Nanoparticle Vaccine Research Articles

CLDN6 CAR-T cell therapy of relapsed/refractory solid tumors ± a CLDN6-encoding mRNA vaccine: Dose escalation data from the BNT211-01 phase 1 trial using an automated product.

2518 Background: We are developing a chimeric antigen receptor (CAR)-T cell therapy targeting claudin 6 (CLDN6), an oncofetal antigen that is undetectable in healthy somatic tissue and highly expressed in various solid cancers. Autologous CLDN6 CAR-T cells are being tested alone and in combination with CLDN6-encoding CAR-T cell Amplifying RNA Vaccine (CARVac), a nanoparticulate RNA vaccine designed to stimulate and expand CLDN6 CAR-T cells. Methods: The ongoing first-in-human trial BNT211-01 evaluates the safety and feasibility of CLDN6 CAR-T cell transfer ± CARVac in lymphodepleted patients with relapsed/refractory solid tumors. Patients are pre-screened for CLDN6 expression with a cut-off of 50% positivity of intermediate or strong intensity by immunohistochemistry staining. Key endpoints are safety, tolerability, and anti-tumor activity. Pharmacokinetics of adoptively transferred CAR-T cells in peripheral blood is monitored by quantitative PCR. Dose escalation proceeds according to a classical 3+3 design, testing CLDN6 CAR-T cells at each dose level as both as monotherapy and in combination with CARVac. We previously reported results from 22 patients from 4 dose escalation cohorts with a manual CAR-T production process ± CARVac (ESMO-IO LBA38) which followed the same methodology. We observed durable responses along with a manageable safety profile, in line with commercial CAR-T products used to treat B-cell malignancies. No on-target/off-tumor toxicity and only a single case of (grade 1) neurotoxicity was observed. Given the encouraging efficacy, we have implemented an automated process to scale-up manufacturing. Accordingly, we are repeating the dose escalation with an automated CAR-T cell product, and with a modified CARVac regimen. As of 1st February 2023, 7 patients with epithelial ovarian carcinoma (EOC), 4 with testicular germ cell tumors (GCT), and a further 5 patients with tumors of various indications have been infused with CAR-T cells up to DL2. We intend to submit efficacy, safety and CAR T-cell pharmacokinetics data from 5 cohorts treated with 1x106, 1x107 or 1x108 CLDN6 CAR-T cells ± CARVac with a data cut-off of March 14th, 2023 from ≥17 treated patients as a late-breaking abstract. Clinical trial information: NCT04503278 .

Evaluation of the immunogenicity of a Crimean-Congo hemorrhagic fever virus vaccine candidate in mice developed based on a baculovirus Zera nanoparticle delivery system.

Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic disease caused by Crimean-Congo hemorrhagic fever virus (CCHFV), which can cause severe clinical disease and even death in humans. In recent years, the disease has spread to a wider area, posing a major public health threat to China as well as the Middle East, Europe and Africa, and there is no safe and effective vaccine to prevent the disease. Recently, it has been shown that using the Zera fusion to target proteins can enhance immunogenicity and improve the potential for developing viral vaccines. Based on this finding, in this study, two vaccine candidates, Zera-Gn and Zera-Np, were prepared using an insect baculovirus system expressing CCHFV glycoprotein (Gn) and nucleocapsid protein (Np) fused with Zera tags, and evaluated for immunogenicity in BALB/c mice. The obtainedresults showed that both Zera-Gn and Zera-Np recombinant nanoparticles were successfully expressed, and Zera-Gn had good induction of humoral and cellular immunity in mice, and its immunogenicity was significantly higher than that of Zera-Np. The results indicated that Zera-Gn self-assembled nanoparticles prepared by fusing Zera tags with CCHFV spike-in protein Gn have the potential to be a candidate vaccine for CCHF, and this study provides a reference for the development of Zera self-assembled nanoparticle vaccine for CCHF.

A first-in-human germline-targeting HIV nanoparticle vaccine induced broad and publicly targeted helper T cell responses.

