SARS-CoV-2 spike-based virus-like particles incorporate influenza H1/N1 antigens and induce dual immunity in mice.

A vaccine effective against both SARS-CoV-2 and influenza A (IAV) viruses could represent a cost-effective strategy to reduce their combined public health burden as well as potential complications arising from co-infection. Based on previous findings that full-length SARS-CoV-2 spike (S) expression can induce high-level, enveloped VLP (eVLP) production in CHO cells, we tested whether IAV H1N1 hemagglutinin (H1) and neuraminidase (N1) could also be displayed on these particles. We found that co-incorporation of the IAV surface antigens in spike VLPs (S-VLPs) was highly efficient: upon transient co-expression of S + H1 or S + H1 + N1 in CHO cells, the resulting VLPs contained similar amounts of the SARS-CoV-2 S and IAV antigens.

Sulfated lactosyl archaeol (SLA) archaeosomes as a vaccine adjuvant.

Archaeosomes are liposomes traditionally comprised of total polar lipids or semi-synthetic glycerolipids of ether-linked isoprenoid phytanyl cores with varied glycol- and amino-head groups. We have developed a semi-synthetic archaeosome formulation based on sulfated lactosylarchaeol (SLA) that can be readily synthesized and easily formulated to induce robust humoral and cell-mediated immunity following systemic immunization, enhancing protection in models of infectious disease and cancer. Liposomes composed of SLA have been shown to be a safe and effective vaccine adjuvant to a multitude of antigens in preclinical studies including hepatitis C virus E1/E2 glycoproteins, hepatitis B surface antigen, influenza hemagglutinin, Rabbit Hemorrhagic Disease Virus antigens, and SARS-CoV-2 Spike antigens based on the ancestral strain as well as multiple variants of concern.

Intranasal administration of unadjuvanted SARS-CoV-2 spike antigen boosts antigen-specific immune responses induced by parenteral protein subunit vaccine prime in mice and hamsters.

With the continued transmission of SARS-CoV-2 across widely vaccinated populations, it remains important to develop new vaccines and vaccination strategies capable of providing protective immunity and limiting the spread of disease. Heterologous prime-boost vaccination based on the selection of different vaccine formulations and administration routes for priming and booster doses presents a promising strategy for inducing broader immune responses in key systemic and respiratory mucosal compartments. Intranasal vaccination can induce mucosal immune responses at the site of SARS-CoV-2 infection; however, the lack of clinically approved mucosal adjuvants makes it difficult to induce robust immune responses with protein subunit vaccines.

Effectiveness of VSV vectored SARS-CoV-2 spike when administered through intranasal, intramuscular or a combination of both.

A critical feature of the VSV vector platform is the ability to pseudotype the virus with different glycoproteins from other viruses, thus altering cellular tropism of the recombinant virus. The route of administration is critical in triggering local and systemic immune response and protection. Most of the vaccine platforms used at the forefront are administered by intramuscular injection.

Production, purification and immunogenicity of Gag virus-like particles carrying SARS-CoV-2 components.

The virus-like particle (VLP) platform is a robust inducer of humoral and cellular immune responses; hence, it has been used in vaccine development for several infectious diseases. In the current work, VLPs carrying SARS-CoV-2 Spike (S) protein (Wuhan strain) with an HIV-1 Gag core were produced using suspension HEK 293SF-3F6 cells by transient transfection. The Gag was fused with green fluorescent protein (GFP) for rapid quantification of the VLPs.

Preclinical evaluation of manufacturable SARS-CoV-2 spike virus-like particles produced in Chinese Hamster Ovary cells.

Background: As the COVID-19 pandemic continues to evolve, novel vaccines need to be developed that are readily manufacturable and provide clinical efficacy against emerging SARS-CoV-2 variants. Virus-like particles (VLPs) presenting the spike antigen at their surface offer remarkable benefits over other vaccine antigen formats; however, current SARS-CoV-2 VLP vaccines candidates in clinical development suffer from challenges including low volumetric productivity, poor spike antigen density, expression platform-driven divergent protein glycosylation and complex upstream/downstream processing requirements. Despite their extensive use for therapeutic protein manufacturing and proven ability to produce enveloped VLPs, Chinese Hamster Ovary (CHO) cells are rarely used for the commercial production of VLP-based vaccines.

Sulfated Lactosyl Archaeol Archaeosome-Adjuvanted Vaccine Formulations Targeting Rabbit Hemorrhagic Disease Virus Are Immunogenic and Efficacious.

Vaccines play an important role in maintaining human and animal health worldwide. There is continued demand for effective and safe adjuvants capable of enhancing antigen-specific responses to a target pathogen. Rabbit hemorrhagic disease virus (RHDV) is a highly contagious calicivirus that often induces high mortality rates in rabbits.

Tuning the immune response: sulfated archaeal glycolipid archaeosomes as an effective vaccine adjuvant for induction of humoral and cell-mediated immunity towards the SARS-CoV-2 Omicron variant of concern.

