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<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ali="http://www.niso.org/schemas/ali/1.0/" article-type="research-article" dtd-version="1.2" xml:lang="en"><front><journal-meta><journal-id journal-id-type="publisher-id">Morphology</journal-id><journal-title-group><journal-title xml:lang="en">Morphology</journal-title><trans-title-group xml:lang="ru"><trans-title>Морфология</trans-title></trans-title-group></journal-title-group><issn publication-format="print">1026-3543</issn><issn publication-format="electronic">2949-2556</issn><publisher><publisher-name xml:lang="en">Eco-Vector</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="publisher-id">678937</article-id><article-id pub-id-type="doi">10.17816/morph.678937</article-id><article-id pub-id-type="edn">EJGJDN</article-id><article-categories><subj-group subj-group-type="toc-heading" xml:lang="en"><subject>Original Study Articles</subject></subj-group><subj-group subj-group-type="toc-heading" xml:lang="ru"><subject>Оригинальные исследования</subject></subj-group><subj-group subj-group-type="article-type"><subject>Research Article</subject></subj-group></article-categories><title-group><article-title xml:lang="en">Ultrastructural organization and virion production in Vero E6 cell line under infection with the Delta and Omicron SARS-CoV-2 genovariants</article-title><trans-title-group xml:lang="ru"><trans-title>Ультраструктурная организация и продукция вирионов в клетках линии Vero E6 в условиях инфицирования геновариантами Delta и Omicron SARS-CoV-2</trans-title></trans-title-group><trans-title-group xml:lang="zh"><trans-title>在SARS-CoV-2 Delta与Omicron基因变异株感染条件下Vero E6细胞中病毒颗粒的超微结构组织与生成特征</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0009-0006-8655-6713</contrib-id><name-alternatives><name xml:lang="en"><surname>Spiridonova</surname><given-names>Ekaterina V.</given-names></name><name xml:lang="ru"><surname>Спиридонова</surname><given-names>Екатерина Викторовна</given-names></name><name xml:lang="zh"><surname>Spiridonova</surname><given-names>Ekaterina V.</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><email>spiridonova_ev@vector.nsc.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0009-0003-5165-5357</contrib-id><name-alternatives><name xml:lang="en"><surname>Emtsova</surname><given-names>Ksenia F.</given-names></name><name xml:lang="ru"><surname>Емцова</surname><given-names>Ксения Федоровна</given-names></name><name xml:lang="zh"><surname>Emtsova</surname><given-names>Ksenia F.</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><email>emtsova_kf@vector.nsc.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-2028-6099</contrib-id><contrib-id contrib-id-type="spin">8454-9741</contrib-id><name-alternatives><name xml:lang="en"><surname>Omigov</surname><given-names>Vladimir V.</given-names></name><name xml:lang="ru"><surname>Омигов</surname><given-names>Владимир Вилорьевич</given-names></name><name xml:lang="zh"><surname>Omigov</surname><given-names>Vladimir V.</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>MD<bold>, </bold>Cand. Sci. (Medicine)</p></bio><bio xml:lang="ru"><p>кандидат медицинских наук</p></bio><bio xml:lang="zh"><p>MD<bold>, </bold>Cand. Sci. (Medicine)</p></bio><email>omigov_vv@vector.nsc.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-6746-8092</contrib-id><name-alternatives><name xml:lang="en"><surname>Taranov</surname><given-names>Oleg S.</given-names></name><name xml:lang="ru"><surname>Таранов</surname><given-names>Олег Святославович</given-names></name><name xml:lang="zh"><surname>Taranov</surname><given-names>Oleg S.</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><email>taranov@vector.nsc.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0001-7048-2357</contrib-id><name-alternatives><name xml:lang="en"><surname>Moiseeva</surname><given-names>Anastasia A.