The engineered outer domain germline targeting version 8 (eOD-GT8) 60-mer nanoparticle was designed to prime VRC01-class HIV-specific B cells that would need to be matured, through additional heterologous immunizations, into B cells that are able to produce broadly neutralizing antibodies. CD4 T cell help will be critical for the development of such high-affinity neutralizing antibody responses. Thus, we assessed the induction and epitope specificities of the vaccine-specific T cells from the IAVI G001 phase 1 clinical trial that tested immunization with eOD-GT8 60-mer adjuvanted with AS01B. Robust polyfunctional CD4 T cells specific for eOD-GT8 and the lumazine synthase (LumSyn) component of eOD-GT8 60-mer were induced after two vaccinations with either the 20- or 100-microgram dose. Antigen-specific CD4 T helper responses to eOD-GT8 and LumSyn were observed in 84 and 93% of vaccine recipients, respectively. CD4 helper T cell epitope "hotspots" preferentially targeted across participants were identified within both the eOD-GT8 and LumSyn proteins. CD4 T cell responses specific to one of these three LumSyn epitope hotspots were observed in 85% of vaccine recipients. Last, we found that induction of vaccine-specific peripheral CD4 T cells correlated with expansion of eOD-GT8-specific memory B cells. Our findings demonstrate strong human CD4 T cell responses to an HIV vaccine candidate priming immunogen and identify immunodominant CD4 T cell epitopes that might improve human immune responses either to heterologous boost immunogens after this prime vaccination or to other human vaccine immunogens.

Effective immuno-therapeutic treatment of Canine Leishmaniasis.

Canine Leishmaniasis (CanL) caused by the L. infantum species is one of the biggest threats to the health of the South American canine population. Chemotherapeutics currently used for the treatment of CanL fail to induce a total parasite clearance while inducing numerous side effects. As CanL is an immunomodulated disease, the use of immuno-treatments should strengthen the deficient immune response of infected dogs. In this study, we evaluated a nasally administered immunotherapy in dogs naturally infected with L. infantum (stage 2), with both visceral and cutaneous manifestations. Noteworthy, some of them were also infected by other parasites (E. canis, D. immitis, A. platys), what worsen their chance of survival. The treatment was based on 2 intranasal (IN.) administrations of a killed L. infantum parasite loaded into maltodextrin nanoparticles, which treatment was compared with the classical oral administration of Miltefosine (2 mg/kg) for 28 days, as well as a combination of these 2 treatments. The results showed that two IN administrations significantly reduced the serology, and were at least as efficient as the chemotherapy to reduce the skin and bone marrow parasite burden, as well as clinical scores, and that unlike Miltefosine treatments, this nasally administered nanoparticle vaccine was without side effects. These results confirm the feasibility of a simple therapeutic immuno-treatment against L. infantum infected dogs, which is a promising tool for future developments.

A tetravalent nanoparticle vaccine elicits a balanced and potent immune response against dengue viruses without inducing antibody-dependent enhancement.

Dengue fever is a global health threat caused by the dengue virus (DENV), a vector-borne and single-stranded RNA virus. Development of a safe and efficacious vaccine against DENV is a demanding challenge. The greatest pitfall in the development of vaccines is antibody-dependent enhancement (ADE), which is closely associated with disease exacerbation. We displayed the modified envelope proteins from the four serotypes of the DENV on a 24-mer ferritin nanoparticle, respectively. This tetravalent nanoparticle vaccine induced potent humoral and cellular immunity in mice without ADE and conferred efficient protection against the lethal challenge of DENV-2 and DENV-3 in AG6 mice. Further exploration of immunization strategies showed that even single-dose vaccination could reduce pathologic damage in BALB/c mice infected with high doses of DENV-2. Treatment with cyclic-di-guanosine monophosphate facilitated a higher titer of neutralizing antibodies and a stronger type-1 T-helper cell-biased immune response, thereby revealing it to be an effective adjuvant for dengue nanoparticle vaccines. These data suggest that a promising tetravalent nanoparticle vaccine could be produced to prevent DENV infection.

Homologous Sequential Immunization Using Salmonella Oral Administration Followed by an Intranasal Boost with Ferritin-Based Nanoparticles Enhanced the Humoral Immune Response against H1N1 Influenza Virus.

