Search Results (179)

Background/Objectives: Vaccine immunogenicity is often suboptimal in vulnerable populations such as the elderly, infants, and individuals in low- and middle-income countries. One contributing factor may be pre-existing immunomodulatory conditions, including helminth infections. This study investigates the impact of Fasciola hepatica (F. hepatica) derived molecules on the early humoral response to the COVID-19 mRNA vaccine Comirnaty^® in a mouse model. Methods: BALB/c mice were pretreated with a F. hepatica protein extract (FH) or complete Freund’s adjuvant (CFA) prior to vaccination. Cytokine production and antibody responses were assessed at 0, 14, and 21 days post-vaccination (dpv) through serum analysis and ex vivo splenocyte stimulation with the SARS-CoV-2 receptor-binding domain (RBD) or LPS. Results: At 0 dpv, FH-treated mice showed increased serum IL-10, while CFA treatment induced IL-12. FH- but not CFA-treated splenocytes secreted IL-10 upon RBD or LPS stimulation. At 21 dpv, FH-treated mice lacked IFN-γ production but maintained IL-10 and showed elevated IL-4, consistent with a Th2-skewed profile. Although total anti-RBD IgG levels were similar between groups, FH-treated mice exhibited reduced IgG avidity and a higher IgG1/IgG2 ratio. CFA-treated mice showed delayed avidity maturation. Conclusions: Prior exposure to F. hepatica antigens can modulate the early immune response to Comirnaty^®, affecting both cellular activation and antibody quality. This altered response may reflect a reduced early protective capacity of the vaccine, which might need to be considered when designing or evaluating vaccination strategies using mRNA vaccines in helminth-endemic regions. Full article

Background: Lipid nanoparticles (LNPs) have proven effective in delivering RNA-based modalities. Rapid approval of the COVID-19 vaccines highlights the promise of LNPs as a delivery platform for nucleic acid-based therapies and vaccines. Nevertheless, improved LNP designs are needed to advance next-generation vaccines and other gene therapies toward greater clinical success. Lipid components and LNP formulation excipients play a central role in biodistribution, immunogenicity, and stability. Therefore, it is important to understand, identify, and assess the appropriate lipid components for developing a safe and effective formulation. Herein, this study focused on developing a novel Polysorbate-80 (PS-80)-based LNP. We hypothesized that substituting conventional linear PEG-lipids with PS-80, a widely used, biocompatible injectable surfactant featuring a branched PEG-like structure, may change the LNPs biodistribution pattern and enhance long-term stability. By leveraging PS-80’s unique structural properties, this study aimed to develop an mRNA-LNP platform with improved extrahepatic delivery and robust freeze/thaw tolerance. Methods: We employed a stepwise optimization to establish both the lipid composition and formulation buffer to yield a stable, high-performing PS-80-based SARS-CoV-2 mRNA-LNP (SC2-PS80 LNP). We compared phosphate- versus tris-based buffers for long-term stability, examined multiple lipid ratios, and evaluated the impact of incorporating PS-80 (a branched PEG-lipid) on in vivo biodistribution. Various analytical assays were performed to assess particle size, encapsulation efficiency, mRNA purity, and in vitro potency of the developed formulation and a humanized mouse model was used to measure its immunogenicity over six months of storage at −80 °C. Results: Replacing the standard 1,2-dimyristoyl-rac-glycero-3-methoxy polyethylene glycol-2000 (PEG-DMG) lipid with PS-80 increased spleen-specific expression of the mRNA-LNPs after intramuscular injection. Formulating in a tris-sucrose-salt (TSS) buffer preserved the LNP’s physicochemical properties and in vitro potency over six months at −80 °C, whereas a conventional PBS-sucrose (PSS) buffer was less protective under frozen conditions. Notably, TSS-based SC2-PS80 LNPs elicited potent humoral immunity in mice, including high anti-spike IgG titers and robust pseudovirus neutralization, comparable to freshly prepared formulations. Conclusions: A PS-80-based mRNA-LNP platform formulated in TSS buffer confers improved extrahepatic delivery, long-term frozen stability, and strong immunogenicity against SARS-CoV-2 following six months. These findings offer a promising pathway for the design of next-generation mRNA vaccines and therapeutics with enhanced stability and clinical potential. Full article

