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While RBD mutations are well characterized, mutations in the N-terminal domain (NTD) of the spike protein remain comparatively understudied despite their relevance to antibody recognition. This study investigates two phenotypically distinct SARS-CoV-2 mutants, which exhibited differences in plaque morphology on Vero cells. Whole-genome sequencing via Illumina identified a novel 12-nucleotide insertion in the spike NTD. This insertion induced a frameshift, introducing five new amino acids potentially altering viral behavior, receptor interactions, and antibody detection in ELISAs. The study further explores the pathogenicity of these variants in a hamster model. These findings underscore the importance of monitoring NTD mutations, which may contribute to immune evasion and influence therapeutic antibody efficacy, highlighting gaps in current research on SARS-CoV-2 evolution.<\/jats:p>","DOI":"10.3390\/v18030277","type":"journal-article","created":{"date-parts":[[2026,2,24]],"date-time":"2026-02-24T16:58:18Z","timestamp":1771952298000},"page":"277","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Insertion in the N-Terminal Domain of the SARS-CoV-2 Spike Glycoprotein Affects Antibody Recognition and Phenotypic Properties"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0406-0604","authenticated-orcid":false,"given":"Elena A.","family":"Ermolaeva","sequence":"first","affiliation":[{"name":"Chumakov FSC R&D IBP RAS (Institute of Poliomyelitis), 108819 Moscow, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3675-8361","authenticated-orcid":false,"given":"Anna N.","family":"Zyrina","sequence":"additional","affiliation":[{"name":"Chumakov FSC R&D IBP RAS (Institute of Poliomyelitis), 108819 Moscow, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dina I.","family":"Sirazova","sequence":"additional","affiliation":[{"name":"Chumakov FSC R&D IBP RAS (Institute of Poliomyelitis), 108819 Moscow, Russia"},{"name":"Institute for Translational Medicine and Biotechnology, First Moscow State Medical University (Sechenov University), 117418 Moscow, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alexander S.","family":"Lunin","sequence":"additional","affiliation":[{"name":"Chumakov FSC R&D IBP RAS (Institute of Poliomyelitis), 108819 Moscow, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-2342-1557","authenticated-orcid":false,"given":"Anton S.","family":"Motov","sequence":"additional","affiliation":[{"name":"Chumakov FSC R&D IBP RAS (Institute of Poliomyelitis), 108819 Moscow, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anastasia D.","family":"Chernavtseva","sequence":"additional","affiliation":[{"name":"Chumakov FSC R&D IBP RAS (Institute of Poliomyelitis), 108819 Moscow, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7441-1062","authenticated-orcid":false,"given":"Olga S.","family":"Gancharova","sequence":"additional","affiliation":[{"name":"Chumakov FSC R&D IBP RAS (Institute of Poliomyelitis), 108819 Moscow, Russia"},{"name":"Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3029-1035","authenticated-orcid":false,"given":"Liubov I.","family":"Kozlovskaya","sequence":"additional","affiliation":[{"name":"Chumakov FSC R&D IBP RAS (Institute of Poliomyelitis), 108819 Moscow, Russia"},{"name":"Institute for Translational Medicine and Biotechnology, First Moscow State Medical University (Sechenov University), 117418 Moscow, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anna A.","family":"Shishova","sequence":"additional","affiliation":[{"name":"Chumakov FSC R&D IBP RAS (Institute of Poliomyelitis), 108819 Moscow, Russia"},{"name":"Institute for Translational Medicine and Biotechnology, First Moscow State Medical University (Sechenov University), 117418 Moscow, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alexandra A.","family":"Siniugina","sequence":"additional","affiliation":[{"name":"Chumakov FSC R&D IBP RAS (Institute of Poliomyelitis), 108819 Moscow, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aydar A.","family":"Ishmukhametov","sequence":"additional","affiliation":[{"name":"Chumakov FSC R&D IBP RAS (Institute of Poliomyelitis), 108819 Moscow, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"141","DOI":"10.1038\/s41579-020-00459-7","article-title":"Characteristics of SARS-CoV-2 and COVID-19","volume":"19","author":"Hu","year":"2021","journal-title":"Nat. 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