{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,21]],"date-time":"2026-10-21T22:39:05Z","timestamp":1792622345314,"version":"4.5.0"},"reference-count":32,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2026,6,25]],"date-time":"2026-06-25T00:00:00Z","timestamp":1782345600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003668","name":"Korea Institute of Planning and Evaluation for Technology in Food, Agriculture and Forestry","doi-asserted-by":"publisher","award":["RS-2025-02304147"],"award-info":[{"award-number":["RS-2025-02304147"]}],"id":[{"id":"10.13039\/501100003668","id-type":"DOI","asserted-by":"publisher"}]},{"award":["RS-2025-02304147"],"award-info":[{"award-number":["RS-2025-02304147"]}],"id":[{"id":"https:\/\/ror.org\/00c25dn03","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vaccines"],"abstract":"<jats:p>Background: Lipopolysaccharide (LPS) functions as a Toll-like receptor 4 (TLR4) agonist that triggers innate immunity; however, structural variations between pathogenic and commensal bacteria distinctly influence its immunostimulatory profile. This study evaluated the immunostimulatory activity of LPS derived from the commensal bacterium Hafnia alvei and explored its potential as an exploratory vaccine adjuvant. Methods: Cytokine induction was evaluated in immune cells across diverse host species, and receptor activation was assessed via reporter assays. To investigate in vivo immunogenicity and preliminary tolerability, H. alvei LPS was formulated into a prototype oil-in-water (O\/W) emulsion utilizing ovalbumin (OVA) as a model antigen. Results: LPS from H. alvei strain BA2000346 exhibited immunostimulatory activity comparable to that of Escherichia coli, while inducing greater TNF-\u03b1 expression than pathogenic Salmonella and Pseudomonas strains. Distinct from E. coli LPS, it demonstrated the capacity to activate both TLR4 and the mannose-recognizing Dectin-2 receptor in reporter systems. This cytokine induction was consistent across various strains and host species. Furthermore, the prototype O\/W emulsion formulation enhanced antigen-specific humoral and cellular immune responses while demonstrating preliminary tolerability based on body-weight monitoring and visual clinical observation. Conclusions: H. alvei-derived LPS exhibits TLR4 and Dectin-2 agonist activity in vitro. When synergized with an O\/W emulsion delivery system, it provides a preliminary indication of cross-species stimulatory potential and supports further investigation as a hypothesis-generating platform for future vaccine adjuvant development.<\/jats:p>","DOI":"10.3390\/vaccines14070557","type":"journal-article","created":{"date-parts":[[2026,6,25]],"date-time":"2026-06-25T08:14:12Z","timestamp":1782375252000},"page":"557","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Immunogenicity of an Oil-in-Water Emulsion Containing Hafnia Alvei-Derived Lipopolysaccharide, with TLR4 and Dectin-2 Agonist Activity In Vitro"],"prefix":"10.3390","volume":"14","author":[{"given":"Ri Ra","family":"Hong","sequence":"first","affiliation":[{"name":"Eutilex Co., Ltd., Gasan Digital 1-Ro 58, Geumcheon-gu, Seoul 08591, Republic of Korea"},{"name":"College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eun Ji","family":"Lee","sequence":"additional","affiliation":[{"name":"Eutilex Co., Ltd., Gasan Digital 1-Ro 58, Geumcheon-gu, Seoul 08591, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ji Hee","family":"Kwon","sequence":"additional","affiliation":[{"name":"Eutilex Co., Ltd., Gasan Digital 1-Ro 58, Geumcheon-gu, Seoul 08591, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sun Woo","family":"Im","sequence":"additional","affiliation":[{"name":"Eutilex Co., Ltd., Gasan Digital 1-Ro 58, Geumcheon-gu, Seoul 08591, Republic of Korea"},{"name":"KELGEN Inc., Hana-ro 820-120, Iksan-si 54531, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yeji","family":"Nam","sequence":"additional","affiliation":[{"name":"Eutilex Co., Ltd., Gasan Digital 1-Ro 58, Geumcheon-gu, Seoul 08591, Republic of Korea"},{"name":"KELGEN Inc., Hana-ro 820-120, Iksan-si 54531, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hyun-Tae","family":"Son","sequence":"additional","affiliation":[{"name":"Eutilex Co., Ltd., Gasan Digital 1-Ro 58, Geumcheon-gu, Seoul 08591, Republic of Korea"},{"name":"College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eunhye","family":"Yoo","sequence":"additional","affiliation":[{"name":"Eutilex Co., Ltd., Gasan Digital 1-Ro 58, Geumcheon-gu, Seoul 08591, Republic of Korea"},{"name":"KELGEN Inc., Hana-ro 820-120, Iksan-si 54531, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1081-7933","authenticated-orcid":false,"given":"Hyung Tae","family":"Lee","sequence":"additional","affiliation":[{"name":"Eutilex Co., Ltd., Gasan Digital 1-Ro 58, Geumcheon-gu, Seoul 08591, Republic of Korea"},{"name":"KELGEN Inc., Hana-ro 