{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T17:11:04Z","timestamp":1784135464719,"version":"3.55.0"},"reference-count":19,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T00:00:00Z","timestamp":1784073600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Vet. Sci."],"abstract":"<jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>To address practical application and production demands, this study aims to develop a Porcine epidemic diarrhea (PED) subunit vaccine with high expression efficiency and immunogenicity, using molecular biology and structural biology approaches.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      Based on the established immunostimulatory properties of flagellin, a recombinant fusion protein was constructed by linking the\n                      <jats:italic>Salmonella choleraesuis<\/jats:italic>\n                      flagellin mutant FliC\n                      <jats:sub>L3A<\/jats:sub>\n                      to the core neutralizing epitope (COE) of the spike protein of porcine epidemic diarrhea virus (PEDV). The target protein was expressed using a CHO-S cell expression system and subsequently formulated into a subunit vaccine with adjuvant 201. Immunogenicity was systematically evaluated in a mouse model by measuring serum levels of PEDV-specific IgG, IgA, and IgM antibodies, as well as the cytokines IFN-\n                      <jats:italic>\u03b3<\/jats:italic>\n                      and IL-4.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Structural prediction of the FliC\n                      <jats:sub>L3A<\/jats:sub>\n                      -COE fusion protein by AlphaFold2 indicated that the protein can spontaneously assemble into a bouquet-like multimeric structure. Following condition optimization, a CHO-S cell expression system with a transfection efficiency of approximately 80% was successfully established. Post-immunization ELISA results demonstrated that the level of PEDV-specific IgG increased progressively with the number of immunizations and reached a peak after the second booster immunization; IgA levels peaked after the first booster immunization but declined following the second booster; IgM levels reached their maximum after the primary immunization and decreased significantly with subsequent boosters. The expression trends of IFN-\n                      <jats:italic>\u03b3<\/jats:italic>\n                      and IL-4 were consistent, both continuously increasing with each booster immunization. Compared with the commercial vaccine, the FliC\n                      <jats:sub>L3A<\/jats:sub>\n                      -COE subunit vaccine induced lower levels of IFN-\n                      <jats:italic>\u03b3<\/jats:italic>\n                      ; the levels of IgG, IgA, IgM, and IL-4 showed no significant difference from those induced by the commercial vaccine.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>\n                      The FliC\n                      <jats:sub>L3A<\/jats:sub>\n                      -COE fusion protein induces PEDV-specific antibodies and elicits detectable immune responses in mice. Its immunogenicity profile in terms of antibody induction is generally similar to that of a commercial vaccine, although IFN-\n                      <jats:italic>\u03b3<\/jats:italic>\n                      responses were lower. These findings indicate that the fusion protein has certain immunostimulatory properties, but further optimization may be needed to improve its immune potency.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fvets.2026.1827170","type":"journal-article","created":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T17:00:21Z","timestamp":1784134821000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Construction of subunit vaccine by fusing Salmonella flagellin with neutralizing epitopes of porcine epidemic diarrhea virus"],"prefix":"10.3389","volume":"13","author":[{"given":"Xudong","family":"Gao","sequence":"first","affiliation":[{"name":"Animal Husbandry and Aquatic Research Center, Guangdong Haida Group Co., Ltd.","place":["Guangzhou, Guangdong, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuanfang","family":"Rao","sequence":"additional","affiliation":[{"name":"Animal Husbandry and Aquatic Research Center, Guangdong Haida Group Co., Ltd.","place":["Guangzhou, Guangdong, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aiqing","family":"Jia","sequence":"additional","affiliation":[{"name":"Animal Husbandry and Aquatic Research Center, Guangdong Haida Group Co., Ltd.","place":["Guangzhou, Guangdong, China"]},{"name":"Guangdong