responses, promising protection against Chlamydia, particularly through the intra muscular route. Overall, our results support rVCG-MECA as a promising Chlamydia vaccine, aligned with public health goals. DISCUSSION/SIGNIFICANCE: This study suggests that IM and IN immunization with rVCG-MECA induces immune effectors such as IFN-gamma and IgG2c that mediate chlamydial clearance in the genetical tract.

SARS-CoV-2-specific mucosal immune response in vaccinated versus infected children.

The anti-COVID-19 intramuscular vaccination induces a strong systemic but a weak mucosal immune response in adults. Little is known about the mucosal immune response in children infected or vaccinated against SARS-CoV-2. We found that 28% of children had detectable salivary IgA against SARS-CoV-2 even before vaccination, suggesting that, in children, SARS-CoV-2 infection may be undiagnosed. After vaccination, only receptor-binding domain (RBD)-specific IgA1 significantly increased in the saliva. Conversely, infected children had significantly higher salivary RBD-IgA2 compared to IgA1, indicating that infection more than vaccination induces a specific mucosal immune response in children. Future efforts should focus on development of vaccine technologies that also activate mucosal immunity.