{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,7]],"date-time":"2026-10-07T08:40:21Z","timestamp":1791362421055,"version":"4.3.1"},"reference-count":51,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T00:00:00Z","timestamp":1760054400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100016077","name":"European Union","doi-asserted-by":"publisher","award":["101191725"],"award-info":[{"award-number":["101191725"]}],"id":[{"id":"10.13039\/100016077","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Viruses"],"abstract":"<jats:p>The genus Orthoflavivirus (family Flaviviridae) comprises several important pathogens that are widespread across the globe, often co-circulating in many regions. In Austria, the closely related mosquito-borne West Nile (WN) and Usutu (USU) viruses have been detected since the early 2000s. Orthoflavivirus-neutralizing antibodies primarily target the major envelope protein E. However, due to their antigenic relationship, recurring contacts with different orthoflaviviruses can lead to the induction of broadly cross-reactive E-specific antibodies. These can pose a problem in the diagnosis and differentiation of orthoflavivirus infections. Therefore, we established immunological assays based on the non-structural protein 1 (NS1) to differentiate infections caused by WN and USU viruses. The NS1 protein is secreted during acute infection, and NS1-specific antibodies have been reported to be less cross-reactive than those against E. Using sera from individuals with a confirmed WN or USU virus infection, it was possible to distinguish between the two virus infections with high accuracy, specifically when IgM and IgG results were combined.<\/jats:p>","DOI":"10.3390\/v17101357","type":"journal-article","created":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T14:50:16Z","timestamp":1760107816000},"page":"1357","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Differentiation of West Nile and Usutu Virus Infections by Antibodies Directed to the Non-Structural Protein 1"],"prefix":"10.3390","volume":"17","author":[{"given":"Lena","family":"Ro\u00dfbacher","sequence":"first","affiliation":[{"name":"Center for Virology, Medical University of Vienna, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Samuel","family":"Taschler","sequence":"additional","affiliation":[{"name":"Center for Virology, Medical University of Vienna, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Elena","family":"Cecchettin","sequence":"additional","affiliation":[{"name":"Center for Virology, Medical University of Vienna, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Amelie","family":"Popovitsch","sequence":"additional","affiliation":[{"name":"Center for Virology, Medical University of Vienna, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stephan W.","family":"Aberle","sequence":"additional","affiliation":[{"name":"Center for Virology, Medical University of Vienna, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1197-3935","authenticated-orcid":false,"given":"Judith H.","family":"Aberle","sequence":"additional","affiliation":[{"name":"Center for Virology, Medical University of Vienna, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3891-7335","authenticated-orcid":false,"given":"Iris","family":"Medits-Weiss","sequence":"additional","affiliation":[{"name":"Center for Virology, Medical University of Vienna, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1902-8674","authenticated-orcid":false,"given":"Karin","family":"Stiasny","sequence":"additional","affiliation":[{"name":"Center for Virology, Medical University of Vienna, 1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,10,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"37","DOI":"10.1099\/0022-1317-70-1-37","article-title":"Antigenic relationships between flaviviruses as determined by cross-neutralization tests with polyclonal antisera","volume":"70","author":"Calisher","year":"1989","journal-title":"J. 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