The influenza virus continues to pose a great threat to public health due to the frequent variations in RNA viruses. Vaccines targeting conserved epitopes, such as the extracellular domain of the transmembrane protein M2 (M2e), a nucleoprotein, and the stem region of hemagglutinin proteins, have been developed, but more efficient strategies, such as nanoparticle-based vaccines, are still urgently needed. However, the labor-intensive in vitro purification of nanoparticles is still necessary, which could hinder the application of nanoparticles in the veterinary field in the future. To overcome this limitation, we used regulated lysis Salmonella as an oral vector with which to deliver three copies of M2e (3M2e-H1N1)-ferritin nanoparticles in situ and evaluated the immune response. Then, sequential immunization using Salmonella-delivered nanoparticles followed by an intranasal boost with purified nanoparticles was performed to further improve the efficiency. Compared with 3M2e monomer administration, Salmonella-delivered in situ nanoparticles significantly increased the cellular immune response. Additionally, the results of sequential immunization showed that the intranasal boost with purified nanoparticles dramatically stimulated the activation of lung CD11b dendritic cells (DCs) and elevated the levels of effector memory T (TEM) cells in both spleen and lung tissues as well as those of CD4 and CD8 tissue-resident memory T (TRM) cells in the lungs. The increased production of mucosal IgG and IgA antibody titers was also observed, resulting in further improvements to protection against a virus challenge, compared with the pure oral immunization group. Salmonella-delivered in situ nanoparticles efficiently increased the cellular immune response, compared with the monomer, and sequential immunization further improved the systemic immune response, as shown by the activation of DCs, the production of TEM cells and TRM cells, and the mucosal immune response, thereby providing us with a novel strategy by which to apply nanoparticle-based vaccines in the future. IMPORTANCE Salmonella-delivered in situ nanoparticle platforms may provide novel nanoparticle vaccines for oral administration, which would be beneficial for veterinary applications. The combination of administering Salmonella-vectored, self-assembled nanoparticles and an intranasal boost with purified nanoparticles significantly increased the production of effector memory T cells and lung resident memory T cells, thereby providing partial protection against an influenza virus challenge. This novel strategy could open a novel avenue for the application of nanoparticle vaccines for veterinary purposes.

Combined Live Oral Priming and Intramuscular Boosting Regimen with Rotarix® and a Nanoparticle-Based Trivalent Rotavirus Vaccine Evaluated in Gnotobiotic Pig Models of G4P[6] and G1P[8] Human Rotavirus Infection.

Human rotavirus (HRV) is the causative agent of severe dehydrating diarrhea in children under the age of five, resulting in up to 215,000 deaths each year. These deaths almost exclusively occur in low- and middle-income countries where vaccine efficacy is the lowest due to chronic malnutrition, gut dysbiosis, and concurrent enteric viral infection. Parenteral vaccines for HRV are particularly attractive as they avoid many of the concerns associated with currently used live oral vaccines. In this study, a two-dose intramuscular (IM) regimen of the trivalent, nanoparticle-based, nonreplicating HRV vaccine (trivalent S60-VP8*), utilizing the shell (S) domain of the capsid of norovirus as an HRV VP8* antigen display platform, was evaluated for immunogenicity and protective efficacy against P[6] and P[8] HRV using gnotobiotic pig models. A prime-boost strategy using one dose of the oral Rotarix® vaccine, followed by one dose of the IM trivalent nanoparticle vaccine was also evaluated. Both regimens were highly immunogenic in inducing serum virus neutralizing, IgG, and IgA antibodies. The two vaccine regimens failed to confer significant protection against diarrhea; however, the prime-boost regimen significantly shortened the duration of virus shedding in pigs challenged orally with the virulent Wa (G1P[8]) HRV and significantly shortened the mean duration of virus shedding, mean peak titer, and area under the curve of virus shedding after challenge with Arg (G4P[6]) HRV. Prime-boost-vaccinated pigs challenged with P[8] HRV had significantly higher P[8]-specific IgG antibody-secreting cells (ASCs) in the spleen post-challenge. Prime-boost-vaccinated pigs challenged with P[6] HRV had significantly higher numbers of P[6]- and P[8]-specific IgG ASCs in the ileum, as well as significantly higher numbers of P[8]-specific IgA ASCs in the spleen post-challenge. These results suggest the promise of and warrant further investigation into the oral priming and parenteral boosting strategy for future HRV vaccines.

