Newcastle disease virus-like particles induce DC maturation through TLR4/NF-κB pathway and facilitate DC migration by CCR7-CCL19/CCL21 axis. Qian Jing,Xu Xiaohong,Ding Jiaxin,Yin Renfu,Sun Yixue,Xue Cong,Wang Jianzhong,Ding Chan,Yu Shengqing,Liu Xiufan,Hu Shunlin,Wang Chunfeng,Cong Yanlong,Ding Zhuang Veterinary microbiology Newcastle disease virus-like particles (NDV VLPs) are a potential candidate vaccine, as shown by eliciting specific immune response against NDV in mice and chickens. Activation of dendritic cells (DCs) is critical to initiate immune response. However, the mechanism of how NDV VLPs induce DC maturation and migration remains elusive. In this study, we found that NDV VLPs are efficient in DC activation by up-regulating surface MHC II and costimulatory molecules, and proinflammatory cytokines through the TLR4/NF-κB pathway. Furthermore, NDV VLPs elevated CCR7 expression on DCs, resulting in DC migration towards CCL19/CCL21 both in vitro and ex vivo. As a consequence of DC maturation and migration, CD4+ T cells were also activated in vivo, demonstrating increased intracellular IFN-γ and IL-4 levels. Together, these results present new insights for NDV VLPs induced DC maturation and migration, providing a better understanding of VLP-triggered innate immune responses. 10.1016/j.vetmic.2017.03.002

Stimulation Effects and Mechanisms of Different Adjuvants on a Norovirus P Particle-Based Active Amyloid-β Vaccine. Dai MingRui,Feng XueJian,Mo ZengShuo,Sun Yao,Fu Lu,Zhang Yong,Wu Jiaxin,Yu Bin,Zhang Haihong,Yu Xianghui,Wu Hui,Kong Wei Journal of Alzheimer's disease : JAD BACKGROUND:Adjuvants are important components of vaccines and effectively enhance the immune response of specific antigens. However, the role of adjuvants or combinations of adjuvants in stimulating immunogenicity of the amyloid-β (Aβ) vaccine, as well as molecular mechanisms underlying such stimulation still remain unclear. A previous study of ours developed a norovirus P particle-based active Aβ epitope vaccine, PP-3copy-Aβ1-6-loop123, which stimulates a high titer of Aβ-specific antibodies in mouse Alzheimer's disease (AD) models. OBJECTIVE:The most effective and safe adjuvant that maximizes the immunogenicity of our protein vaccine was determined. METHODS:We investigated four adjuvants (CpG, AS02, AS03, and MF59), and combinations of those, for capacity to enhance immunogenicity, and performed transcriptome analysis to explore mechanisms underlying the role of these in AD immunotherapy. RESULTS:Addition of the adjuvant, AS02, remarkably improved the immunogenicity of the PP-3copy-Aβ1-6-loop123 vaccine without triggering an Aβ-specific T-cell response. Combinations of adjuvants, particularly CpG +  AS02 and CpG + AS03, elicited a significantly elevated and prolonged Aβ-specific antibody response. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses indicated that a combination of two adjuvants was more effective in activating immune-related pathways, thereby enhancing the immunogenicity of PP-3copy-Aβ1-6-loop123. CONCLUSION:These findings demonstrated that adjuvants can be used as enhancers in AD protein vaccination, and that a combination of CpG and AS-related adjuvants may be a very effective adjuvant candidate suitable for further clinical trials of the PP-3copy-Aβ1-6-loop123 vaccine. Our studies also revealed potential mechanisms underlying the stimulation of immune response of protein vaccines by adjuvants. 10.3233/JAD-200351

In vivo, dendritic cells can cross-present virus-like particles using an endosome-to-cytosol pathway. Morón Víctor Gabriel,Rueda Paloma,Sedlik Christine,Leclerc Claude Journal of immunology (Baltimore, Md. : 1950) Recombinant parvovirus-like particles (PPV-VLPs) are particulate exogenous Ags that induce strong CTL response in the absence of adjuvant. In the present report to decipher the mechanisms responsible for CTL activation by such exogenous Ag, we analyzed ex vivo and in vitro the mechanisms of capture and processing of PPV-VLPs by dendritic cells (DCs). In vivo, PPV-VLPs are very efficiently captured by CD8alpha- and CD8alpha+ DCs and then localize in late endosomes of DCs. Macropinocytosis and lipid rafts participate in PPV-VLPs capture. Processing of PPV-VLPs does not depend upon recycling of MHC class I molecules, but requires vacuolar acidification as well as proteasome activity, TAP translocation, and neosynthesis of MHC class I molecules. This study therefore shows that in vivo DCs can cross-present PPV-VLPs using an endosome-to-cytosol processing pathway. 10.4049/jimmunol.171.5.2242