Liposomes composed of sulfated lactosyl archaeol (SLA) have been shown to be a safe and effective vaccine adjuvant with a multitude of antigens in preclinical studies. In particular, SLA-adjuvanted SARS-CoV-2 subunit vaccines based on trimeric spike protein antigens were shown to be immunogenic and efficacious in mice and hamsters. With the continued emergence of SARS-CoV-2 variants, we sought to evaluate next-generation vaccine formulations with an updated antigenic identity.

Characterization of Systemic and Mucosal Humoral Immune Responses to an Adjuvanted Intranasal SARS-CoV-2 Protein Subunit Vaccine Candidate in Mice.

Continuous viral evolution of SARS-CoV-2 has resulted in variants capable of immune evasion, vaccine breakthrough infections and increased transmissibility. New vaccines that invoke mucosal immunity may provide a solution to reducing virus transmission. Here, we evaluated the immunogenicity of intranasally administered subunit protein vaccines composed of a stabilized SARS-CoV-2 spike trimer or the receptor binding domain (RBD) adjuvanted with either cholera toxin (CT) or an archaeal lipid mucosal adjuvant (AMVAD).

Blood-Based Immune Protein Markers of Disease Progression in Murine Models of Acute and Chronic Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD) is a chronic ailment afflicting millions of people worldwide, with the majority of recognized cases within industrialized countries. The impacts of IBD at the individual level are long-lasting with few effective treatments available, resulting in a large burden on the health care system. A number of existing animal models are utilized to evaluate novel treatment strategies.

Evaluation of Adjuvant Activity and Bio-Distribution of Archaeosomes Prepared Using Microfluidic Technology.

Archaeosomes, composed of sulfated lactosyl archaeol (SLA) glycolipids, have been proven to be an effective vaccine adjuvant in multiple preclinical models of infectious disease or cancer. They have classically been prepared using a thin-film hydration method with an average particle size of 100-200 nm. In this study, we developed methods to generate SLA archaeosomes at different sizes, i.

Intranasal immunization with a proteosome-adjuvanted SARS-CoV-2 spike protein-based vaccine is immunogenic and efficacious in mice and hamsters.

With the persistence of the SARS-CoV-2 pandemic and the emergence of novel variants, the development of novel vaccine formulations with enhanced immunogenicity profiles could help reduce disease burden in the future. Intranasally delivered vaccines offer a new modality to prevent SARS-CoV-2 infections through the induction of protective immune responses at the mucosal surface where viral entry occurs. Herein, we evaluated a novel protein subunit vaccine formulation containing a resistin-trimerized prefusion Spike antigen (SmT1v3) and a proteosome-based mucosal adjuvant (BDX301) formulated to enable intranasal immunization.

Effect of Chiral Purity on Adjuvanticity of Archaeol-Based Glycolipids.

Archaeosomes composed of sulfated lactosyl archaeol (SLA) glycolipids from stereoisomerically pure archaeol () are vaccine adjuvants that can boost immunogenicity and vaccine efficacy in preclinical models. Herein, we report a new synthesis of 2,3-bis((3,7,11,15-tetramethylhexadecyl)oxy) propan-1-ol () by treating (±)-3-benzyloxy-1,2-propanediol with a mesylated phytol derivative through a double nucleophilic substitution reaction, followed by reductive debenzylation. Three SLA archaeosomes from archaeols of different chiral purities were prepared, and the effect of stereochemistry on their adjuvanticity toward ovalbumin was investigated.

Generation of a Liposomal Vaccine Adjuvant Based on Sulfated S-Lactosylarchaeol (SLA) Glycolipids.

Vaccine formulations utilize adjuvants to enhance the level and breadth of the immune response to a target antigen. Liposomes composed of sulfated S-lactosylarchaeol (SLA) glycolipids can induce strong humoral and cell-mediated antigen-specific immune responses to co-administered antigens in mice. This has been demonstrated with a variety of protein antigens, where the protein is either encapsulated within or simply admixed with the archaeal liposomes (archaeosomes).

Adjuvants: Engineering Protective Immune Responses in Human and Veterinary Vaccines.

Adjuvants are key components of many vaccines, used to enhance the level and breadth of the immune response to a target antigen, thereby enhancing protection from the associated disease. In recent years, advances in our understanding of the innate and adaptive immune systems have allowed for the development of a number of novel adjuvants with differing mechanisms of action. Herein, we review adjuvants currently approved for human and veterinary use, describing their use and proposed mechanisms of action.

Immunogenic and efficacious SARS-CoV-2 vaccine based on resistin-trimerized spike antigen SmT1 and SLA archaeosome adjuvant.

The huge worldwide demand for vaccines targeting SARS-CoV-2 has necessitated the continued development of novel improved formulations capable of reducing the burden of the COVID-19 pandemic. Herein, we evaluated novel protein subunit vaccine formulations containing a resistin-trimerized spike antigen, SmT1. When combined with sulfated lactosyl archaeol (SLA) archaeosome adjuvant, formulations induced robust antigen-specific humoral and cellular immune responses in mice.