Background: As COVID-19 has become an epidemic, we conducted an open-label study aimed to identify immunogenicity and reactogenicity of boosters of the BNT162b2 vaccine in a real-world cohort of long-survivor metastatic lung cancer patients (LS-mLC pts). Methods and Analysis: According to the timing of the booster dose (BD) and SARS-CoV-2 infection (Cov-I) during anticancer treatment (ACT), between October 2021 and February 2022, we prospectively enrolled 166 cancer patients into five parallel cohorts. The primary endpoints were seroprevalence of IgG Anti-spike-RBD (anti-S IgG) at two pre-defined timepoints (T1: +30–90 days after BD; T2: +6 months +/− 4 weeks after BD). As an exploratory endpoint, we compared the median pre-vaccination value of four cytokines (IL-6, IL-2R, TNF-α, IL-10) with post-BD values in immunotherapy-treated pts (IO-pts). Results: The anti-S IgG seropositivity rate was 100% at T1 and 98.8% at T2. After 6 months, hybrid immunisation was associated with a higher median anti-S IgG titre compared to vaccine-alone-induced seroconversion (p < 0.0001). In uninfected pts, the median anti-S IgG titre was significantly lower in IO-pts compared to non-IO-pts (p = 0.02); no difference was found when comparing myelosuppressive or not ACT. Among the 68 IO-pts, 5 pts (7.3%) showed a significant increase (≥1.5 fold) of at least two cytokines in post-BD samples, without reporting ir-AEs. Conclusions: Boosters of the COVID-19 mRNA vaccine were effective and safe. In IO-pts without recent Cov-I, additional BDs should be considered to prolong serological immunity. Full article

Background/Objectives: mRNA vaccines have demonstrated strong immunogenicity and efficacy against SARS-CoV-2. However, the extent of antibody cross-reactivity against human seasonal coronaviruses, such as NL63, remains unclear. Furthermore, it is unknown whether pre-existing antibody responses against NL63 might influence the outcome of SARS-CoV-2 mRNA vaccination. Methods: We used a flow cytometry-based serological assay and an in vitro neutralization assay to analyze NL63 antibody responses in sera from SARS-CoV-2 mRNA-vaccinated mice and plasma samples from a vaccinated human cohort. Results: We found that the Moderna mRNA-1273 vaccine can generate cross-reactive antibodies against NL63. Importantly, SARS-CoV-2 mRNA vaccination did not boost pre-existing anti-NL63 responses in humans, and pre-existing NL63 antibody levels did not affect the antibody response induced by SARS-CoV-2 mRNA vaccination. Conclusions: These findings suggest that while SARS-CoV-2 mRNA vaccination can induce cross-reactive antibodies against NL63, pre-existing immunity to this seasonal coronavirus does not appear to significantly impact vaccine immunogenicity. These findings contribute to our understanding of the complex interplay between pre-existing immunity to seasonal coronaviruses and the immune response generated by SARS-CoV-2 mRNA vaccines. Full article

Introduction: Inflammatory bowel diseases (IBDs) require immunosuppressive drugs like biologics. All IBD patients, including those on biological therapy, should be vaccinated against COVID-19, according to the ECCO recommendations. IBD patients on anti-TNF treatment exhibited lower COVID-19 vaccine responses; however, SARS-CoV-2 variant neutralizing antibody titers have been seldom studied. Methods: IBD patients and healthcare professionals (control group) were tested for COVID-19 vaccine immunogenicity by neutralizing antibody titers against Wild-Type SARS-CoV-2 and its variants. IBD patients were assigned to no treatment/mesalamine, anti-TNF biologic therapy, or non-anti-TNF biologic therapy. The study was performed in a tertiary hospital in Palermo, Sicily, from May to July 2021. Results: In total, 107 IBD patients and 41 healthcare workers were enrolled. A total of 46 patients received mesalamine or no medication, 28 received anti-TNF biologics, and 33 received non-anti-TNF biologics. No significant differences were found in age, gender, or timing of blood sampling post vaccination. Omicron neutralizing activity was markedly reduced in all groups (p < 0.001). The group of patients on anti-TNF biologics showed lower neutralizing antibody titers against Alpha, Delta, and Gamma strains than every other group analyzed. Conclusions: IBD patients on anti-TNF drugs have a reduced serological response to the SARS-CoV-2 vaccine, with the Omicron variant not being neutralized. This highlights the necessity for tailored vaccine strategies for these patients. Full article