Nanoparticle geometry, immune memory, and antigen presentation determine the cross-reactive antibody response against sarbecoviruses

Abstract In response to the threat of emerging SARS-CoV-2 variants and SARS-like betacoronaviruses (sarbecoviruses), mosaic nanoparticles presenting receptor-binding domains (RBDs) of multiple sarbecoviruses have been developed to elicit cross-reactive antibodies that target conserved regions of the RBD. To better understand vaccination with these antigens, we developed a computational model of the humoral response to nanoparticle and spike antigens using a combination of molecular dynamics, Markov processes, and population dynamics simulations. Avidity is currently only accounted for by introducing a second arm on rate, but additional effects of avidity will be considered in the future. Our model agrees with titers measured from nanoparticle and spike vaccinations in animals as well as clinical data from mRNA vaccines. We then used our model to predict the effect of previous vaccinations with wildtype spike on nanoparticle vaccinations. Compared to naïve individuals, previously vaccinated individuals produce a higher cross-reactive titer on the first nanoparticle vaccination and a lower cross-reactive titer on the second. This difference is due to expansion of cross-reactive B cells and competition with strain-specific B cells from previous vaccinations. Furthermore, we find that a cocktail of homotypic nanoparticles produces the same cross-reactive titers as the mosaic nanoparticle, which is because cross-reactive B cells can bind a greater fraction of presented antigen and can survive successive rounds of selection when the nanoparticle density is low. Supported by grants from the National Science Foundation (1745302), NIH (1-R61- AI161805-01), and the Ragon Institute of MGH, MIT, and Harvard.

MRNA-adjuvanted Influenza A Vaccine Can Induce High Cellular Immunity and Cross Reactivity in Mice

Abstract In recent years, the great success of mRNA-based vaccines for SARS-CoV-2 revealed a potential future for safe and effective mRNA vaccine designs. Given the flexibility and accessibility of mRNA designs, adjuvants in mRNA forms may be applied to enhance immune response and generate better cross-protection. In this study, we fabricated an Influenza mRNA lipid nanoparticle (LNP) vaccine with Influenza A/Aichi/2/1968 (Aichi, H3N2) Hemagglutinin (HA) mRNA and cytokine-adjuvant mRNA (GIFT4 or CCL27). We found that two doses of immunization with mRNA-adjuvanted LNPs induced increased antigen-specific antibody titer and effective protection against Influenza A viruses in mice. The supplement of cytokine mRNAs (GIFT4 or CCL27) provided more robust immunogenicity, including more IL-4 and IFN-γ secreting T cells in the spleen and more IgG and IgA-secreting B cells in the bone marrow. The cytokine mRNA adjuvants also induced early activation of T and B cells in germinal centers. Thus, GIFT4 and CCL27 mRNAs are potential adjuvants for Influenza A mRNA vaccine to elicit higher and broader immune responses in mice.

A new H9 influenza virus mRNA vaccine elicits robust protective immunity against infection.

Avian influenza virus (AIV) poses a great threat to the poultry industry and public health. However commercial vaccines only provide limited immunity due to rapid virus mutation and rearrangement. Here, we developed an mRNA-lipid nanoparticle (mRNA-LNP) vaccine expressing AIV immunogenic protein hemagglutinin (HA) and also assessed its safety and immune-protection efficacy in vivo. Specifically, its safety was tested by inoculation of SPF chicken embryos and chicks, and there showed no clinical manifestations and pathological changes in both. As for the immune efficacy, the antibody titers, IFN-γ production levels, and viral loads in various organs were analyzed. The results showed that chickens in the mRNA-LNP-inoculated groups produced higher specific antibody titers compared with that in the control group by hemagglutination inhibition (HI) test. Meanwhile, the ELISpot assay demonstrated that the expression of IFN-γ was markedly induced in the mRNA-LNP group, and the viral loads in multiple organs were decreased. In addition, HE shows no obvious pathomorphological changes in the lungs of the mRNA-LNP-inoculated group. While, there was severe inflammatory cell infiltration in the DMEM-treated group instead. Taken together, the vaccine prepared in this study was safe and could trigger potent cellular and humoral immune response to defend against virus infection.

Genetic immunization with self-assembling SARS-CoV-2 Spike-HBsAg nanoparticles

Abstract As the COVID-19 pandemic continues to pose a great challenge to global health, more effective and durable vaccines are needed owing to the waning protection offered by the current available vaccines. Here we report highly immunogenic self-assembling hepatitis B surface antigen (HBsAg) nanoparticles displaying the ectodomain of SARS-CoV-2 WA1 S6P, the prefusion spike stabilized by six proline substitutions. Three self-assembling nanoparticle constructs with different linkers named CL1, CL2 and CL3 expressed well-formed nanoparticles in mammalian cells. These purified nanoparticles can bind diverse monoclonal antibodies (mAbs) specific to different domains of SARS-CoV-2 spike. Immunization by DNA electroporation of CL2 and CL3 in mice elicited significantly more potent and durable neutralizing antibody responses against diverse SARS-CoV-2 strains than non-nanoparticle forms of stabilized spikes, including SARS-CoV-2 S2P and S6P ectodomain and full-length S2P with its coding sequence matching mRNA-1273. Our data showed that genetic delivery of HBsAg based nanoparticle vaccines displaying SARS-CoV-2 spike can elicit potent and durable neutralizing antibody responses and highlight their potential as next generation genetic vaccine candidates against SARS-CoV-2. NIH Intramural Funding