Provincial Key Laboratory of Pig Breeding and Disease Control Technology","place":["Guangzhou, Guangdong, China"]},{"name":"Guangdong Hairui Biotechnology Co., Ltd.","place":["Guangzhou, Guangdong, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Guiping","family":"Wang","sequence":"additional","affiliation":[{"name":"Animal Husbandry and Aquatic Research Center, Guangdong Haida Group Co., Ltd.","place":["Guangzhou, Guangdong, China"]},{"name":"Guangdong Provincial Key Laboratory of Pig Breeding and Disease Control Technology","place":["Guangzhou, Guangdong, China"]},{"name":"Guangdong Hairui Biotechnology Co., Ltd.","place":["Guangzhou, Guangdong, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jinming","family":"Cui","sequence":"additional","affiliation":[{"name":"Animal Husbandry and Aquatic Research Center, Guangdong Haida Group Co., Ltd.","place":["Guangzhou, Guangdong, China"]},{"name":"Guangdong Provincial Key Laboratory of Pig Breeding and Disease Control Technology","place":["Guangzhou, Guangdong, China"]},{"name":"Guangdong Hairui Biotechnology Co., Ltd.","place":["Guangzhou, Guangdong, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,7,15]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"243","DOI":"10.1007\/bf01317606","article-title":"A new coronavirus-like particle associated 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Virus estimated to have killed 7 million-plus pigs","volume":"245","author":"Cima","year":"2014","journal-title":"J Am Vet Med Assoc"},{"key":"ref12","doi-asserted-by":"publisher","first-page":"355","DOI":"10.1292\/jvms.15-0446","article-title":"Epidemiology and vaccine of porcine epidemic diarrhea virus in China: a mini-review","volume":"78","author":"Sun","year":"2016","journal-title":"J Vet Med Sci"},{"key":"ref13","doi-asserted-by":"publisher","first-page":"e0130924","DOI":"10.1128\/jvi.01309-24","article-title":"Efficacy evaluation of a bivalent subunit vaccine against epidemic PEDV heterologous strains with low cross-protection","volume":"98","author":"Song","year":"2024","journal-title":"J Virol"},{"key":"ref14","doi-asserted-by":"publisher","first-page":"1381","DOI":"10.1016\/j.vaccine.2018.01.086","article-title":"PED subunit vaccine based on COE domain replacement of flagellin domain D3 improved specific humoral and mucosal immunity in mice","volume":"36","author":"Li","year":"2018","journal-title":"Vaccine"},{"key":"ref15","doi-asserted-by":"publisher","first-page":"4228","DOI":"10.1016\/j.vaccine.2018.05.124","article-title":"A flagellin-adjuvanted PED subunit vaccine improved protective efficiency against PEDV variant challenge in pigs","volume":"36","author":"Li","year":"2018","journal-title":"Vaccine"},{"key":"ref16","doi-asserted-by":"publisher","first-page":"2152","DOI":"10.3389\/fimmu.2020.02152","article-title":"Plant-derived trimeric CO-26K-equivalent epitope induced neutralizing antibodies against porcine epidemic diarrhea virus","volume":"11","author":"Ho","year":"2020","journal-title":"Front Immunol"},{"key":"ref17","doi-asserted-by":"publisher","first-page":"1386136","DOI":"10.3389\/fmicb.2024.1386136","article-title":"Spike 1 trimer, a nanoparticle vaccine against porcine epidemic diarrhea virus induces protective immunity challenge in piglets","volume":"15","author":"Li","year":"2024","journal-title":"Front Microbiol"},{"key":"ref18","doi-asserted-by":"publisher","first-page":"139","DOI":"10.3390\/vaccines12020139","article-title":"Advancing PEDV vaccination: comparison between inactivated and flagellin N-terminus-adjuvanted subunit vaccines","volume":"12","author":"Murtaza","year":"2024","journal-title":"Vaccine"},{"key":"ref19","doi-asserted-by":"publisher","first-page":"514","DOI":"10.1038\/cmi.2015.33","article-title":"Activation of NLRC4 downregulates TLR5-mediated antibody immune responses against flagellin","volume":"13","author":"Li","year":"2016","journal-title":"Cell Mol Immunol"}],"container-title":["Frontiers in Veterinary Science"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fvets.2026.1827170\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T17:00:22Z","timestamp":1784134822000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fvets.2026.1827170\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,15]]},"references-count":19,"alternative-id":["10.3389\/fvets.2026.1827170"],"URL":"https:\/\/doi.org\/10.3389\/fvets.2026.1827170","relation":{},"ISSN":["2297-1769"],"issn-type":[{"value":"2297-1769","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,15]]},"article-number":"1827170"}}