The effect of antigen dose on T cell-targeting vaccine outcome

Augmenting vaccine efficacy: Tailored immune strategy with alum-stabilized Pickering emulsion

BACKGROUND

The achievement of optimal vaccine efficacy is contingent upon the collaborative interactions between T and B cells in adaptive immunity. Although multiple immunization strategies have been proposed, there is a notable scarcity of comprehensive investigations pertaining to enhance immune effects through immune strategy adjustments for individual vaccine.

METHODS

The hierarchically structured aluminum hydroxide microgel-stabilized Pickering emulsion (ASPE) was prepared by ultrasonic method. This study explored the influence of the immune strategy of ASPE to immune responses, including antigen exposure pattern, adjuvants and antigen dosage, and administration interval.

RESULTS

The findings revealed that external antigen adsorption facilitated increased exposure of antigen epitopes, leading to elevated IgG titers and secretion of cytokines such as interferon-gamma (IFN-γ) or interleukin-4 (IL-4). Additionally, even a low dose (1 μg/dose) of antigens of ASPE boosted sufficient neutralizing antibody levels and memory T cells compared to high-dose antigens, which consistent with the adjuvant dosage effect. Furthermore, maintaining a 4-week immunization interval yielded optimal levels of antigen-specific IgG titers in both short-term and long-term scenarios, as compared to intervals of 2, 3, and 5 weeks. A consistent trend was observed in the proliferation of memory B cells, reaching a superior level at the 4-week interval, which could enhance protection against viral re-infection.

CONCLUSION

Tailoring immunization strategies for specific vaccines has emerged as powerful driver in maximizing vaccine efficacy and eliciting robust immune responses, thereby presenting cutting-edge approaches to enhanced vaccination.

Advances in Therapeutic Cancer Vaccines, Their Obstacles, and Prospects Toward Tumor Immunotherapy

Over the past few decades, cancer immunotherapy has experienced a significant revolution due to the advancements in immune checkpoint inhibitors (ICIs) and adoptive cell therapies (ACTs), along with their regulatory approvals. In recent times, there has been hope in the effectiveness of cancer vaccines for therapy as they have been able to stimulate de novo T-cell reactions against tumor antigens. These tumor antigens include both tumor-associated antigen (TAA) and tumor-specific antigen (TSA). Nevertheless, the constant quest to fully achieve these abilities persists. Therefore, this review offers a broad perspective on the existing status of cancer immunizations. Cancer vaccine design has been revolutionized due to the advancements made in antigen selection, the development of antigen delivery systems, and a deeper understanding of the strategic intricacies involved in effective antigen presentation. In addition, this review addresses the present condition of clinical tests and deliberates on their approaches, with a particular emphasis on the immunogenicity specific to tumors and the evaluation of effectiveness against tumors. Nevertheless, the ongoing clinical endeavors to create cancer vaccines have failed to produce remarkable clinical results as a result of substantial obstacles, such as the suppression of the tumor immune microenvironment, the identification of suitable candidates, the assessment of immune responses, and the acceleration of vaccine production. Hence, there are possibilities for the industry to overcome challenges and enhance patient results in the coming years. This can be achieved by recognizing the intricate nature of clinical issues and continuously working toward surpassing existing limitations.

XBB.1.5 monovalent booster improves antibody binding and neutralization against emerging SARS-CoV-2 Omicron variants

The rapid emergence of divergent SARS-CoV-2 variants has led to an update of the COVID-19 booster vaccine to a monovalent version containing the XBB.1.5 spike. To determine the neutralization breadth following booster immunization, we collected blood samples from 24 individuals pre- and post-XBB.1.5 mRNA booster vaccination (∼1 month). The XBB.1.5 booster improved both neutralizing activity against the ancestral SARS-CoV-2 strain (WA1) and the circulating Omicron variants, including EG.5.1, HK.3, HV.1, XBB.1.5 and JN.1. Relative to the pre-boost titers, the XBB.1.5 monovalent booster induced greater total IgG and IgG subclass binding, particular IgG4, to the XBB.1.5 spike as compared to the WA1 spike. We evaluated antigen-specific memory B cells (MBCs) using either spike or receptor binding domain (RBD) probes and found that the monovalent booster largely increases non-RBD cross-reactive MBCs. These data suggest that the XBB.1.5 monovalent booster induces cross-reactive antibodies that neutralize XBB.1.5 and related Omicron variants.

The Anti-SARS-CoV-2 IgG1 and IgG3 Antibody Isotypes with Limited Neutralizing Capacity against Omicron Elicited in a Latin Population a Switch toward IgG4 after Multiple Doses with the mRNA Pfizer-BioNTech Vaccine

The aim of this study was to analyze the profiles of IgG subclasses in COVID-19 convalescent Puerto Rican subjects and compare these profiles with those of non-infected immunocompetent or immunocompromised subjects that received two or more doses of an mRNA vaccine. The most notable findings from this study are as follows: (1) Convalescent subjects that were not hospitalized developed high and long-lasting antibody responses. (2) Both IgG1 and IgG3 subclasses were more prevalent in the SARS-CoV-2-infected population, whereas IgG1 was more prevalent after vaccination. (3) Individuals that were infected and then later received two doses of an mRNA vaccine exhibited a more robust neutralizing capacity against Omicron than those that were never infected and received two doses of an mRNA vaccine. (4) A class switch toward the "anti-inflammatory" antibody isotype IgG4 was induced a few weeks after the third dose, which peaked abruptly and remained at high levels for a long period. Moreover, the high levels of IgG4 were concurrent with high neutralizing percentages against various VOCs including Omicron. (5) Subjects with IBD also produced IgG4 antibodies after the third dose, although these antibody levels had a limited effect on the neutralizing capacity. Knowing that the mRNA vaccines do not prevent infections, the Omicron subvariants have been shown to be less pathogenic, and IgG4 levels have been associated with immunotolerance and numerous negative effects, the recommendations for the successive administration of booster vaccinations to people should be revised.

Do vaccines increase or decrease susceptibility to diseases other than those they protect against?