Background/Objectives: Novel mRNA vaccines have been successfully utilized to curtail the SARS-CoV-2 pandemic. However, the immunology underlying CoV2 vaccinations, particularly with repeated boosting, has not been properly characterized due to limitations in the preclinical modeling of SARS-CoV-2 infection/vaccinations as well as constantly changing vaccine formulations. The immunoregulatory aspects involved in such vaccine approaches remain unclear. Antibodies, due to inherent immunogenicity by VDJ gene rearrangement, have the potential to induce antibodies directed towards them called anti-idiotype antibodies, which can play a downregulatory role in responses. The paratope of some of these anti-idiotype antibodies can also act as a mirror to the original antigen, which, in the case of SARS-CoV-2 vaccines, would be to the spike protein and, therefore, also be capable of binding its target, ACE2, potentially causing adverse effects. Methods: To investigate if sequential SARS-CoV-2 mRNA vaccination can induce anti-idiotype antibody responses, K18 hACE2 transgenic mice were serially vaccinated with a SARS-CoV-2 mRNA construct to determine the kinetics of anti-spike and anti-ACE2 responses via custom-made ELISAs. Results: While sequential vaccination produced robust anti-spike responses, anti-ACE2 levels were also detected and gradually amplified with each boost. These anti-ACE2 antibodies persisted for 3 months after the final vaccination and showed evidence of hACE2 binding, as levels were lower in K18 mice in comparison to the wild type. Conclusions: These data would suggest that sequential SARS-CoV-2 mRNA vaccination has the potential to induce anti-ACE2 antibodies in mice, with each boost amplifying the amount of antibody. Full article

Background: The majority of antigen-based SARS-CoV-2 (SCV2) vaccines utilized in the clinic have had the Spike protein or domains thereof as the immunogen. While the Spike protein is highly immunogenic, it is also subject to genetic drift over time, which has led to a series of variants of concern that continue to evolve, requiring yearly updates to the vaccine formulations. In this study, we investigate the potential of the N-terminal ectodomain of the ORF3a protein encoded by the orf3a gene of SCV2 to be an evolution-resistant vaccine antigen. This domain is highly conserved over time, and, unlike many other SCV2 conserved proteins, it is present on the exterior of the virion, making it accessible to antibodies. ORF3a is also important for eliciting robust anti-SARS-CoV-2 T-cell responses. Methods: We designed a DNA vaccine by fusing the N-terminal ectodomain of orf3a to macrophage-inflammatory protein 3α (MIP3α), which is a chemokine utilized in our laboratory that enhances vaccine immunogenicity by targeting an antigen to its receptor CCR6 present on immature dendritic cells. The DNA vaccine was tested in mouse immunogenicity studies, vaccinating by intramuscular (IM) electroporation and by intranasal (IN) with CpG adjuvant administrations. We also tested a peptide vaccine fusing amino acids 15–28 of the ectodomain to immunogenic carrier protein KLH, adjuvanted with Addavax. Results: The DNA IM route was able to induce 3a-specific splenic T-cell responses, showing proof of principle that the region can be immunogenic. The DNA IN route further showed that we could induce ORF3a-specific T-cell responses in the lung, which are critical for potential disease mitigation. The peptide vaccine elicited a robust anti-ORF3a antibody response systemically, as well as in the mucosa of the lungs and sinus cavity. Conclusions: These studies collectively show that this evolutionarily stable region can be targeted by vaccination strategies, and future work will test if these vaccines, alone or in combination, can result in reduced disease burden in animal challenge models. Full article