Intranasal nanoparticle vaccine elicits protective immunity against Mycobacterium tuberculosis

Abstract Mucosal vaccines have the potential to elicit protective immune responses at the point of entry of respiratory pathogens thus preventing even the initial seed infection. Unlike licensed injectable vaccines, mucosal vaccines comprising protein subunits are only in the development stage. One of the primary challenges associated with mucosal vaccines has been the identification and characterization of safe yet effective mucosal adjuvants that can effectively prime multi-factorial mucosal immunity. In this study, we tested NanoSTING, a liposomal formulation of the endogenous activator of the stimulator of interferon genes (STING) pathway, cyclic guanosine adenosine monophosphate (cGAMP), as a mucosal adjuvant. Intranasal administration of this vaccine provides protection comparable to subcutaneous administration of the live attenuated Mycobacterium bovis vaccine strain Bacille–Calmette–Guérin (BCG) upon challenge with aerosolized Mycobacterium tuberculosis Erdman strain. Protection against the bacterium is likely due to CXCR3+ lung resident T cells that are known to be important for the control of bacterial infection. Intranasal delivery also induces IFNγ secreting CD4+ T cells in lung which is necessary for intracellular bactericidal activity. Our results indicate that NanoSTING adjuvanted protein vaccines can elicit a multi-factorial immune response that provides durable protection from infection by M. tuberculosis.

Understanding Mechanisms of Adjuvancy in Muscle by mRNA/Lipid Nanoparticles

Abstract Vaccines utilizing encapsulated mRNA within lipid nanoparticles (LNPs) have demonstrated unprecedented efficacy in clinical studies of mRNA-1273 and BNT162b2, two prominent vaccines developed against the S protein of SARS-CoV-2. Despite several Phase III trials offering deep clinical intuition about vaccine efficacy, the musculo-immune basis for elicitation of a strong germinal center response from mRNA/LNP vaccine remains unclear. Here, we characterize the trajectory of the immune response to an mRNA lipid nanoparticle vaccine, encapsulated in sm-102 (Moderna). Furthermore, we find that intramuscular administration of empty LNPs elicits a strong neutrophil and dendritic response within 24h. Additionally, we show that skeletal muscle may play a role in the early immune response to mRNA LNPs. Inflammatory LNPs thus contribute to the well-established role of RNA immunogenicity. Using a reporter of transduction, we show that both >10% of muscle-resident myeloid and lymphoid cells are directly transduced with mRNA vaccines, and that these cells play a crucial role in the downstream germinal center response. Transcriptomic measurements of muscle tissue reveal a direct role role of ionizable lipid operating as an adjuvant to induce this response. Using in vitro and molecular tools, these studies advance our understanding of the cellular and molecular basis for LNP-mediated inflammation and adjuvancy underpinning the exceptional clinical efficacy of mRNA/LNP vaccination.

Particulate characteristics of engineered nanoparticle vaccines modulate vaccine immunogenicity in an intranasal route

Abstract The intranasal route is an ideal vaccination route for preventing infectious respiratory diseases due to its capability of generating both mucosal immunity—the first line of defense against respiratory virus invasion—and systemic immunity. Protein antigens are poorly immunogenic when administered intranasally. Previously we found that polycationic polyethyleneimine (PEI)-hemagglutinin (HA) nanoparticles significantly enhanced influenza HA immunogenicity in an intranasal route. Herein, we prepared hybrid PEI-HA-lipid nanoparticles and investigated how particulate features influence their immunogenicity. We found that a phosphatidylserine-based lipid layer coating around PEI-HA nanoparticles made the particle negatively charged and eliminated the induced antibody responses, reflecting the importance of surface charges in the antibody induction. However, further incorporation of PAMP adjuvants (MPLA and cGAMP) substantially boosted humoral and cellular responses both mucosally and systemically. MPLA and cGAMP-co-loaded hybrid nanoparticles generated the most lung-resident CD8+ T memory cells among all groups. These nanoparticles showed distinct antigen delivery behavior and early immune responses in mouse lungs and NALTs. Only adjuvanted particles induced significant BMDC maturation and inflammatory cytokines secretion in vitro cultures. Studies on these particle vaccines’ protective efficacy are ongoing in mice. The role of particulate features in programming the immune responses would be further analyzed. Our study will provide perspectives for the development of intranasal particulate vaccines against infectious respiratory diseases. Supported by grants from NIH/NIAID (R01AI101047, R01AI116835, R01AI143844)