Contrary to the long-held belief that the effects of vaccines are specific for the disease they were created; compelling evidence has demonstrated that vaccines can exert positive or deleterious non-specific effects (NSEs). In this review, we compiled research reports from the last 40 years, which were found based on the PubMed search for the epidemiological and immunological studies on the non-specific effects (NSEs) of the most common human vaccines. Analysis of information showed that live vaccines induce positive NSEs, whereas non-live vaccines induce several negative NSEs, including increased female mortality associated with enhanced susceptibility to other infectious diseases, especially in developing countries. These negative NSEs are determined by the vaccination sequence, the antigen concentration in vaccines, the type of vaccine used (live vs. non-live), and also by repeated vaccination. We do not recommend stopping using non-live vaccines, as they have demonstrated to protect against their target disease, so the suggestion is that their detrimental NSEs can be minimized simply by changing the current vaccination sequence. High IgG4 antibody levels generated in response to repeated inoculation with mRNA COVID-19 vaccines could be associated with a higher mortality rate from unrelated diseases and infections by suppressing the immune system. Since most COVID-19 vaccinated countries are reporting high percentages of excess mortality not directly attributable to deaths from such disease, the NSEs of mRNA vaccines on overall mortality should be studied in depth.

Understanding the Interplay of CAR-NK Cells and Triple-Negative Breast Cancer: Insights from Computational Modeling

Chimeric antigen receptor (CAR)-engineered natural killer (NK) cells have recently emerged as a promising and safe alternative to CAR-T cells for targeting solid tumors. In the case of triple-negative breast cancer (TNBC), traditional cancer treatments and common immunotherapies have shown limited effectiveness. However, CAR-NK cells have been successfully employed to target epidermal growth factor receptor (EGFR) on TNBC cells, thereby enhancing the efficacy of immunotherapy. The effectiveness of CAR-NK-based immunotherapy is influenced by various factors, including the vaccination dose, vaccination pattern, and tumor immunosuppressive factors in the microenvironment. To gain insights into the dynamics and effects of CAR-NK-based immunotherapy, we propose a computational model based on experimental data and immunological theories. This model integrates an individual-based model that describes the interplay between the tumor and the immune system, along with an ordinary differential equation model that captures the variation of inflammatory cytokines. Computational results obtained from the proposed model shed light on the conditions necessary for initiating an effective anti-tumor response. Furthermore, global sensitivity analysis highlights the issue of low persistence of CAR-NK cells in vivo, which poses a significant challenge for the successful clinical application of these cells. Leveraging the model, we identify the optimal vaccination time, vaccination dose, and time interval between injections for maximizing therapeutic outcomes.

The durability of vaccine-induced protection: an overview

INTRODUCTION

Current vaccines vary widely in both their efficacy against infection and disease, and the durability of the efficacy. Some vaccines provide practically lifelong protection with a single dose, while others provide only limited protection following annual boosters. What variables make vaccine-induced immune responses last? Can breakthroughs in these factors and technologies help us produce vaccines with better protection and fewer doses? The durability of vaccine-induced protection is now a hot area in vaccinology research, especially after COVID-19 vaccines lost their luster. It has fueled discussion on the eventual utility of existing vaccines to society and bolstered the anti-vaxxer camp. To sustain public trust in vaccines, lasting vaccines must be developed.

AREAS COVERED

This review summarizes licensed vaccines' protection. It analyses immunological principles and vaccine and vaccinee parameters that determine longevity of antibodies. The review concludes with challenges and the way forward to improve vaccine durability.

EXPERT OPINION

Despite enormous advances, we still lack essential markers and reliable correlates of lasting protection. Most research has focused on humoral immune responses, but we must also focus on innate, mucosal, and cellular responses - their assessment, correlates, determinants, and novel adjuvants. Suitable vaccine designs and platforms for durable immunity must be found.

Therapeutic cancer vaccines: advancements, challenges, and prospects

With the development and regulatory approval of immune checkpoint inhibitors and adoptive cell therapies, cancer immunotherapy has undergone a profound transformation over the past decades. Recently, therapeutic cancer vaccines have shown promise by eliciting de novo T cell responses targeting tumor antigens, including tumor-associated antigens and tumor-specific antigens. The objective was to amplify and diversify the intrinsic repertoire of tumor-specific T cells. However, the complete realization of these capabilities remains an ongoing pursuit. Therefore, we provide an overview of the current landscape of cancer vaccines in this review. The range of antigen selection, antigen delivery systems development the strategic nuances underlying effective antigen presentation have pioneered cancer vaccine design. Furthermore, this review addresses the current status of clinical trials and discusses their strategies, focusing on tumor-specific immunogenicity and anti-tumor efficacy assessment. However, current clinical attempts toward developing cancer vaccines have not yielded breakthrough clinical outcomes due to significant challenges, including tumor immune microenvironment suppression, optimal candidate identification, immune response evaluation, and vaccine manufacturing acceleration. Therefore, the field is poised to overcome hurdles and improve patient outcomes in the future by acknowledging these clinical complexities and persistently striving to surmount inherent constraints.

Administration of a glypican-3 peptide increases the infiltration and cytotoxicity of CD8+ T cells against testicular yolk sac tumor, associated with enhancing the intratumoral cGAS/STING signaling

BACKGROUND

Glypican-3 (GPC3) is highly expressed in testicular yolk sac tumor (TYST). GPC3 has been evaluated as a cancer vaccine for some types of tumors, but little is known on the effects of GPC3 peptide-based therapy on TYST. Here, we evaluated the antitumor effect of GPC3144-152 on TYST and its potential mechanisms.

METHODS

GPC3144-152 -specific CD8+ T cells were induced by vaccine immunization and examined by ELISPOT. The CD8+ T cells were purified for testing their cytotoxicity in vitro against TYST cells by CCK-8 and TUNEL assays and in vivo against tumor growth. The influence of GPC3144-152 loading and/or cGAS silencing on the tumor growth, apoptosis and cGAS/STING signaling was tested by immunohistochemistry, immunofluorescence, flow cytometry, and Western blot.