Background/Objectives: Virus-like particles (VLPs) represent an attractive platform for delivering vaccine formulations, combining a high biosafety profile with a potent immune-stimulatory ability. VLPs are non-infectious, non-replicating, self-assembling nanostructures that can be exploited to efficiently expose membrane-tethered glycoproteins such as the SARS-CoV-2 Spike (S) protein, the main target of approved preventive vaccines. Here, we describe the development and preclinical validation of Simian Immunodeficiency Virus (SIV)-based GFP-labeled VLPs displaying S from the B.1.617.2 (Delta) variant (VLP/S-Delta) for inducing persistent anti-SARS-CoV-2 neutralizing antibodies (nAbs) and S-specific T cell responses in mice. Methods: SIV-derived VLP/S-Delta were produced by co-transfecting a plasmid expressing SIVGag-GFP, required for VLP assembly and quantification by flow virometry, a plasmid encoding the Delta S protein deleted in the cytoplasmic tail (CT), to improve membrane binding, and a VSV.G-expressing plasmid, to enhance VLP uptake. Recovered VLPs were titrated by flow virometry and characterized in vitro by transmission electron microscopy (TEM) and confocal microscopy (CLSM). BALB/c mice were immunized intramuscularly with VLP/S-Delta following a prime–boost regimen, and humoral and cellular immune responses were assessed. Results: VLP/S-Delta were efficiently pseudotyped with CT-truncated S-Delta. After BALB/c priming, VLP/S-Delta elicited both specific anti-RBD IgGs and anti-Delta nAbs that significantly increased after the boost and were maintained over time. The prime–boost vaccination induced similar levels of cross-nAbs against the ancestral Wuhan-Hu-1 strain as well as cross-nAbs against Omicron BA.1, BA.2 and BA.4/5 VoCs, albeit at lower levels. Moreover, immunization with VLP/S-Delta induced S-specific IFNγ-producing T cells. Conclusions: These data suggest that SIV-based VLPs are an appropriate delivery system for the elicitation of efficient and sustained humoral and cellular immunity in mice, paving the way for further improvements in the immunogen design to enhance the quality and breadth of immune responses against different viral glycoproteins. Full article

Background: IgG4 is the least immunogenic subclass of IgG. Immunization with mRNA vaccines against SARS-CoV-2, unlike other vaccines, induces an increase in IgG4 against the spike protein in healthy populations. This study investigated whether immunosuppressive therapy affects the immune response, focusing on IgG subclass changes, to four doses of mRNA vaccine in kidney transplant recipients (KTRs). Methods: This study includes 146 KTRs and 23 dialysis patients (DPs) who received three mRNA-1273 vaccine doses and a BNT162b2 booster. We evaluated anti-spike IgG titers and subclasses, T-CD4+ and T-CD8+ cellular responses, and serum neutralizing activity (SNA). Results: At the fourth dose, 75.8% of COVID-19 naïve KTRs developed humoral and cellular responses (vs. 95.7% in DPs). There was a correlation between anti-spike IgG titers/subclasses and SNA (p < 0.001). IgG subclass kinetics after the third/fourth dose differed between COVID-19 naïve KTRs and DPs. Immunosuppressive therapy influenced IgG subclasses: mTOR inhibitors (mTORi) positively influenced IgG1 and IgG3 (p < 0.05), while mycophenolic acid negatively affected IgG1, IgG3, and IgG4 (p < 0.05). SNA is correlated with breakthrough infections after four doses of vaccine in KTRs. mTORi was the only factor associated with SNA > 65% in naïve KTRs [4.29 (1.21–15.17), p = 0.024]. Conclusions: KTRs show weaker cellular and humoral immune responses to mRNA vaccines and a class shift towards non-inflammatory anti-S IgG4 upon booster doses. IgG subclasses show a positive correlation with SNA and are influenced by immunosuppression. Increased SNA after four doses of vaccine is protective against infection. mTORi may benefit non-responding KTRs. Full article

The first infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes the coronavirus disease 2019 (COVID-19), occurred in December 2019. Within a single month, the disease reached other countries, spreading in a rapid and generalized manner worldwide to cause the COVID-19 pandemic. In Brazil, the number of COVID-19 cases surpassed 38 million. This study was conducted to produce antibodies against SARS-CoV-2 and investigate the immunogenic potential of synthetic peptides containing partial sequences of the main proteins (spike, membrane, and nucleocapsid proteins). In addition, we evaluated the ability of the antibodies to impair the interaction between the spike S1 protein and human ACE-2 protein, which is the main route of entry of the virus into host cells. By immunizing horses with synthetic peptides, we obtained hyperimmune sera with specific anti-SARS-CoV-2 antibodies, which were fragmented to release the F(ab’)2 portion that binds to the different SARS-CoV-2 proteins as a recombinant S1-protein and proteins from a viral lysate. The other F(ab’)2 samples also impaired the interaction between S1 protein and ACE-2 proteins, showing high potential to prevent viral spreading. Full article