</given-names></name><name xml:lang="ru"><surname>Моисеева</surname><given-names>Анастасия Алексеевна</given-names></name><name xml:lang="zh"><surname>Moiseeva</surname><given-names>Anastasia A.</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><email>chalaya_aa@vector.nsc.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0009-0007-8106-7037</contrib-id><contrib-id contrib-id-type="spin">8890-7214</contrib-id><name-alternatives><name xml:lang="en"><surname>Danilenko</surname><given-names>Elena I.</given-names></name><name xml:lang="ru"><surname>Даниленко</surname><given-names>Елена Игоревна</given-names></name><name xml:lang="zh"><surname>Danilenko</surname><given-names>Elena I.</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><email>danilenko_ei@vector.nsc.ru</email><xref ref-type="aff" rid="aff1"/></contrib></contrib-group><aff-alternatives id="aff1"><aff><institution xml:lang="en">State Research Center of Virology and Biotechnology “Vector”</institution></aff><aff><institution xml:lang="ru">Государственный научный центр вирусологии и биотехнологии «Вектор» Роспотребнадзора</institution></aff><aff><institution xml:lang="zh">State Research Center of Virology and Biotechnology “Vector”</institution></aff></aff-alternatives><pub-date date-type="preprint" iso-8601-date="2025-10-20" publication-format="electronic"><day>20</day><month>10</month><year>2025</year></pub-date><pub-date date-type="pub" iso-8601-date="2025-12-25" publication-format="electronic"><day>25</day><month>12</month><year>2025</year></pub-date><volume>164</volume><issue>1</issue><issue-title xml:lang="en"/><issue-title xml:lang="ru"/><issue-title xml:lang="zh"/><fpage>37</fpage><lpage>46</lpage><history><date date-type="received" iso-8601-date="2025-04-28"><day>28</day><month>04</month><year>2025</year></date><date date-type="accepted" iso-8601-date="2025-06-18"><day>18</day><month>06</month><year>2025</year></date></history><permissions><copyright-statement xml:lang="en">Copyright ©; 2025, Eco-Vector</copyright-statement><copyright-statement xml:lang="ru">Copyright ©; 2025, Эко-Вектор</copyright-statement><copyright-statement xml:lang="zh">Copyright ©; 2025,</copyright-statement><copyright-year>2025</copyright-year><copyright-holder xml:lang="en">Eco-Vector</copyright-holder><copyright-holder xml:lang="ru">Эко-Вектор</copyright-holder><ali:free_to_read xmlns:ali="http://www.niso.org/schemas/ali/1.0/" start_date="2028-12-25"/><license><ali:license_ref xmlns:ali="http://www.niso.org/schemas/ali/1.0/">https://eco-vector.com/for_authors.php#07</ali:license_ref></license></permissions><self-uri xlink:href="https://j-morphology.com/1026-3543/article/view/678937">https://j-morphology.com/1026-3543/article/view/678937</self-uri><abstract xml:lang="en"><p><bold>BACKGROUND</bold><bold>: </bold>The emergence of the coronavirus (SARS-CoV-2) caused a pandemic that led to an increase in morbidity and mortality among infected individuals. The SARS-CoV-2 variants circulating during that period, including Delta, were characterized by a broad spectrum of pathological effects at both the tissue and cellular levels. In 2025, the Omicron variant predominates, producing milder forms of respiratory conditions.</p> <p>Among the key research questions related to SARS-CoV-2, considerable attention has been devoted to its pathogenicity, which is characterized by high virulence and the ability to induce systemic pathological processes.</p> <p>Transmission electron microscopy is used to visualize virus–cell receptor interactions and to study the destructive impact of the pathogen on host cells. The findings of such studies form the basis for understanding the course and pathogenesis of the disease and contribute to vaccine development.</p> <p><bold>AIM</bold><bold>: </bold>The work aimed to investigate SARS-CoV-2 virion reproduction and the trends of cytopathic effects in Vero E6 cell culture infected with Delta and Omicron variants.