RESULTS

Vaccination with GPC3144-152 induced tumor-specific CD8+ T cells that secreted high levels of IFN-γ and granzyme B, and had potent cytotoxicity against TYST in a dose-dependent manner. Adoptive transfer of CD8+ T cells and treatment with GPC3144-152 significantly inhibited the growth of TYST tumors, but less effective for cGAS-silenced TYST tumors in vivo. Treatment with GPC3144-152 enhanced the infiltration of CD8+ T cells into the tumor environment and their cytotoxicity against TYST tumors in vivo by up-regulating granzyme B and IFN-β expression, but down-regulating GPC3 expression in the tumors. Co-culture of CD8+ T cells with TYST in the presence of exogenous GPC3144-152 enhanced peptide-specific CD8+ T-cell cytotoxicity in vitro, accompanied by enhancing cGAS, γH2AX, TBK1, and IRF3 phosphorylation in TYST cells, but less effective in cGAS-silenced TYST cells.

CONCLUSIONS

These data indicated that GPC3 peptide-specific CD8+ T cells had potent antitumor activity against TYST tumor, particularly for combined treatment with the peptide, which was partially dependent on the intratumoral cGAS/STNG signaling. GPC3 peptide vaccine may be valuable for the combination treatment of TYST.

The effect of dosage on the protective efficacy of whole-sporozoite formulations for immunization against malaria

Immunization with Plasmodium sporozoites, either attenuated or administered under the cover of an antimalarial drug, can induce strong protection against malaria in pre-clinical murine models, as well as in human trials. Previous studies have suggested that whole-sporozoite (WSpz) formulations based on parasites with longer liver stage development induce higher protection, but a comparative analysis of four different WSpz formulations has not been reported. We employed a rodent model of malaria to analyze the effect of immunization dosage on the protective efficacy of WSpz formulations consisting of (i) early liver arresting genetically attenuated parasites (EA-GAP) or (ii) radiation-attenuated sporozoites (RAS), (iii) late arresting GAP (LA-GAP), and (iv) sporozoites administered under chemoprophylaxis, that are eliminated upon release into the bloodstream (CPS). Our results show that, unlike all other WSpz formulations, EA-GAP fails to confer complete protection against an infectious challenge at any immunization dosage employed, suggesting that a minimum threshold of liver development is required to elicit fully effective immune responses. Moreover, while immunization with RAS, LA-GAP and CPS WSpz yields comparable, dosage-dependent protection, protection by EA-GAP WSpz peaks at an intermediate dosage and markedly decreases thereafter. In-depth immunological analyses suggest that effector CD8+ T cells elicited by EA-GAP WSpz immunization have limited developmental plasticity, with a potential negative impact on the functional versatility of memory cells and, thus, on protective immunity. Our findings point towards dismissing EA-GAP from prioritization for WSpz malaria vaccination and enhance our understanding of the complexity of the protection elicited by these WSpz vaccine candidates, guiding their future optimization.

A self-amplifying RNA vaccine provides protection in a murine model of bubonic plague

Mice were immunized with a combination of self-amplifying (sa) RNA constructs for the F1 and V antigens of Yersinia pestis at a dose level of 1 μg or 5 μg or with the respective protein sub-units as a reference vaccine. The immunization of outbred OF1 mice on day 0 and day 28 with the lowest dose used (1 μg) of each of the saRNA constructs in lipid nanoparticles protected 5/7 mice against subsequent sub-cutaneous challenge on day 56 with 180 cfu (2.8 MLD) of a 2021 clinical isolate of Y. pestis termed 10-21/S whilst 5/7 mice were protected against 1800cfu (28MLD) of the same bacteria on day 56. By comparison, only 1/8 or 1/7 negative control mice immunized with 10 μg of irrelevant haemagglutin RNA in lipid nanoparticles (LNP) survived the challenge with 2.8 MLD or 28 MLD Y. pestis 10-21/S, respectively. BALB/c mice were also immunized with the same saRNA constructs and responded with the secretion of specific IgG to F1 and V, neutralizing antibodies for the V antigen and developed a recall response to both F1 and V. These data represent the first report of an RNA vaccine approach using self-amplifying technology and encoding both of the essential virulence antigens, providing efficacy against Y. pestis. This saRNA vaccine for plague has the potential for further development, particularly since its amplifying nature can induce immunity with less boosting. It is also amenable to rapid manufacture with simpler downstream processing than protein sub-units, enabling rapid deployment and surge manufacture during disease outbreaks.

Antibody response to 1.0 and 0.5 mL doses of an inactivated bacterial vaccine against bovine respiratory disease in young Holstein calves: a field trial

Introduction

Early vaccination of cattle with an inactivated commercial bacterial vaccine against bovine respiratory disease has been reported to increase antibody production and can alleviate the disease. However, its dosage has been little investigated in young Holstein calves. This study addresses the need to establish guide values for vaccine dosage in these animals.

Material and Methods

Healthy calves received an inactivated vaccine for Histophilus somni, Pasteurella multocida and Mannheimia haemolytica intramuscularly at the ages of 1 and 4 weeks. Administered vaccine doses were 1.0 mL for the primary and booster vaccinations (1.0 + 1.0 group), 0.5 mL for the primary and 1.0 mL for the booster vaccination (0.5 + 1.0 group), or 0.5 mL for both vaccinations (0.5 + 0.5 group).

Results

Differences in the vaccine responses between the 1.0 + 1.0 group and 0.5 + 1.0 group were minor. However, the number of calves with a positive vaccine response to H. somni in the 0.5 + 0.5 group was less than half of that in the 1.0 + 1.0 and 0.5 + 1.0 groups. In logistic regression analysis, although the booster vaccination dose was positively correlated with seropositivity for H. somni, the primary vaccination dose was not correlated with vaccine response. The number of calves with positive vaccine responses to M. haemolytica was low even after booster vaccination regardless of the dose.

Conclusion

The dose of 0.5 mL can be used for primary vaccinations in newborn Holstein calves, but 1.0 mL may be required for booster vaccinations.

