{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,7,23]],"date-time":"2026-07-23T14:01:58Z","timestamp":1784815318816,"version":"3.55.0"},"posted":{"date-parts":[[2026,7,18]]},"group-title":"Microbiology","reference-count":58,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,7,18]],"date-time":"2026-07-18T00:00:00Z","timestamp":1784332800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Swine Health Information Center","award":["25-020"],"award-info":[{"award-number":["25-020"]}]},{"name":"United States Department of Agriculture (USDA) National Institute of Food and Agriculture","award":["2025-39601-44639"],"award-info":[{"award-number":["2025-39601-44639"]}]},{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"crossref","award":["P30 CA016058"],"award-info":[{"award-number":["P30 CA016058"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,7,18]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                <jats:p>Since 2024, highly pathogenic influenza A(H5N1) viruses have spread extensively among U.S. dairy cattle, where they replicate efficiently in the mammary gland and are shed at high titers in milk. To directly assess susceptibility of commercial swine populations to bovine-derived H5N1 virus, lactating sows with prior influenza virus vaccination histories representative of U.S. commercial swine production systems were inoculated via the intramammary route and co-housed with their 1-week-old piglets to evaluate disease outcomes, viral replication, and potential for vertical transmission. Intramammary inoculation of lactating sows resulted in sustained viral RNA shedding in milk, while piglets exhibited sporadic oral viral RNA positivity that mirrored viral kinetics in milk. Lesions in mammary tissue and viral antigen staining, as well as development of neutralizing antibody responses and changes in milk color and consistency, further confirmed infection in the sows. Despite these molecular findings, none of the animals developed overt clinical disease, and respiratory involvement was not noted during the study period. Collectively, we demonstrate that intramammary exposure results in productive influenza A(H5N1) virus infection in lactating sows despite their vaccination histories, indicating the potential threat of viral spillover into commercial swine populations. The clinically inapparent nature of infection presents a risk of subclinical spread and underscores the importance of expanding viral surveillance to swine.<\/jats:p>","DOI":"10.64898\/2026.07.18.739312","type":"posted-content","created":{"date-parts":[[2026,7,19]],"date-time":"2026-07-19T17:35:16Z","timestamp":1784482516000},"source":"Crossref","is-referenced-by-count":0,"title":["Bovine-derived H5N1 influenza virus efficiently infects lactating swine via the mammary gland"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-6585-1444","authenticated-orcid":false,"given":"Min","family":"Liu","sequence":"first","affiliation":[{"name":"Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA"},{"name":"Infectious Diseases Institute, The Ohio State University, Columbus, OH, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0004-7737-4040","authenticated-orcid":false,"given":"Natalie N.","family":"Chillson","sequence":"additional","affiliation":[{"name":"Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Emma A.","family":"Martin","sequence":"additional","affiliation":[{"name":"Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-3033-7623","authenticated-orcid":false,"given":"Hannah J.","family":"Cochran","sequence":"additional","affiliation":[{"name":"Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4226-7339","authenticated-orcid":false,"given":"Janice Y.","family":"Park","sequence":"additional","affiliation":[{"name":"Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Brady","family":"O\u2019Boyle","sequence":"additional","affiliation":[{"name":"Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6363-0999","authenticated-orcid":false,"given":"Devra","family":"Huey","sequence":"additional","affiliation":[{"name":"Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA"},{"name":"Infectious Diseases Institute, The Ohio State University, Columbus, OH, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kara N.","family":"Corps","sequence":"additional","affiliation":[{"name":"Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA"},{"name":"Infectious Diseases Institute, The Ohio State University, Columbus, OH, USA"},{"name":"Comparative Pathology & Digital Imaging Shared Resource, The Ohio State University Comprehensive Cancer Center, Columbus, OH, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0738-8453","authenticated-orcid":false,"given":"Andrew S.","family":"Bowman","sequence":"additional","affiliation":[{"name":"Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4101-2705","authenticated-orcid":false,"given":"Cody J.","family":"Warren","sequence":"additional","affiliation":[{"name":"Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA"},{"name":"Infectious Diseases Institute, The Ohio State University, Columbus, OH, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026072306151633000_2026.07.18.739312v1.1","doi-asserted-by":"publisher","DOI":"10.1016\/j.virol.2023.109860"},{"key":"2026072306151633000_2026.07.18.739312v1.2","unstructured":"Confirmed Pathogenic Avian Flu in Commercial & Backyard Flocks | APHIS. https:\/\/www.aphis.usda.gov\/livestock-poultry-disease\/avian\/avian-influenza\/hpai-detections\/commercial-backyard-flocks."},{"key":"2026072306151633000_2026.07.18.739312v1.3","doi-asserted-by":"publisher","DOI":"10.1128\/mbio.02542-24"},{"key":"2026072306151633000_2026.07.18.739312v1.4","doi-asserted-by":"publisher","DOI":"10.1126\/science.adq0900"},{"key":"2026072306151633000_2026.07.18.739312v1.5","unstructured":"Timing and molecular characterisation of the transmission to cattle of H5N1 influenza A virus genotype D1.1, clade 2.3.4.4b - Influenza virus \/ H5N1-global. 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