Lipid nanoparticles as adjuvant of norovirus VLP vaccine augment cellular and humoral immune responses in a TLR9- and type I IFN-dependent pathway. Journal of virology Norovirus (NoV) virus-like particles (VLPs) adjuvanted with aluminum hydroxide (Alum) are common vaccine candidates in clinical studies. Alum adjuvants usually inefficiently assist recombinant proteins to induce cellular immune responses. Thus, novel adjuvants are required to develop NoV vaccines that could induce both efficient humoral and robust cellular immune responses. Lipid nanoparticles (LNPs) are well-known mRNA delivery vehicles. Increasing evidence suggests that LNPs may have intrinsic adjuvant activity and can be used as adjuvants for recombinant protein vaccines; however, the underlying mechanism remains poorly understood. In this study, we compared the adjuvant effect of LNPs and Alum for a bivalent GI.1/GII.4 NoV VLP vaccine. Compared with Alum, LNP-adjuvanted vaccines induced earlier production of binding, blocking, and neutralizing antibodies and promoted a more balanced IgG2a/IgG1 ratio. It is crucial that LNP-adjuvanted vaccines induced stronger Th1-type cytokine-producing CD4 T cell and CD8 T cell responses than Alum. The adjuvant activity of LNPs depended on the ionizable lipid components. Mechanistically, LNPs activated innate immune responses in a type I IFN-dependent manner and were partially dependent on Toll-like receptor (TLR) 9, thus affecting the adaptive immune responses of the vaccine. This conclusion was supported by RNA-seq analysis and cell experiments and by the deeply blunted T cell responses in IFNαR1 mice immunized with LNP-adjuvanted vaccines. This study not only identified LNPs as a high quality adjuvant for NoV VLP vaccines, but also clarified the underlying mechanism of LNPs as a potent immunostimulatory component for improving protein subunit vaccines.IMPORTANCEWith the rapid development of mRNA vaccines, recurrent studies show that lipid nanoparticles (LNPs) have adjuvant activity. However, the mechanism of its adjuvant effect in protein vaccines remains unknown. In this study, we found that the LNP-adjuvanted norovirus bivalent virus-like particle vaccines led to durable antibody responses as well as Th1-type cytokine-producing CD4 T cell and CD8 T cell responses, which exceeded the efficiency of the conventional adjuvant aluminum hydroxide. Mechanistically, LNPs activated innate immune responses in a type I IFN-dependent manner and were partially dependent on Toll-like receptor 9, thus affecting the adaptive immune responses of the vaccine. This work unveils that LNPs as a potent immunostimulatory component may be ideal for generating CD8 T cell and B cell responses for recombinant protein vaccines. 10.1128/jvi.01699-24

BCG vaccination stimulates integrated organ immunity by feedback of the adaptive immune response to imprint prolonged innate antiviral resistance. Nature immunology Bacille Calmette-Guérin (BCG) vaccination can confer nonspecific protection against heterologous pathogens. However, the underlying mechanisms remain mysterious. We show that mice vaccinated intravenously with BCG exhibited reduced weight loss and/or improved viral clearance when challenged with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 B.1.351) or PR8 influenza. Protection was first evident between 14 and 21 d post-vaccination and lasted ∼3 months. Notably, BCG induced a biphasic innate response and robust antigen-specific type 1 helper T cell (T1 cell) responses in the lungs. MyD88 signaling was essential for innate and T1 cell responses, and protection against SARS-CoV-2. Depletion of CD4 T cells or interferon (IFN)-γ activity before infection obliterated innate activation and protection. Single-cell and spatial transcriptomics revealed CD4-dependent expression of IFN-stimulated genes in lung myeloid and epithelial cells. Notably, BCG also induced protection against weight loss after mouse-adapted SARS-CoV-2 BA.5, SARS-CoV and SHC014 coronavirus infections. Thus, BCG elicits integrated organ immunity, where CD4 T cells feed back on tissue myeloid and epithelial cells to imprint prolonged and broad innate antiviral resistance. 10.1038/s41590-023-01700-0