{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,3]],"date-time":"2026-08-03T18:56:12Z","timestamp":1785783372631,"version":"3.56.0"},"reference-count":39,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,8,26]],"date-time":"2025-08-26T00:00:00Z","timestamp":1756166400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100004084","name":"Korea Science and Engineering Foundation","doi-asserted-by":"publisher","award":["No. 2020R1I1A1A01054539"],"award-info":[{"award-number":["No. 2020R1I1A1A01054539"]}],"id":[{"id":"10.13039\/501100004084","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"publisher","award":["NFR-2019R1A6A1A03032869"],"award-info":[{"award-number":["NFR-2019R1A6A1A03032869"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Microbiol."],"abstract":"<jats:sec><jats:title>Introduction<\/jats:title><jats:p>Pediatric isolates of SARS-CoV-2 remain underrepresented in virologic studies, despite their importance for understanding viral diversity and therapeutic responses.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Nasal swab and saliva samples were collected from pediatric COVID-19 patients. Viral isolation was attempted in Vero cells through five blind passages. Replication was assessed by digital RT-PCR, while cytopathic effects were observed microscopically. Genomic sequencing was conducted using next-generation sequencing, and antiviral activity was evaluated for Remdesivir, Molnupiravir, and Nirmatrelvir.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>A SARS-CoV-2 strain, designated N15, was successfully isolated from a pediatric nasal swab. The isolate replicated efficiently in Vero cells with kinetics comparable to B.1 and B.1.1.529 lineages. Cytopathic effects appeared within 48 h post-infection, marked by aggregates of dead cells. Genomic analysis classified N15 within lineage 19B, showing 99.9% similarity to the Wuhan-Hu-1 strain. Rare mutations were identified: N709S in the spike protein and T11M in the E protein. Antiviral testing revealed effective inhibition by Remdesivir, Molnupiravir, and Nirmatrelvir, with varying IC50 values across cell types.<\/jats:p><\/jats:sec><jats:sec><jats:title>Discussion<\/jats:title><jats:p>The pediatric N15 isolate represents a unique 19B lineage virus, retaining ancestral genomic features while harboring rare mutations. Its efficient replication and drug sensitivity underscore its value as a reference strain for comparative studies against circulating variants and for evaluating antiviral efficacy.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fmicb.2025.1654224","type":"journal-article","created":{"date-parts":[[2025,8,26]],"date-time":"2025-08-26T05:28:51Z","timestamp":1756186131000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["Isolation of a SARS-CoV-2 strain from pediatric patients in South Korea: biologic and genetic characterization"],"prefix":"10.3389","volume":"16","author":[{"given":"Hee Chun","family":"Chung","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sung Jae","family":"Kim","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Su Jin","family":"Hwang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sung Hoon","family":"Park","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kyoung Min","family":"Park","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hyeon Woo","family":"Chung","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Si Hwan","family":"Ko","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dong il","family":"Park","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jun-Yeop","family":"Shim","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Van Giap","family":"Nguyen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jae Myun","family":"Lee","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2025,8,26]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"113977","DOI":"10.1016\/j.biopha.2022.113977","article-title":"Mutations in SARS-CoV-2: Insights on structure, variants, vaccines, and biomedical interventions.","volume":"157","author":"Abulsoud","year":"2023","journal-title":"Biomed. 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