Tissue-resident memory T cells mediate mucosal immunity to recurrent urinary tract infection

Urinary tract infection (UTI) is one of the most prevalent human bacterial infections. New therapeutic approaches, including vaccination and immunotherapy, are urgently needed to combat the rapid global dissemination of multidrug-resistant uropathogens. Development of therapies is impeded by an incomplete understanding of memory development during UTI. Here, we found that reducing bacterial load early in infection, by reducing the inoculum or with antibiotics after infection, completely abrogated the protective memory response. We observed a mixed T helper (T_H) cell polarization, composed of T_H1, T_H2, and T_H17 T cells, among T cells infiltrating the bladder during primary infection. Thus, we hypothesized that reducing antigen load altered T_H cell polarization, leading to poor memory. Unexpectedly, however, T_H cell polarization was unchanged in these scenarios. Instead, we uncovered a population of tissue-resident memory (T_RM) T cells that was significantly reduced in the absence of sufficient antigen. Demonstrating that T_RM cells are necessary for immune memory, transfer of lymph node- or spleen-derived infection-experienced T cells to naïve animals did not confer protection against infection. Supporting that T_RM cells are sufficient to protect against recurrent UTI, animals depleted of systemic T cells, or treated with FTY720 to block memory lymphocyte migration from lymph nodes to infected tissue, were equally protected compared with unmanipulated mice against a second UTI. Thus, we uncovered an unappreciated key role for T_RM cells in the memory response to bacterial infection in the bladder mucosa, providing a target for non-antibiotic-based immunotherapy and/or new vaccine strategies to prevent recurrent UTI.

IgG4 Antibodies Induced by Repeated Vaccination May Generate Immune Tolerance to the SARS-CoV-2 Spike Protein

Less than a year after the global emergence of the coronavirus SARS-CoV-2, a novel vaccine platform based on mRNA technology was introduced to the market. Globally, around 13.38 billion COVID-19 vaccine doses of diverse platforms have been administered. To date, 72.3% of the total population has been injected at least once with a COVID-19 vaccine. As the immunity provided by these vaccines rapidly wanes, their ability to prevent hospitalization and severe disease in individuals with comorbidities has recently been questioned, and increasing evidence has shown that, as with many other vaccines, they do not produce sterilizing immunity, allowing people to suffer frequent re-infections. Additionally, recent investigations have found abnormally high levels of IgG4 in people who were administered two or more injections of the mRNA vaccines. HIV, Malaria, and Pertussis vaccines have also been reported to induce higher-than-normal IgG4 synthesis. Overall, there are three critical factors determining the class switch to IgG4 antibodies: excessive antigen concentration, repeated vaccination, and the type of vaccine used. It has been suggested that an increase in IgG4 levels could have a protecting role by preventing immune over-activation, similar to that occurring during successful allergen-specific immunotherapy by inhibiting IgE-induced effects. However, emerging evidence suggests that the reported increase in IgG4 levels detected after repeated vaccination with the mRNA vaccines may not be a protective mechanism; rather, it constitutes an immune tolerance mechanism to the spike protein that could promote unopposed SARS-CoV2 infection and replication by suppressing natural antiviral responses. Increased IgG4 synthesis due to repeated mRNA vaccination with high antigen concentrations may also cause autoimmune diseases, and promote cancer growth and autoimmune myocarditis in susceptible individuals.

Human memory T cell dynamics after aluminum-adjuvanted inactivated whole-virion SARS-CoV-2 vaccination

This study evaluates the functional capacity of CD4+ and CD8+ terminally-differentiated effector (TEMRA), central memory (TCM), and effector memory (TEM) cells obtained from the volunteers vaccinated with an aluminum-adjuvanted inactivated whole-virion SARS-CoV-2 vaccine (CoronaVac). The volunteers were followed for T cell immune responses following the termination of a randomized phase III clinical trial. Seven days and four months after the second dose of the vaccine, the memory T cell subsets were collected and stimulated by autologous monocyte-derived dendritic cells (mDCs) loaded with SARS-CoV-2 spike glycoprotein S1. Compared to the placebo group, memory T cells from the vaccinated individuals significantly proliferated in response to S1-loaded mDCs. CD4+ and CD8+ memory T cell proliferation was detected in 86% and 78% of the vaccinated individuals, respectively. More than 73% (after a short-term) and 62% (after an intermediate-term) of the vaccinated individuals harbored TCM and/or TEM cells that responded to S1-loaded mDCs by secreting IFN-γ. The expression of CD25, CD38, 4-1BB, PD-1, and CD107a indicated a modulation in the memory T cell subsets. Especially on day 120, PD-1 was upregulated on CD4+ TEMRA and TCM, and on CD8+ TEM and TCM cells; accordingly, proliferation and IFN-γ secretion capacities tended to decline after 4 months. In conclusion, the combination of inactivated whole-virion particles with aluminum adjuvants possesses capacities to induce functional T cell responses.

Influence of Humoral Response Against GnRH, Generated by Immunization with a Therapeutic Vaccine Candidate on the Evolution of Patients with Castration-Sensitive Prostate Adenocarcinoma

BACKGROUND AND AIMS

A gonadotropin-releasing hormone (GnRH)-based therapeutic vaccine candidate against hormone-sensitive prostate cancer has demonstrated its safety and signs of efficacy in phase I/II trials. In this study, we characterized the isotype/subclass profiles of the anti-GnRH humoral response generated by the vaccination and analyzed its association with patients' clinical outcomes.

METHODS

The immunoglobulin isotypes and IgG subclasses of the antibody responses of 34 patients included in a randomized, open, prospective phase I/II clinical trial were characterized. Every patient included in the study had a diagnosis of locally advanced prostate adenocarcinoma at stages 3 and 4 and received immunization with the vaccine candidate. Additionally, serum testosterone and prostate specific antigen (PSA) concentrations, serving as indicators of tumor response, were determined. The type of anti-GnRH antibody response was correlated to the time elapsed until the first biochemical recurrence in patients and the outcome of the disease.

