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Adjuvants are essential components of vaccines as they enable protection against multiple pathogens by enhancing the duration, magnitude and or quality of immune responses. SLA Archaeosomes, a type of liposome composed of sulfated lactosyl archaeol (SLA) glycolipids, are highly stable vaccine adjuvants that have been shown to induce strong immune responses in preclinical models of infectious disease and cancer. To better understand the mechanism of activity behind SLA archaeosomes strong immunogenic properties, we studied the effect of structural change on vaccine adjuvanticity. Herein, we report the synthesis of three new sulfated lactosyl glycosides (SLGs) by replacing the archaeol moiety with various side-chains. These derivatives were characterized using nuclear magnetic resonance, mass spectrometry, and thin layer chromatography for identity and purity assessment. The SLGs were co-assembled in the presence of DMPC and cholesterol to produce lipid vesicles. The abilities of the SLG-based liposomes to act as vaccine adjuvants were compared to SLA archaeosomes in an in vivo murine vaccine model. [ABSTRACT FROM AUTHOR]

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. Herein, we evaluated the long term stability of preformed empty SLA archaeosomes prior to admixing with antigen at 4 °C or 37 °C for up to 6 months. In addition, the stability of adjuvant and antigen was evaluated for up to 1 month following admixing. Multiple analytical parameters evaluating the molecular integrity of SLA and the liposomal profile were assessed. Following incubation at 4 °C or 37 °C, the SLA glycolipid did not show any pattern of degradation as determined by mass spectroscopy, nuclear magnetic resonance (NMR) and thin layer chromatography (TLC). In addition, SLA archaeosome vesicle characteristics, such as size, zeta potential, membrane fluidity and vesicular morphology, were largely consistent throughout the course of the study. Importantly, following storage for 6 months at both 4 °C and 37 °C, the adjuvant properties of empty SLA archaeosomes were unchanged, and following admixing with antigen, the immunogenicity of the vaccine formulations was also unchanged when stored at both 4 °C and 37 °C for up to 1 month. Overall this indicates that SLA archaeosomes are highly stable adjuvants that retain their activity over an extended period of time even when stored at high temperatures. [ABSTRACT FROM AUTHOR]

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. The self-assembled bivalent (S/H1) and trivalent (S/H1/N1) VLPs released into the culture media were purified by single-step chromatography using a S-VLP affinity resin. Western blot analysis and immuno‑gold labeling transmission electron microscopy (TEM) of purified VLPs confirmed the coexistence of S, H1 and N1 antigens in the same particles. Finally, we demonstrated that two doses of adjuvanted bivalent and trivalent VLPs elicit specific functional antibodies and cellular immunity in a mouse model, suggesting potential for combined SARS-CoV-2/IAV vaccine development., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Zalma Sanchez reports financial support was provided by Natural Sciences and Engineering Research Council of Canada via the NSERC-CREATE PrEEmiuM program. Yves Durocher, Matthew Stuible, Sergio Alpuche-Lazcano, Zalma Sanchez has patent #ENVELOPED VIRUS LIKE PARTICLES COMPRISING SARS-COV-2 S PROTEIN pending to National Research Council Canada. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2024. Published by Elsevier Ltd. All rights reserved.)

Herein, a method to measure in vivo CD8 + T cell cytotoxicity in a murine model is presented. The activation of a strong CD8 + T cell response is paramount when designing vaccines to tackle intracellular infections and for cancer therapy. CD8 + T cells can directly kill infected and transformed cells and are directly associated with beneficial protection in many disease models. CD8 + T cell cytotoxicity can be measured using multiple methods including measuring IFNγ production by ELISPOT or measuring intracellular cytokines or cytotoxic granules by flow cytometry. However, to determine the ability of CD8 + T cells to kill their target in the context of its cognate receptor and in their native environment, the in vivo cytotoxic T cell assay (in vivo CTL) is ideal. The in vivo CTL assay provides a snapshot of the whole ability of the host to kill "Target" cells by measuring the loss of injected target cells relative to "Non-target" cells. The assay involves isolating splenocytes from donor mice, forming "Target" and "Non-target" cellular samples and injecting them intravenously into naïve and experimental mice at a chosen time-point in the experiment. Mice are humanely sacrificed 20 h later, and their spleens are excised and processed for flow cytometric analysis. The extent of "Target" cell killing relative to "Non-target" cells is determined by comparing the surviving proportions of these cells among experimental mice relative to naïve mice. The in vivo CTL assay is a rapid, sensitive, and reliable method to measure the potency of CD8 + T cells in their host to kill their target.