Induction of multivalent and balanced T cell responses by modular nanoshell vaccine technology

Abstract After the outbreak of COVID-19, cellular immunity has been shown to provide protection especially in breakthrough infection and B cell-deficient patients. Furthermore, durable cellular immunity targets conserved epitopes among SARS-CoV-2 variants or different coronavirus then inspiring an attractive strategy for vaccine development. However, how to simultaneously induce balanced T cell responses against multiple epitopes still needs to be elucidated. In this study, we sought to design a T cell-based vaccine that can adjust valency against different T cell epitopes. We selected seven SARS-CoV-2 specific short peptides as antigens, including I-Ab/H-2Kb/H-2Db restricted epitopes. Furthermore, we used PLGA nanoparticle as vaccine platform to achieve the precise loading of the indicated peptides. Mice were immunized with different combinations of peptides and splenocytes were used to access epitope specific-IFN gamma expressing CD8+ or CD4+ T cell responses. First, we confirmed the robust immunogenicity of each peptide. We then combined an equal amount of indicated epitope peptides and accessed the immunogenicity of each epitope in the combination. The results showed peptides compete with each other to induce T cell responses regardless of MHC allele and MHC class. In addition, dominant epitopes significantly suppressed the immunogenicity of the subdominant epitopes. Finally, by optimizing the antigen dose, nanoparticle vaccine induced more balanced T responses against all seven epitopes. Taking advantage of nanoparticle, our results reveal a viable strategy to induce multivalent T cell response. Furthermore, the result suggests that competition of T cell epitopes is one of the factors controlling cellular immunity.

Improvement of B Cell Responses by an HIV-1 Amphiphilic Polymer Nanovaccine.

The human immunodeficiency virus (HIV) has infected over 84 million people since its discovery and is a huge threat to human health. While an HIV vaccine is urgently needed to curb this devastating pandemic, it has been notoriously difficult to develop, partly due to the extraordinary high level of genetic variation of HIV. We designed a new HIV-1 envelope glycoprotein nanoparticle (Env/NP) vaccine using amphiphilic polymers. The Env/NP vaccine induced more potent and broader neutralizing activities against multiple HIV-1 subtypes. Moreover, it elicits similar neutralizing antibody responses after the storage at -80 °C, 4 °C or room temperature post lyophilization. These results demonstrate that the new Env/NP vaccine not only improves the HIV vaccine immune responses but also is stable under different storage conditions. This new nanovaccine approach can readily apply to other protein-based vaccines.

Self-replicating RNA nanoparticle vaccine elicits protective immune responses against SARS-CoV-2

The creation of safe and effective vaccines that induce potent cellular and humoral immune responses against SARS-CoV-2 is urgently needed to end the global COVID-19 epidemic. Here, we developed an alphavirus-derived self-replicating RNA (repRNA)-based vaccine platform encoding the receptor-binding domain (RBD) of SARS-CoV-2 spike glycoprotein. The repRNA triggers prolonged antigen expression compared with conventional mRNA due to the replication machinery of repRNA. To improve the delivery and vaccine efficacy of repRNA, we developed a self-assembling liposome-protamine-RNA (LPR) nanoparticle with highly efficient encapsulation and transfection of repRNA. LPR-repRNA vaccines substantially activated type I interferon response and innate immune signaling pathways. Subcutaneous immunization of LPR-repRNA-RBD led to prolonged antigen expression, stimulation of innate immune cells, and induction of germinal center response in draining lymph nodes. LPR-repRNA-RBD induced antigen-specific Tcell responses and skewed cellular immunity toward an effector memory CD8+ Tcell response. Immunizations with LPR-repRNA-RBD triggered the production of anti-RBD IgG antibodies and induced neutralizing antibody response against SARS-CoV-2 pseudovirus. LPR-repRNA-RBD vaccines reduced SARS-CoV-2 infection and lung inflammation in mice. Altogether, these data suggest that the LPR-repRNA platform can be a promising avenue for COVID-19 vaccine development.