RESULTS

All patients developed strong and prolonged anti-GnRH antibody responses, resulting in a short- to mid-term decrease in serum testosterone and PSA levels. Following immunizations, anti-GnRH antibodies of the IgM/IgG and IgG1/IgG3 subclasses were observed. Following radiotherapy, the humoral response switched to IgG (IgG1/IgG4). Patients who experienced a short-term biochemical relapse were characterized by significantly higher levels of anti-GnRH IgG titers, particularly IgG1 and IgG4 subclasses. These characteristics, along with a high response of specific IgM antibodies at the end of immunizations and the development of anti-GnRH IgA antibody responses following radiotherapy, were observed in patients whose disease progressed, compared to those with controlled disease.

CONCLUSION

The nature of the humoral response against anti-GnRH, induced by vaccination may play a key role in activating additional immunological mechanisms. Collectively, these mechanisms could contribute significantly to the regulation of tumor growth.

Potential Immunologic and Integrative Methods to Enhance Vaccine Safety

Vaccine safety is measured by the disease protection it confers compared to the harm it may cause; both factors and their relative numbers have been the subject of disagreement. Cross-reactive attack of analogous self-antigens modified by dietary and microbiome factors is one of the poorly explored likely causes of harm. Screening for that and other risk factors might point out those most likely to develop severe vaccine reactions. Cooperation from those with opinions for and against vaccination in data gathering and vetting will lead to greater safety. Screening should include an integrative medical perspective regarding diet, microbiome, leaky gut, and other antigen sources. It might include emerging electronic technology or integrative energetic techniques vetted ultimately by cross-reactive lymphocyte testing or genetic evaluation. The knowledge gained from evaluating those with reactions could enhance the screening process and, since similar antigenic stimuli and reactions are involved, help long COVID sufferers. Centers for early identification and rescue from vaccine reactions could lower morbidity and mortality, and increase the percentage of people choosing to be vaccinated. Additional platforms for boosting; using lower dosage; other routes of administration, such as intranasal or intradermal needles; and possibly different antigens could make it easier to vaccinate globally to address the new variants of viruses rapidly arising.

Nanoparticle-delivered TLR4 and RIG-I agonists enhance immune response to SARS-CoV-2 subunit vaccine

Despite success in vaccinating populations against SARS-CoV-2, concerns about immunity duration, continued efficacy against emerging variants, protection from infection and transmission, and worldwide vaccine availability remain. Molecular adjuvants targeting pattern recognition receptors (PRRs) on antigen-presenting cells (APCs) could improve and broaden the efficacy and durability of vaccine responses. Native SARS-CoV-2 infection stimulates various PRRs, including toll-like receptors (TLRs) and retinoic acid-inducible gene I (RIG-I)-like receptors. We hypothesized that targeting PRRs using molecular adjuvants on nanoparticles (NPs) along with a stabilized spike protein antigen could stimulate broad and efficient immune responses. Adjuvants targeting TLR4 (MPLA), TLR7/8 (R848), TLR9 (CpG), and RIG-I (PUUC) delivered on degradable polymer NPs were combined with the S1 subunit of spike protein and assessed in vitro with isogeneic mixed lymphocyte reactions (isoMLRs). For in vivo studies, the adjuvant-NPs were combined with stabilized spike protein or spike-conjugated NPs and assessed using a two-dose intranasal or intramuscular vaccination model in mice. Combination adjuvant-NPs simultaneously targeting TLR and RIG-I receptors (MPLA+PUUC, CpG+PUUC, and R848+PUUC) differentially induced T cell proliferation and increased proinflammatory cytokine secretion by APCs in vitro. When delivered intranasally, MPLA+PUUC NPs enhanced CD4+CD44+ activated memory T cell responses against spike protein in the lungs while MPLA NPs increased anti-spike IgA in the bronchoalveolar (BAL) fluid and IgG in the blood. Following intramuscular delivery, PUUC NPs induced strong humoral immune responses, characterized by increases in anti-spike IgG in the blood and germinal center B cell populations (GL7+ and BCL6+ B cells) in the draining lymph nodes (dLNs). MPLA+PUUC NPs further boosted spike protein-neutralizing antibody titers and T follicular helper cell populations in the dLNs. These results suggest that protein subunit vaccines with particle-delivered molecular adjuvants targeting TLR4 and RIG-I could lead to robust and unique route-specific adaptive immune responses against SARS-CoV-2.

Changing Landscape of Cancer Vaccines-Novel Proteomics Platform for New Antigen Compositions

The creation of cancer vaccines is a constant priority for research and biotechnology. Therefore, the emergence of any new technology in this field is a significant event, especially because previous technologies have not yielded results. Recently, the development of a cancer vaccine has been complemented by a new proteomics technology platform that allows the creation of antigen compositions known as antigenic essences. Antigenic essence comprises a target fraction of cellular antigens, the composition of which is precisely controlled by peptide mass spectrometry and compared to the proteomic footprint of the target cells to ensure similarity. This proteomics platform offers potential for a massive upgrade of conventional cellular cancer vaccines. Antigenic essences have the same mechanism of action, but without the disadvantages, and with notable advantages such as precise targeting of the immune response, safety, controlled composition, improved immunogenicity, addressed MHC restriction, and extended range of vaccination doses. The present paper calls attention to this novel platform, stimulates discussion of the role of antigenic essence in vaccine development, and consolidates academic science with biotech capabilities. A brief description of the platform, list of cellular cancer vaccines suitable for the upgrade, main recommendations, limitations, and legal and ethical aspects of vaccine upgrade are reported here.