Sulfated Lactosyl Archaeol Archaeosomes Synergize with Poly(I:C) to Enhance the Immunogenicity and Efficacy of a Synthetic Long Peptide-Based Vaccine in a Melanoma Tumor Model.

Cancer remains a leading cause of morbidity and mortality worldwide. While novel treatments have improved survival outcomes for some patients, new treatment modalities/platforms are needed to combat a wider variety of tumor types. Cancer vaccines harness the power of the immune system to generate targeted tumor-specific immune responses.

The Synergistic Effects of Sulfated Lactosyl Archaeol Archaeosomes When Combined with Different Adjuvants in a Murine Model.

Archaeosomes, composed of sulfated lactosyl archaeol (SLA) glycolipids, have been proven to be an effective vaccine adjuvant in multiple preclinical models of infectious disease or cancer. SLA archaeosomes are a promising adjuvant candidate due to their ability to strongly stimulate both humoral and cytotoxic immune responses when simply admixed with an antigen. In the present study, we evaluated whether the adjuvant effects of SLA archaeosomes could be further enhanced when combined with other adjuvants.

Measurement of Antigen-Specific IgG Titers by Direct ELISA.

Direct ELISA allows for the measurement of antibody levels to a particular antigen. Serum or plasma from the vaccinated subject are incubated on high-binding capacity microplates precoated with the antigen of interest and detected utilizing an enzyme-linked secondary antibody. Herein, using influenza hemagglutinin as model antigen, we describe the quantification of antigen-specific IgG titers in mouse serum to measure vaccine-induced humoral responses.

The Quantification of Antigen-Specific T Cells by IFN-γ ELISpot.

The enzyme-linked immune absorbent spot (ELISpot) assay allows for the quantification of the number of cells producing a particular secreted analyte. As T lymphocytes secrete cytokines such as interferon (IFN)-γ upon binding of the T cell receptor with its cognate antigen epitope, IFN-γ ELISpot allows for the measurement of antigen-specific T cells in an immune sample. Immune cells are isolated from the vaccinated subject and incubated with the epitope/antigen of interest on polyvinylidene difluoride (PVDF)-lined microplates precoated with a capture antibody to IFN-γ.

Methods to Evaluate Immune Cell Recruitment and Cellular Uptake and Distribution of Antigen Following Intramuscular Administration of Vaccine to Mice.

An effective vaccine depends on the stimulation of the immune system to generate effective antigen-specific immune responses capable of neutralizing mediators of disease long after vaccination. However, the ability of the vaccine to enhance immune parameters such as cell activation, cell recruitment and antigen uptake shortly following administration contributes to the development of long-term responses directed toward the antigen. Here, we describe a flow cytometry-based method to identify changes in immune cell profile and assess cellular uptake and distribution of antigen following vaccination.

Mechanistic insight into the induction of cellular immune responses by encapsulated and admixed archaeosome-based vaccine formulations.

Archaeosomes are liposomes formulated using total polar lipids (TPLs) or semi-synthetic glycolipids derived from archaea. Conventional archaeosomes with entrapped antigen exhibit robust adjuvant activity as demonstrated by increased antigen-specific humoral and cell-mediated responses and enhanced protective immunity in various murine infection and cancer models. However, antigen entrapment efficiency can vary greatly resulting in antigen loss during formulation and variable antigen:lipid ratios.

Assessment of stability of sulphated lactosyl archaeol archaeosomes for use as a vaccine adjuvant.

Archaeosomes, composed of sulphated lactosyl archaeol (SLA) glycolipids, have been proven to be an effective vaccine adjuvant in multiple preclinical models of infectious disease or cancer. In addition to efficacy, the stability of vaccine components including the adjuvant is an important parameter to consider when developing novel vaccine formulations. To properly evaluate the potential of SLA glycolipids to be used as vaccine adjuvants in a clinical setting, a comprehensive evaluation of their stability is required.

Effect of Different Adjuvants on the Longevity and Strength of Humoral and Cellular Immune Responses to the HCV Envelope Glycoproteins.

Infection by Hepatitis C virus (HCV) can lead to liver cirrhosis/hepatocellular carcinoma and remains a major cause of serious disease morbidity and mortality worldwide. However, current treatment regimens remain inaccessible to most patients, particularly in developing countries, and, therefore, the development of a novel vaccine capable of protecting subjects from chronic infection by HCV could greatly reduce the rates of HCV infection, subsequent liver pathogenesis, and in some cases death. Herein, we evaluated two different semi-synthetic archaeosome formulations as an adjuvant to the E1/E2 HCV envelope protein in a murine model and compared antigen-specific humoral (levels of anti-E1/E2 IgG and HCV pseudoparticle neutralization) and cellular responses (numbers of antigen-specific cytokine-producing T cells) to those generated with adjuvant formulations composed of mimetics of commercial adjuvants including a squalene oil-in-water emulsion, aluminum hydroxide/monophosphoryl lipid A (MPLA) and liposome/MPLA/QS-21.