Background: The Safety and Immunogenicity of COVID-19 Vaccines in Systemic Autoimmune-Mediated Inflammatory Diseases (SUCCEED) study was created to better understand COVID-19 vaccination in immune-mediated inflammatory disease (IMID). Knowing the frequency of COVID-19 breakthrough infections is important, particularly in IMID. Our objective was to assess these events in IMID. Methods: We prospectively studied IMID participants who had received ≥three COVID-19 vaccine doses. Individuals provided saliva samples monthly (September 2022 to August 2023). These were evaluated by polymerase chain reaction (PCR) for SARS-CoV-2. We also assessed antibodies against SARS-CoV-2 (anti-spike, SmT1, receptor binding domain, RBD, and nucleocapsid, NP) based on dried blood spots. Multivariable general estimating equation regression produced odd ratios (OR) for PCR SARS-CoV-2 positivity, related to demographics, immunosuppressives, and antibody levels. Results: Diagnoses included rheumatoid arthritis RA (N = 161, 44% of the total), systemic lupus, psoriatic arthritis, spondylarthritis, vasculitis, systemic sclerosis, and inflammatory bowel disease. Of the 366 participants, most were taking immunosuppressive medication. Of 1266 saliva samples, 56 (5.1%) were positive for SARS-CoV-2 on PCR. Higher anti-SmT1 antibodies were inversely associated with SARS-CoV-2 detection on PCR (adjusted OR 0.66, 95% confidence interval 0.45–0.97). Antibodies to SmT1, RBD, and NP were correlated and thus could not be included in a single model, but when anti-RBD was used in place of anti-SmT1, the results were similar. No other factor (including prior COVID-19 infection) was clearly associated with SARS-CoV-2 detection. Conclusions: This is the first study of SARS-CoV-2 in a large prospective cohort of triple (or more) vaccinated individuals with IMIDs. Anti-SmT1 antibodies appeared to be protective against later SARS-CoV-2 positivity, although recent past infection was not clearly related. This suggests the importance of maintaining robust vaccine-induced immunity through vaccination in IMID. Full article

The emergence of new variants and diverse vaccination regimens have raised uncertainty about vaccine effectiveness against SARS-CoV-2. This study aims to investigate the impact of Omicron primo-/reinfection and primary vaccination schedules on the immunogenicity of an mRNA-based booster dose over a six-month period. We conducted a prospective cohort study to assess the durability and level of antibodies of 678 healthcare workers fully vaccinated against COVID-19. They were categorized based on their primary vaccination regimen. Blood samples were collected before the booster dose and 1 and 6 months after. Significant Anti-S-RBD differences were found between previously infected and naïve volunteers (p = 0.01). Considering the initial vaccine schedules, mRNA-based vaccines displayed significant higher antibody production and longer persistence among both infected and naïve participants. After the booster dose, participants primoinfected with the Omicron variant exhibited higher antibody concentrations than those who experienced reinfection, even after 6 months of follow-up (22,545 and 9460 U/mL, respectively). Moreover, these groups showed the most pronounced disparity in antibody titers ratios between infected and uninfected individuals. Overall, the booster dose failed to enhance humoral response in individuals reinfected with the Omicron variant after receiving it. Hybrid immunity and mRNA-based vaccine initial schedules showed higher levels and longer persistence of antibodies. Full article