Nanoparticle-delivered TLR4 and RIG-I agonists enhance immune response to SARS-CoV-2 subunit vaccine

Despite recent success in vaccinating populations against SARS-CoV-2, concerns about immunity duration, continued efficacy against emerging variants, protection from infection and transmission, and worldwide vaccine availability, remain. Although mRNA, pDNA, and viral-vector based vaccines are being administered, no protein subunit-based SARS-CoV-2 vaccine is approved. Molecular adjuvants targeting pathogen-recognition receptors (PRRs) on antigen-presenting cells (APCs) could improve and broaden the efficacy and durability of vaccine responses. Native SARS-CoV-2 infection stimulate various PRRs, including toll-like receptors (TLRs) and retinoic-acid-inducible gene I-like receptors (RIG-I). We hypothesized that targeting the same PRRs using adjuvants on nanoparticles along with a stabilized spike (S) protein antigen could provide broad and efficient immune responses. Formulations targeting TLR4 (MPLA), TLR7/8 (R848), TLR9 (CpG), and RIG-I (PUUC) delivered on degradable polymer-nanoparticles (NPs) were combined with the S1 subunit of S protein and assessed in vitro with isogeneic mixed lymphocyte reactions (iso-MLRs). For in vivo studies, the adjuvanted nanoparticles were combined with stabilized S protein and assessed using intranasal and intramuscular prime-boost vaccination models in mice. Combination NP-adjuvants targeting both TLR and RIG-I (MPLA+PUUC, CpG+PUUC, or R848+PUUC) differentially increased proinflammatory cytokine secretion (IL-1β, IL-12p70, IL-27, IFN-β) by APCs cultured in vitro, and induced differential T cell proliferation. When delivered intranasally, MPLA+PUUC NPs enhanced local CD4+CD44+ activated memory T cell responses while MPLA NPs increased anti-S-protein-specific IgG and IgA in the lung. Following intramuscular delivery, PUUC-carrying NPs induced strong humoral immune responses, characterized by increases in anti-S-protein IgG and neutralizing antibody titers and germinal center B cell populations (GL7+ and BCL6+ B cells). MPLA+PUUC NPs further boosted S-protein-neutralizing antibody titers and T follicular helper cell populations in draining lymph nodes. These results suggest that SARS-CoV-2-mimicking adjuvants and subunit vaccines could lead to robust and unique route-specific adaptive immune responses and may provide additional tools against the pandemic.

Nanocell COVID-19 vaccine triggers a novel immune response pathway producing high-affinity antibodies which neutralize all variants of concern

Most current anti-viral vaccines elicit a humoral and cellular immune response via the pathway of phagocytic cell mediated viral antigen presentation to B and T cell surface receptors. However, this pathway results in reduced ability to neutralize S-protein Receptor Binding Domains (RBDs) from several Variants of Concern (VOC) and the rapid waning of memory B cell response requiring vaccine reformulation to cover dominant VOC S-proteins and multiple boosters. Here we show for the first time in mice and humans, that a bacterially derived, non-living, nanocell (EDV; EnGeneIC Dream Vector) packaged with plasmid expressed SARS-CoV-2 S-protein and α-galactosyl ceramide adjuvant (EDV-COVID-αGC), stimulates an alternate pathway due to dendritic cells (DC) displaying both S-polypeptides and αGC thereby recruiting and activating iNKT cells with release of IFNγ. This triggers DC activation/maturation, activation of follicular helper T cells (T_FH), cognate help to B cells with secretion of a cytokine milieu promoting B cell maturation, somatic hypermutation in germinal centers to result in high affinity antibodies. Surrogate virus neutralization tests show 90-100% neutralization of ancestral and early VOC in mice and human trial volunteers. EDV-COVID-αGC as a third dose booster neutralized Omicron BA. 4/5. Serum and PBMC analyses reveal long lasting S-specific memory B and T cells. In contrast, control EDVs lacking αGC, did not engage the iNKT/DC pathway resulting in antibody responses unable to neutralize all VOCs and had a reduced B cell memory. The vaccine is lyophilized, stored and transported at room temperature with a shelf-life of over a year.

Combinatorial in silico and in vivo evaluation of immune response elicitation by the affibody ZHER2

Due to the high affinity for binding to target molecules and also other unique attributes, affibodies have a great potential to be used in immunotherapeutic and diagnostic approaches. However, the possibility of undesirable immune response is still a great concern. In the current study, we investigated the possible antigenicity, allergenicity and cytotoxicity of the HER2-targeting affibody Z_HER2. The binding affinity of potential epitopes of the affibody to murine major histocompatibility complex (MHC) molecules was investigated by immunoinformatics tools and docking approaches. The possible interaction of Z_HER2 with human leukocyte antigens HLA-DP, HLA-DM, HLA-DQ and HLA-DR was also studied by protein-protein docking. Additionally, the synthesized affibody gene was expressed and the protein was purified for boosted immunization of Balb/c mice. Induced secretion of IFN-γ, IL-2, IL-4 and IL-10, and total serum IgG were assessed in the immunized mice. Furthermore, MTT cell viability test was performed to evaluate the cytotoxicity of Z_HER2 in splenocytes of the treated mice. In silico analyses showed the possible induction of the immune response by Z_HER2. While the affibody could elicit the secretion of cellular immune cytokines, it could not induce a significant humoral response in the treated mice and did not show any cytotoxic effects on the exposed splenocytes. These findings explain the practicability of Z_HER2 for therapeutic and in vivo diagnostic usages, though its ubiquitous application may need more studies.

Review: Development of SARS-CoV-2 immuno-enhanced COVID-19 vaccines with nano-platform

Vaccination is the most effective way to prevent coronavirus disease 2019 (COVID-19). Vaccine development approaches consist of viral vector vaccines, DNA vaccine, RNA vaccine, live attenuated virus, and recombinant proteins, which elicit a specific immune response. The use of nanoparticles displaying antigen is one of the alternative approaches to conventional vaccines. This is due to the fact that nano-based vaccines are stable, able to target, form images, and offer an opportunity to enhance the immune responses. The diameters of ultrafine nanoparticles are in the range of 1-100 nm. The application of nanotechnology on vaccine design provides precise fabrication of nanomaterials with desirable properties and ability to eliminate undesirable features. To be successful, nanomaterials must be uptaken into the cell, especially into the target and able to modulate cellular functions at the subcellular levels. The advantages of nano-based vaccines are the ability to protect a cargo such as RNA, DNA, protein, or synthesis substance and have enhanced stability in a broad range of pH, ambient temperatures, and humidity for long-term storage. Moreover, nano-based vaccines can be engineered to overcome biological barriers such as nonspecific distribution in order to elicit functions in antigen presenting cells. In this review, we will summarize on the developing COVID-19 vaccine strategies and how the nanotechnology can enhance antigen presentation and strong immunogenicity using advanced technology in nanocarrier to deliver antigens. The discussion about their safe, effective, and affordable vaccines to immunize against COVID-19 will be highlighted.

