{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,23]],"date-time":"2026-05-23T05:06:49Z","timestamp":1779512809436,"version":"3.53.1"},"reference-count":25,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2026,5,21]],"date-time":"2026-05-21T00:00:00Z","timestamp":1779321600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Key Research and Development Program of China","award":["2022YFC2104801"],"award-info":[{"award-number":["2022YFC2104801"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Viruses"],"abstract":"<jats:p>Highly pathogenic avian influenza A (H7N9) remains a threat to poultry health and poses a zoonotic risk, highlighting the need for vaccine antigens capable of inducing both systemic and mucosal immunity. In this study, we evaluated X33CLS-H7, a clarified cell-lysate supernatant derived from glycoengineered Pichia pastoris expressing H7 hemagglutinin, in BALB\/c mice following intramuscular(i.m.) injection, nebulized inhalation, or intranasal instillation. H7 expression and hemagglutination activity were confirmed by Western blotting and hemagglutination assay, respectively. Serum HA7-specific IgG and IgA responses, hemagglutination inhibition(HI) activity, H7N9 pseudovirus neutralization, bronchoalveolar lavage fluid (BALF) antibodies, and safety readouts were assessed. After two i.m. immunizations, X33CLS-H7 induced the strongest systemic antibody responses, with an HI geometric mean titer of 1:1622 95% CI, 1:1108\u20131:2348 and a mean log10 NT50 of 4.62. Respiratory immunization also elicited antibody responses. After four doses, high-dose nebulized delivery produced the strongest responses among the respiratory delivery regimens, with serum IgG and IgA titers of 1.02 \u00d7 105 and 2.24 \u00d7 103, respectively, an endpoint HI GMT r of 1:457 95% CI, 1:211\u20131:971, and a mean log10 NT50 of 3.77 compared with 2.02 in saline controls. High-dose nebulized delivery also generated detectable HA7-specific IgG and IgA responses in bronchoalveolar lavage fluid. No overt local or systemic toxicity signals were observed under the tested conditions. These findings indicate that X33CLS-H7 retains HA7-associated antigenicity and can induce systemic and respiratory mucosal antibody responses, supporting its further evaluation as a simplified and scalable H7N9 vaccine antigen candidate.<\/jats:p>","DOI":"10.3390\/v18050579","type":"journal-article","created":{"date-parts":[[2026,5,21]],"date-time":"2026-05-21T15:02:27Z","timestamp":1779375747000},"page":"579","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Aerosol Inhalation of a Recombinant H7N9 Hemagglutinin Antigen Elicits Systemic and Mucosal Immune Responses in Mice"],"prefix":"10.3390","volume":"18","author":[{"given":"Zhuoran","family":"Hou","sequence":"first","affiliation":[{"name":"Tianjin Key Laboratory of Agricultural Animal Breeding and Healthy Husbandry, College of Animal Science and Veterinary Medicine, Tianjin Agricultural University, Tianjin 300392, China"},{"name":"National Key Laboratory of Advanced Biotechnology, Academy of Military Medical Sciences, Beijing 100071, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Han","family":"Wang","sequence":"additional","affiliation":[{"name":"National Key Laboratory of Advanced Biotechnology, Academy of Military Medical Sciences, Beijing 100071, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bin","family":"Zhang","sequence":"additional","affiliation":[{"name":"National Key Laboratory of Advanced Biotechnology, Academy of Military Medical Sciences, Beijing 100071, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ruixi","family":"Liu","sequence":"additional","affiliation":[{"name":"National Key Laboratory of Advanced Biotechnology, Academy of Military Medical Sciences, Beijing 100071, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuli","family":"Zhang","sequence":"additional","affiliation":[{"name":"National Key Laboratory of Advanced Biotechnology, Academy of Military Medical Sciences, Beijing 100071, China"},{"name":"College of Animal Science and Technology, Northwest A&F University, Yangling 712100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ye","family":"Yang","sequence":"additional","affiliation":[{"name":"National Key Laboratory of Advanced Biotechnology, Academy of Military Medical Sciences, Beijing 100071, China"},{"name":"School of Life Sciences and Medical Engineering, Anhui University, Hefei 230601, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jianxin","family":"Wu","sequence":"additional","affiliation":[{"name":"National Key Laboratory of Advanced Biotechnology, Academy of Military Medical Sciences, Beijing 100071, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xuchen","family":"Hou","sequence":"additional","affiliation":[{"name":"National Key Laboratory of Advanced Biotechnology, Academy of Military Medical Sciences, Beijing 100071, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiuguo","family":"Ge","sequence":"additional","affiliation":[{"name":"Tianjin Key Laboratory of Agricultural Animal Breeding and Healthy Husbandry, College of Animal Science and Veterinary Medicine, Tianjin Agricultural University, Tianjin 300392, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jun","family":"Wu","sequence":"additional","affiliation":[{"name":"National Key Laboratory of Advanced Biotechnology, Academy of Military Medical Sciences, Beijing 100071, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6655-1866","authenticated-orcid":false,"given":"Bo","family":"Liu","sequence":"additional","affiliation":[{"name":"National Key Laboratory of Advanced Biotechnology, Academy of Military Medical Sciences, Beijing 100071, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,5,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"47","DOI":"10.1038\/nrmicro.2017.118","article-title":"The Evolution of Seasonal Influenza Viruses","volume":"16","author":"Petrova","year":"2018","journal-title":"Nat. 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