Background: A broad-spectrum anti-SARS-CoV-2 monoclonal antibody (mAb), SA55, is highly effective against SARS-CoV-2 variants. This trial aimed at demonstrating the safety, tolerability, local drug retention and neutralizing activity, systemic exposure level, and immunogenicity of the SA55 nasal spray in healthy individuals. Methods: This phase I, dose-escalation clinical trial combined an open-label design with a randomized, controlled, double-blind design. Healthy participants aged 18–65 years were enrolled and received a single dose of the SA55 nasal spray (1 mg or 2 mg) or multiple doses of SA55 nasal spray/placebo for 7 days (1 or 2 mg/dose, 3 or 6 doses/day). Safety monitoring was conducted throughout the study. Nasal swabs and venous blood samples were collected to analyze local drug concentration/neutralization, systemic exposure, and immunogenicity. Results: From 2 June to 11 August 2023, 80 participants were enrolled and received study intervention. The severity of adverse reactions (ADRs) reported during the study was mild in all cases, and all ADRs were laboratory test abnormalities without corresponding symptoms or vital signs. A total of 9 ADRs were reported, of which all were mild in severity. Overall ADR incidence rate was 16.67% (8/48) in single-dose groups and 4.17% (1/24) in multiple-dose groups. The nasal local drug concentration and neutralizing activity were generally stable within 4–8 h, with favorable neutralization activity against Omicron BF.7 and XBB strains. Conclusions: This study demonstrated favorable safety and tolerability of the SA55 nasal spray in healthy volunteers, exhibited satisfactory neutralizing activity against Omicron variants intranasally, and indicated low systemic toxicity risk. Full article

Background/Objectives: The emergence of the Omicron variant has complicated COVID-19 control and prompted vaccine updates. Recent studies have shown that a fourth dose significantly protects against infection and severe disease, though long-term immunity data remain limited. This study aimed to assess Anti-S-RBD antibodies and interferon-γ levels in healthcare workers 12 months after receiving bivalent Original/Omicron BA.4-5 fourth SARS-CoV-2 vaccine. Methods: In this prospective cohort study, 549 healthcare workers were categorized by the initial vaccination schedule, with 229 individuals having received the fourth SARS-CoV-2 vaccine dose. Blood samples were collected from all participants 12 months post-vaccination. Results: Significant differences in Anti-S-RBD antibody levels were observed between those receiving a fourth dose and those who did not, while no differences were seen in interferon-γ levels. After 12 months, there were no significant differences in humoral and cellular immunity response between volunteers primoinfected or reinfected across different periods by the Omicron variant. A multivariable analysis revealed an association between high antibody levels (>6000 U/mL) and interferon-γ levels (OR: 3.13; 95% CI: 1.3–7.7; p < 0.05). Regarding primary vaccine schedules, participants vaccinated with ChAdOx1 (a single or double dose) had notably lower antibody levels compared to those who received mRNA-based vaccines. Additionally, the study shows a higher frequency of multiple infections among those with a single-dose ChAdOx1 primary schedule (OR: 6.24; 95% CI: 1.25–31.15; p < 0.01). Conclusions: Overall, mRNA-based vaccines exhibited stronger long-term immunogenicity. Repeated exposure to the Omicron variant seems to mitigate immune imprinting from the wild-type SARS-CoV-2. An association was observed between high antibody levels and a strong cellular response, although the correlation was not linear. Full article

HIV causes intense polyclonal activation of B cells, resulting in increased numbers of spontaneously antibody-secreting cells in the circulation and hypergammaglobulinemia. It is accompanied by significant perturbations in various B cell subsets, such as increased frequencies of immature/transitional B cells, activated memory B cells, atypical memory B cells, short-lived plasmablasts and regulatory B cells, as well as by decreased frequencies of resting memory and resting naïve B cells. Furthermore, both memory and antigen-inexperienced naïve B cells show exhausted and immune-senescent phenotypes. HIV also drives the expansion and functional impairment of CD4⁺ T follicular helper cells, which provide help to B cells, crucial for the generation of germinal center reactions and production of long-lived plasma and memory B cells. By suppressing viral replication, anti-retroviral therapy reverses the virus-induced perturbations and functional defects, albeit inadequately. Due to HIV’s lingering impact on B cells, immune senescence and residual chronic inflammation, people with HIV (PWH), especially immune non-responders, are immunocompromised and mount suboptimal antibody responses to vaccination for SARS-CoV-2. Here, we review how functionally and phenotypically distinct B cell subsets are induced in response to a vaccine and an infection and how HIV infection and anti-retroviral therapy (ART) impact them. We also review the role played by HIV-induced defects and perturbations in B cells in the induction of humoral immune responses to currently used anti-SARS-CoV-2 vaccines in PWH on ART. We also outline different strategies that could potentially enhance the vaccine-induced antibody responses in PWH. The review will provide guidance and impetus for further research to improve the immunogenicity of these vaccines in this human population. Full article