Coxiella burnetii Whole Cell Vaccine Produces a Th1 Delayed-Type Hypersensitivity Response in a Novel Sensitized Mouse Model

Q-VAX®, a whole cell, formalin-inactivated vaccine, is the only vaccine licensed for human use to protect against Coxiella burnetii, the cause of Q fever. Although this vaccine provides long-term protection, local and systemic reactogenic responses are common in previously sensitized individuals which prevents its use outside of Australia. Despite the importance of preventing these adverse reactions to develop widely accepted, novel vaccines against C. burnetii, little is understood about the underlying cellular mechanisms. This is mostly attributed to the use of a guinea pig reactogenicity model where complex cellular analysis is limited. To address this, we compared three different mouse strains develop a model of C. burnetii whole cell vaccine reactogenic responses. SKH1 and C57Bl/6, but not BALBc mice, develop local granulomatous reactions after either infection- or vaccine-induced sensitization. We evaluated local and systemic responses by measuring T cell populations from the vaccination site and spleen during elicitation using flow cytometry. Local reaction sites showed influx of IFNγ+ and IL17a+ CD4 T cells in sensitized mice compared with controls and a reduction in IL4+ CD4 T cells. Additionally, sensitized mice showed a systemic response to elicitation by an increase in IFNγ+ and IL17a+ CD4 T cells in the spleen. These results indicate that local and systemic C. burnetii reactogenic responses are consistent with a Th1 delayed-type hypersensitivity. Our experiments provide insights into the pathophysiology of C. burnetii whole cell vaccine reactogenicity and demonstrate that C57Bl/6 and SKH1 mice can provide a valuable model for evaluating the reactogenicity of novel C. burnetii vaccine candidates.

IMRAS-Immunization with radiation-attenuated Plasmodium falciparum sporozoites by mosquito bite: Cellular immunity to sporozoites, CSP, AMA1, TRAP and CelTOS

BACKGROUND

Immunization with radiation-attenuated sporozoites (RAS) by mosquito bites provides >90% sterile protection against Plasmodium falciparum malaria in humans. We conducted a clinical trial based on data from previous RAS clinical trials that suggested that 800-1200 infected bites should induce ~50% protective vaccine efficacy (VE) against controlled human malaria infection (CHMI) administered three weeks after the final immunization. Two cohorts were immunized separately. VE was 55% in Cohort 1 but 90% in Cohort 2, the cohort that received a higher first dose and a reduced (fractional) fifth dose. Immune responses were better boosted by the fractional fifth dose in Cohort 2 and suggested the importance of the fractional fifth dose for increased protection in Cohort 2 responses. Three protected subjects were later boosted and were protected suggesting that protection could be extended to at least 67 weeks.

METHODS

The ex vivo FluoroSpot assay was used to measure peripheral IFN-γ, IL2, and IFN-γ+IL2 responses to PfNF54 sporozoites and malaria antigens CSP, AMA1, TRAP, and CelTOS using pools of synthetic overlapping 15mer peptides spanning each antigen.

RESULTS

There was no correlation between IFN-γ, IL2, and IFN-γ+IL2 responses to sporozoites and protection, but fold-increases between post-4th and post-5th responses greater than 1.0 occurred mostly in protected subjects. IFN-γ and IL2 responses to TRAP, CelTOS and CSP occurred only in protected subjects. Peripheral IFN-γ, IL2, and IFN-γ+IL2 responses were short-lived and low by 27 weeks post-CHMI but were restored by boosting.

CONCLUSIONS

These studies highlight the importance of vaccine dose and schedule for vaccine efficacy, and suggest that CSP, TRAP, AMA1 and CelTOS may be targets of protective immunity. The correlation between fold-increases in responses and protection should be explored in other vaccine trials.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01994525.

Oral Vaccination Approaches for Anti-SHIV Immunity

We modified a Sabin Oral Poliovirus Vaccine (OPV) vector to permit secretion of the antigens of interest with the goal of improving anti-HIV Env humoral responses in a SHIV mucosal immunization composed of DNA and recombinant OPVs. We evaluated stimulation of systemic and mucosal cell-mediated and humoral immunity in Rhesus macaques by two regimens, both involving a prime with a SHIVBG505 DNA construct producing non-infectious particles formulated in lipid nanoparticles, administered in the oral cavity, and two different viral vector boostings, administered in the oral cavity and intestinally. Group 1 was boosted with rMVA-SHIVBG505, expressing SIV Gag/Pol and HIVBG505 Env. Group 2 was boosted with a SHIVBG505-OPV vaccine including a non-secreting SIVmac239CA-p6-OPV, expressing Gag CA, NC and p6 proteins, and a HIVBG505C1-V2-OPV, secreting the C1-V2 fragment of HIV EnvBG505, recognized by the broadly neutralizing antibody PG16. A time course analysis of anti-SHIV Gag and Env CD4+ and CD8+ T-cell responses in PBMC and in lymph node, rectal, and vaginal MNC was carried out. Both regimens stimulated significant cell-mediated responses in all compartments, with SHIVBG505-OPV immunization stimulating more significant levels of responses than rMVA- SHIVBG505. Boolean analysis of these responses revealed predominantly monofunctional responses with multifunctional responses also present in all tissues. Stimulation of antibody responses was disappointing in both groups with negative anti-SHIV IgG in plasma, and IgA in salivary, rectal and vaginal secretions being restricted to a few animals. After repeated rectal challenge with SHIVBG505, two Group 1 animals remained uninfected at challenge termination. No significant differences were observed in post-infection viral loads between groups. After the acute phase decline, CD4+ T cell percentages returned to normal levels in vaccinated as well as control animals. However, when compared to controls, vaccinate groups had more significant preservation of PBMC and rectal MNC Th17/Treg ratios, considered the strongest surrogate marker of progression to AIDS. We conclude that the vaccine platforms used in this study are insufficient to stimulate significant humoral immunity at the tested doses and schedule but sufficient to stimulate significant mucosal and systemic cell-mediated immunity, impacting the preservation of key Th17 CD4+ T cells in blood and rectal mucosa.