820-120, Iksan-si 54531, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"927","DOI":"10.1099\/jmm.0.038943-0","article-title":"Alum adjuvant: Some of the tricks of the oldest adjuvant","volume":"61","author":"Kool","year":"2012","journal-title":"J. Med. Microbiol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"497","DOI":"10.1111\/j.0818-9641.2004.01286.x","article-title":"Aluminium compounds for use in vaccines","volume":"82","author":"Lindblad","year":"2004","journal-title":"Immunol. Cell Biol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"6448","DOI":"10.4049\/jimmunol.163.12.6448","article-title":"Aluminium hydroxide adjuvant initiates strong antigen-specific Th2 responses in the absence of IL-4- or IL-13-mediated signaling","volume":"163","author":"Brewer","year":"1999","journal-title":"J. Immunol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1573","DOI":"10.1002\/eji.201041126","article-title":"Selective effects of NF-kappaB1 deficiency in CD4(+) T cells on Th2 and TFh induction by alum-precipitated protein vaccines","volume":"41","author":"Serre","year":"2011","journal-title":"Eur. J. Immunol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"454","DOI":"10.1038\/s41573-021-00163-y","article-title":"Emerging concepts in the science of vaccine adjuvants","volume":"20","author":"Pulendran","year":"2021","journal-title":"Nat. Rev. Drug Discov."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"283","DOI":"10.1038\/s41392-023-01557-7","article-title":"Vaccine adjuvants: Mechanisms and platforms","volume":"8","author":"Zhao","year":"2023","journal-title":"Signal Transduct. Target. Ther."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1597","DOI":"10.1038\/nm.3409","article-title":"Key roles of adjuvants in modern vaccines","volume":"19","author":"Reed","year":"2013","journal-title":"Nat. Med."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Ong, G.H., Lian, B.S.X., Kawasaki, T., and Kawai, T. (2021). Exploration of Pattern Recognition Receptor Agonists as Candidate Adjuvants. Front. Cell Infect. Microbiol., 11.","DOI":"10.3389\/fcimb.2021.745016"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"3231","DOI":"10.1007\/s00018-008-8228-6","article-title":"Putting endotoxin to work for us: Monophosphoryl lipid A as a safe and effective vaccine adjuvant","volume":"65","author":"Casella","year":"2008","journal-title":"Cell Mol. Life Sci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"10593","DOI":"10.1074\/jbc.REV120.009402","article-title":"Lipopolysaccharide O-antigens-bacterial glycans made to measure","volume":"295","author":"Whitfield","year":"2020","journal-title":"J. Biol. Chem."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"uqac011","DOI":"10.1093\/femsml\/uqac011","article-title":"Lipid A heterogeneity and its role in the host interactions with pathogenic and commensal bacteria","volume":"3","author":"Saha","year":"2022","journal-title":"Microlife"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"672","DOI":"10.1189\/jlb.0607432","article-title":"Early and preferential induction of IL-1 receptor-associated kinase-M in THP-1 cells by LPS derived from Porphyromonas gingivalis","volume":"83","author":"Domon","year":"2008","journal-title":"J. Leukoc. Biol."},{"key":"ref_13","first-page":"83","article-title":"Bacterial lipopolysaccharides: Extraction with phenol-water and further applications of the procedure","volume":"5","author":"Westphal","year":"1965","journal-title":"Methods Carbohydr. Chem."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"245","DOI":"10.1111\/j.1432-1033.1969.tb00601.x","article-title":"A new method for the extraction of R lipopolysaccharides","volume":"9","author":"Galanos","year":"1969","journal-title":"Eur. J. Biochem."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"17629","DOI":"10.1074\/jbc.M116.741256","article-title":"Dectin-2 Recognizes Mannosylated O-antigens of Human Opportunistic Pathogens and Augments Lipopolysaccharide Activation of Myeloid Cells","volume":"291","author":"Wittmann","year":"2016","journal-title":"J. Biol. Chem."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1038\/s41541-025-01076-2","article-title":"Cellular immune breadth of an Omicron-specific, self-amplifying monovalent mRNA vaccine booster for COVID-19","volume":"10","author":"Kumar","year":"2025","journal-title":"npj Vaccines"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Li, P., Shen, Y., Wang, T., Li, J., Li, Y., Zhao, Y., Liu, S., Li, B., Liu, M., and Meng, F. (2022). Epidemiological survey of PRRS and genetic variation analysis of the ORF5 gene in Shandong Province, 2020\u20132021. Front. Vet. Sci., 9.","DOI":"10.3389\/fvets.2022.987667"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"127793","DOI":"10.1016\/j.vaccine.2025.127793","article-title":"T cell-mediated clearance of porcine reproductive and respiratory syndrome virus (PRRSV) from the lung characterized by machine learning analysis in vaccinated and unvaccinated pigs","volume":"65","author":"Noel","year":"2025","journal-title":"Vaccine"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Paston, S.J., Brentville, V.A., Symonds, P., and Durrant, L.G. (2021). Cancer Vaccines, Adjuvants, and Delivery Systems. Front. Immunol., 12.","DOI":"10.3389\/fimmu.2021.627932"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"772","DOI":"10.1016\/j.immuni.2024.03.015","article-title":"Vaccine adjuvants: Tailoring innate recognition to send the right message","volume":"57","author":"Lavelle","year":"2024","journal-title":"Immunity"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"2517137","DOI":"10.1080\/10717544.2025.2517137","article-title":"Advances in vaccine adjuvant development and future perspectives","volume":"32","author":"Sinani","year":"2025","journal-title":"Drug Deliv."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Vaure, C., and Liu, Y. (2014). A comparative review of toll-like receptor 4 expression and functionality in different animal species. Front. Immunol., 5.","DOI":"10.3389\/fimmu.2014.00316"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"5271","DOI":"10.1016\/S0021-9258(18)89017-2","article-title":"Monophosphoryl lipid A obtained from lipopolysaccharides of Salmonella minnesota R595. Purification of the dimethyl derivative by high performance liquid chromatography and complete structural determination","volume":"260","author":"Qureshi","year":"1985","journal-title":"J. Biol. Chem."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"12261","DOI":"10.1021\/acs.jmedchem.1c00896","article-title":"Synthetic Glycolipids as Molecular Vaccine Adjuvants: Mechanism of Action in Human Cells and In Vivo Activity","volume":"64","author":"Facchini","year":"2021","journal-title":"J. Med. Chem."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"5956","DOI":"10.1016\/j.vaccine.2009.07.081","article-title":"Enhanced humoral and Type 1 cellular immune responses with Fluzone adjuvanted with a synthetic TLR4 agonist formulated in an emulsion","volume":"27","author":"Baldwin","year":"2009","journal-title":"Vaccine"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"109703","DOI":"10.1016\/j.ijfoodmicro.2022.109703","article-title":"Characterization of autochthonal Hafnia spp. strains isolated from Spanish soft raw ewe\u2019s milk PDO cheeses to be used as adjunct culture","volume":"373","author":"Merchan","year":"2022","journal-title":"Int. J. Food Microbiol."},{"key":"ref_27","first-page":"78","article-title":"Isolation of Hafnia species from kimchi","volume":"19","author":"Kwon","year":"2009","journal-title":"J. Microbiol. Biotechnol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"4293","DOI":"10.1128\/AEM.70.7.4293-4302.2004","article-title":"Presence of acylated homoserine lactones (AHLs) and AHL-producing bacteria in meat and potential role of AHL in spoilage of meat","volume":"70","author":"Bruhn","year":"2004","journal-title":"Appl. Environ. Microbiol."},{"key":"ref_29","unstructured":"Dechelotte, P., Breton, J., Trotin-Picolo, C., Grube, B., Erlenbeck, C., Bothe, G., Fetissov, S.O., and Lambert, G. (2021). The Probiotic Strain H. alvei HA4597((R)) Improves Weight Loss in Overweight Subjects under Moderate Hypocaloric Diet: A Proof-of-Concept, Multicenter Randomized, Double-Blind Placebo-Controlled Study. Nutrients, 13."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1041","DOI":"10.1038\/s41366-019-0515-9","article-title":"Commensal Hafnia alvei strain reduces food intake and fat mass in obese mice-a new potential probiotic for appetite and body weight management","volume":"44","author":"Legrand","year":"2020","journal-title":"Int. J. Obes."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"241","DOI":"10.1038\/nri2301","article-title":"TLR4 signalling","volume":"8","author":"Bell","year":"2008","journal-title":"Nat. Rev. Immunol."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2037","DOI":"10.1084\/jem.20082818","article-title":"Dectin-2 is a Syk-coupled pattern recognition receptor crucial for Th17 responses to fungal infection","volume":"206","author":"Robinson","year":"2009","journal-title":"J. Exp. Med."}],"container-title":["Vaccines"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-393X\/14\/7\/557\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,6,25]],"date-time":"2026-06-25T09:33:59Z","timestamp":1782380039000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-393X\/14\/7\/557"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6,25]]},"references-count":32,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2026,7]]}},"alternative-id":["vaccines14070557"],"URL":"https:\/\/doi.org\/10.3390\/vaccines14070557","relation":{},"ISSN":["2076-393X"],"issn-type":[{"value":"2076-393X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,25]]}}}