A ferritin-based COVID-19 nanoparticle vaccine that elicits robust, durable, broad-spectrum neutralizing antisera in non-human primates

While the rapid development of COVID-19 vaccines has been a scientific triumph, the need remains for a globally available vaccine that provides longer-lasting immunity against present and future SARS-CoV-2 variants of concern (VOCs). Here, we describe DCFHP, a ferritin-based, protein-nanoparticle vaccine candidate that, when formulated with aluminum hydroxide as the sole adjuvant (DCFHP-alum), elicits potent and durable neutralizing antisera in non-human primates against known VOCs, including Omicron BQ.1, as well as against SARS-CoV-1. Following a booster ~one year after the initial immunization, DCFHP-alum elicits a robust anamnestic response. To enable global accessibility, we generated a cell line that can enable production of thousands of vaccine doses per liter of cell culture and show that DCFHP-alum maintains potency for at least 14 days at temperatures exceeding standard room temperature. DCFHP-alum has potential as a once-yearly (or less frequent) booster vaccine, and as a primary vaccine for pediatric use including in infants.

A Ferritin Nanoparticle-Based Zika Virus Vaccine Candidate Induces Robust Humoral and Cellular Immune Responses and Protects Mice from Lethal Virus Challenge.

The severe consequences of the Zika virus (ZIKV) infections resulting in congenital Zika syndrome in infants and the autoimmune Guillain-Barre syndrome in adults warrant the development of safe and efficacious vaccines and therapeutics. Currently, there are no approved treatment options for ZIKV infection. Herein, we describe the development of a bacterial ferritin-based nanoparticle vaccine candidate for ZIKV. The viral envelope (E) protein domain III (DIII) was fused in-frame at the amino-terminus of ferritin. The resulting nanoparticle displaying the DIII was examined for its ability to induce immune responses and protect vaccinated animals upon lethal virus challenge. Our results show that immunization of mice with a single dose of the nanoparticle vaccine candidate (zDIII-F) resulted in the robust induction of neutralizing antibody responses that protected the animals from the lethal ZIKV challenge. The antibodies neutralized infectivity of other ZIKV lineages indicating that the zDIII-F can confer heterologous protection. The vaccine candidate also induced a significantly higher frequency of interferon (IFN)-γ positive CD4 T cells and CD8 T cells suggesting that both humoral and cell-mediated immune responses were induced by the vaccine candidate. Although our studies showed that a soluble DIII vaccine candidate could also induce humoral and cell-mediated immunity and protect from lethal ZIKV challenge, the immune responses and protection conferred by the nanoparticle vaccine candidate were superior. Further, passive transfer of neutralizing antibodies from the vaccinated animals to naïve animals protected against lethal ZIKV challenge. Since previous studies have shown that antibodies directed at the DIII region of the E protein do not to induce antibody-dependent enhancement (ADE) of ZIKV or other related flavivirus infections, our studies support the use of the zDIII-F nanoparticle vaccine candidate for safe and enhanced immunological responses against ZIKV.

Ad26.COV2.S and SARS-CoV-2 spike protein ferritin nanoparticle vaccine protect against SARS-CoV-2 Omicron BA.5 challenge in macaques

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines demonstrate reduced protection against acquisition of BA.5 subvariant but are still effective against severe disease. However, immune correlates of protection against BA.5 remain unknown. We report the immunogenicity and protective efficacy of vaccine regimens consisting of the vector-based Ad26.COV2.S vaccine and the adjuvanted spike ferritin nanoparticle (SpFN) vaccine against a high-dose, mismatched Omicron BA.5 challenge in macaques. The SpFNx3 and Ad26+ SpFNx2 regimens elicit higher antibody responses than Ad26x3, whereas the Ad26+ SpFNx2 and Ad26x3 regimens induce higher CD8 Tcell responses than SpFNx3. The Ad26+ SpFNx2 regimen elicits the highest CD4 Tcell responses. All three regimens suppress peak and day 4 viral loads in the respiratory tract, which correlate with both humoral and cellular immune responses. This study demonstrates that both homologous and heterologous regimens involving Ad26.COV2.S and SpFN vaccines provide robust protection against a mismatched BA.5 challenge in macaques.