Repeated Exposure to Subinfectious Doses of SARS-CoV-2 May Promote T Cell Immunity and Protection against Severe COVID-19

Europe is experiencing a third wave of COVID-19 due to the spread of highly transmissible SARS-CoV-2 variants. A number of positive and negative factors constantly shape the rates of COVID-19 infections, hospitalization, and mortality. Among these factors, the rise in increasingly transmissible variants on one side and the effect of vaccinations on the other side create a picture deeply different from that of the first pandemic wave. Starting from the observation that in several European countries the number of COVID-19 infections in the second and third pandemic wave increased without a proportional rise in disease severity and mortality, we hypothesize the existence of an additional factor influencing SARS-CoV-2 dynamics. This factor consists of an immune defence against severe COVID-19, provided by SARS-CoV-2-specific T cells progressively developing upon natural exposure to low virus doses present in populated environments. As suggested by recent studies, low-dose viral particles entering the respiratory and intestinal tracts may be able to induce T cell memory in the absence of inflammation, potentially resulting in different degrees of immunization. In this scenario, non-pharmaceutical interventions would play a double role, one in the short term by reducing the detrimental spreading of SARS-CoV-2 particles, and one in the long term by allowing the development of a widespread (although heterogeneous and uncontrollable) form of immune protection.

Multiple Levels of Immunological Memory and Their Association with Vaccination

Immunological memory is divided into many levels to counteract the provocations of diverse and ever-changing infections. Fast functions of effector memory and the superposition of both quantitatively and qualitatively plastic anticipatory memory responses together form the walls of protection against pathogens. Here we provide an overview of the role of different B and T cell subsets and their interplay, the parallel and independent functions of the B1, marginal zone B cells, T-independent- and T-dependent B cell responses, as well as functions of central and effector memory T cells, tissue-resident and follicular helper T cells in the memory responses. Age-related limitations in the immunological memory of these cell types in neonates and the elderly are also discussed. We review how certain aspects of immunological memory and the interactions of components can affect the efficacy of vaccines, in order to link our knowledge of immunological memory with the practical application of vaccination.

Development of vaccine formulations: past, present, and future

The current situation, heavily influenced by the ongoing pandemic, puts vaccines back into the spotlight. However, the conventional and traditional vaccines present disadvantages, particularly related to immunogenicity, stability, and storage of the final product. Often, such products require the maintenance of a “cold chain,” impacting the costs, the availability, and the distribution of vaccines. Here, after a recall of the mode of action of vaccines and the types of vaccines currently available, we analyze the past, present, and future of vaccine formulation. The past focuses on conventional formulations, the present discusses the use of nanoparticles for vaccine delivery and as adjuvants, while the future presents microneedle patches as alternative formulation and administration route. Finally, we compare the advantages and disadvantages of injectable solutions, nanovaccines, and microneedles in terms of efficacy, stability, and patient-friendly design.

Different approaches to vaccine formulation development, the conventional vaccine formulations from the past, the current development of lipid nanoparticles as vaccines, and the near future microneedles formulations are discussed in this review. 

Personalized Cancer Vaccines: Clinical Landscape, Challenges, and Opportunities

Tremendous innovation is underway among a rapidly expanding repertoire of promising personalized immune-based treatments. Therapeutic cancer vaccines (TCVs) are attractive systemic immunotherapies that activate and expand antigen-specific CD8⁺ and CD4⁺ T cells to enhance anti-tumor immunity. Our review highlights key issues impacting TCVs in clinical practice and reports on progress in development. We review the mechanism of action, immune-monitoring, dosing strategies, combinations, obstacles, and regulation of cancer vaccines. Most trials of personalized TCVs are ongoing and represent diverse platforms with predominantly early investigations of mRNA, DNA, or peptide-based targeting strategies against neoantigens in solid tumors, with many in combination immunotherapies. Multiple delivery systems, routes of administration, and dosing strategies are used. Intravenous or intramuscular administration is common, including delivery by lipid nanoparticles. Absorption and biodistribution impact antigen uptake, expression, and presentation, affecting the strength, speed, and duration of immune response. The emerging trials illustrate the complexity of developing this class of innovative immunotherapies. Methodical testing of the multiple potential factors influencing immune responses, as well as refined quantitative methodologies to facilitate optimal dosing strategies, could help resolve uncertainty of therapeutic approaches. To increase the likelihood of success in bringing these medicines to patients, several unique development challenges must be overcome.

Cocktail Anti-Tick Vaccines: The Unforeseen Constraints and Approaches toward Enhanced Efficacies

Ticks are second to mosquitoes as vectors of disease. Ticks affect livestock industries in Asia, Africa and Australia at ~$1.13 billion USD per annum. For instance, 80% of the global cattle population is at risk of infestation by the Rhipicephalus microplus species-complex, which in 2016 was estimated to cause $22-30 billion USD annual losses. Although the management of tick populations mainly relies on the application of acaricides, this raises concerns due to tick resistance and accumulation of chemical residues in milk, meat, and the environment. To counteract acaricide-resistant tick populations, immunological tick control is regarded among the most promising sustainable strategies. Indeed, immense efforts have been devoted toward identifying tick vaccine antigens. Until now, Bm86-based vaccines have been the most effective under field conditions, but they have shown mixed success worldwide. Currently, of the two Bm86 vaccines commercialized in the 1990s (GavacTM in Cuba and TickGARDPLUSTM in Australia), only GavacTM is available. There is thus growing consensus that combining antigens could broaden the protection range and enhance the efficacies of tick vaccines. Yet, the anticipated outcomes have not been achieved under field conditions. Therefore, this review demystifies the potential limitations and proposes ways of sustaining enhanced cocktail tick vaccine efficacy.