{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T04:27:51Z","timestamp":1787632071302,"version":"build-2736575974"},"reference-count":50,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,8,23]],"date-time":"2026-08-23T00:00:00Z","timestamp":1787443200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100012166","name":"National Key R & D Program of China","doi-asserted-by":"crossref","award":["2025YFE0209800"],"award-info":[{"award-number":["2025YFE0209800"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100012166","name":"National Key R & D Program of China","doi-asserted-by":"crossref","award":["2022YFF0710500"],"award-info":[{"award-number":["2022YFF0710500"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"crossref"}]},{"name":"Open Project of GuoTai (Taizhou) Center of Technology Innovation for Veterinary Biologicals","award":["GTKF (25-002; 23-003)"],"award-info":[{"award-number":["GTKF (25-002; 23-003)"]}]},{"name":"Postgraduate Research & Practice Innovation Program of Jiangsu Province","award":["SJCX24_0242"],"award-info":[{"award-number":["SJCX24_0242"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vet. Sci.","Veterinary Sciences"],"abstract":"<jats:p>Conventional needle-based vaccination may cause tissue injury and increase the risk of cross-contamination between animals. This study evaluated the immunological effects of delivering an inactivated porcine circovirus type 2 (PCV2) vaccine using a needle-free jet injection system compared with needle injection in pigs. Immune responses were assessed using enzyme-linked immunosorbent assay (ELISA) for PCV2-specific antibody levels on days 7, 14, and 28 post-vaccination. Cellular architecture at injection sites and differential gene expression were analyzed using immunohistochemistry and transcriptome sequencing. Results showed that pigs receiving needle-free vaccination at 0.50 mL and 0.75 mL injection volumes exhibited higher PCV2-specific antibody responses than pigs receiving 1.0 mL needle injection. Needle-free vaccination also preserved dermal collagen fiber architecture, altered antigen-presenting cell distribution, and was associated with distinct activation of immune-related pathways, particularly those involved in leukocyte migration and cytokine-cytokine receptor interactions. These findings indicate that needle-free vaccination was associated with distinct PCV2-specific antibody responses and local immune microenvironment changes, supporting its potential as an alternative vaccine delivery strategy for swine PCV2 vaccination.<\/jats:p>","DOI":"10.3390\/vetsci13090854","type":"journal-article","created":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T13:20:43Z","timestamp":1787577643000},"page":"854","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Enhanced Immunogenicity and Distinct Local Tissue Responses of Porcine Circovirus Type 2 Vaccination in Pigs Using a Needle-Free Jet Injection System"],"prefix":"10.3390","volume":"13","author":[{"given":"Zihui","family":"Jiao","sequence":"first","affiliation":[{"name":"College of Veterinary Medicine, Nanjing Agricultural University, No. 1 Weigang, Nanjing 210095, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-2516-1627","authenticated-orcid":false,"given":"Haiyan","family":"Wang","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, Nanjing Agricultural University, No. 1 Weigang, Nanjing 210095, China"},{"name":"GuoTai (Taizhou) Center of Technology Innovation for Veterinary Biologicals,  Taizhou 225300, China"},{"name":"National Research Center of Engineering and Technology for Veterinary Biologicals, Institute of Veterinary Immunology and Engineering, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiangfei","family":"Meng","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, Nanjing Agricultural University, No. 1 Weigang, Nanjing 210095, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mingfa","family":"Yang","sequence":"additional","affiliation":[{"name":"State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chunyuan","family":"Dai","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, Nanjing Agricultural University, No. 1 Weigang, Nanjing 210095, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhaoxuan","family":"Zhu","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, Nanjing Agricultural University, No. 1 Weigang, Nanjing 210095, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0004-9780-4570","authenticated-orcid":false,"given":"Xinzi","family":"Guo","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, Nanjing Agricultural University, No. 1 Weigang, Nanjing 210095, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ping","family":"Yang","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, Nanjing Agricultural University, No. 1 Weigang, Nanjing 210095, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yu","family":"Lu","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, Nanjing Agricultural University, No. 1 Weigang, Nanjing 210095, China"},{"name":"GuoTai (Taizhou) Center of Technology Innovation for Veterinary Biologicals,  Taizhou 225300, China"},{"name":"National Research Center of Engineering and Technology for Veterinary Biologicals, Institute of Veterinary Immunology and Engineering, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"211","DOI":"10.1038\/nri1310","article-title":"Immune surveillance in the skin: Mechanisms and clinical consequences","volume":"4","author":"Kupper","year":"2004","journal-title":"Nat. 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