</p> <p><bold>METHODS</bold><bold>: </bold>Ultrastructural analysis was performed on Vero E6 cell cultures infected with the Delta and Omicron SARS-CoV-2 variants. Infected cell cultures were fixed at three time points: 6, 18, and 24 hours after viral inoculation.</p> <p><bold>RESULTS</bold><bold>: </bold>Most samples in both groups (Delta and Omicron) retained near-normal morphology 6 hours post-inoculation and exhibited numerous transport vesicles. At 18 hours, Delta and Omicron groups showed similar morphological changes, including vacuolization of the endoplasmic reticulum and Golgi complex. The Omicron group demonstrated altered mitochondrial morphology. Marked destructive changes were observed 24 hours post-inoculation. Both groups displayed cytoplasmic condensation, extensive organelle vacuolization, and numerous vesicles containing viral particles. Analysis of virion reproduction trends revealed an increase in viral particle numbers at 18 hours, followed by a decline in viral virion replication by 24 hours.</p> <p><bold>CONCLUSION</bold><bold>: </bold>The study suggests similar mechanisms of cytopathic pattern formation in Vero E6 cells infected with the Delta and Omicron SARS-CoV-2 variants, along with active virion reproduction in cell culture between 6 and 18 hours post-infection.</p></abstract><trans-abstract xml:lang="ru"><p><bold>Обоснование. </bold>Появление коронавируса (SARS-CoV-2) вызвало пандемию, повлёкшую рост заболеваемости и высокий процент смертности инфицированных. Циркулировавшие в тот период штаммы SARS-CoV-2, включая вариант Delta, характеризовались широким спектром патологических эффектов на тканевом и клеточном уровнях. В 2025 году преобладает штамм Omicron, вызывающий менее яркие формы патологии дыхательной системы.</p> <p>Среди основных научных вопросов, связанных с изучением SARS-CoV-2, большое внимание уделяется его патогенности, характеризующейся высокой вирулентностью и способностью вызывать системные патологические процессы.</p> <p>Для визуализации взаимодействия вируса с рецепторами клеток, а также при изучении деструктивного воздействия патогенного агента на клетки хозяина, используют трансмиссионную электронную микроскопию. Результаты таких исследований лежат в основе понимания течения болезни и её патогенеза, а также способствуют разработке вакцин.</p> <p><bold>Цель работы</bold> — исследовать репродукцию вирионов SARS-CoV-2 и динамику цитопатических эффектов на модели клеточной культуры Vero E6 при заражении штаммами Delta и Omicron.</p> <p><bold>Методы. </bold>Исследование ультраструктурных изменений проводили на клеточной культуре Vero E6, которую инфицировали штаммами Delta и Omicron SARS-CoV-2. Инфицированные клеточные культуры фиксировали в трёх временных точках — 6, 18 и 24 часа после инокуляции вируса.</p> <p><bold>Результаты. </bold>Большинство образцов в обеих группах (Delta и Omicron) через 6 часов после инокуляции вируса сохраняют близкую к норме морфологическую картину и характеризуются формированием множества транспортных везикул. На стадии 18 часов выявлены схожие морфологические признаки в группах Delta и Omicron — вакуолизация синтетического комплекса эндоплазматической сети и комплекса Гольджи. При этом Omicron-группа отличается изменённой морфологией митохондрий. Существенные деструктивные изменения наблюдали спустя 24 часа после введения вируса. Для обеих групп характерны уплотнения гиалоплазмы, обширная вакуолизация органелл, а также часто встречающиеся везикулы, содержащие вирусные частицы. Изучение динамики репродукции частиц в каждой группе выявило увеличение их количества во временной точке 18 часов, с последующим снижением уровня репликации вирионов вируса к 24 часам наблюдения.</p> <p><bold>Заключение.</bold> На основании проведённого исследования сделано предположение о схожих механизмах формирования цитопатических паттернов в клетках Vero E6, вызванных штаммами Delta и Omicron SARS-CoV-2, а также об активной репродукции вирионов в клеточной культуре в период между 6 и 18 часами после инфицирования.</p></trans-abstract><trans-abstract xml:lang="zh"><p>论证。新型冠状病毒（SARS-CoV-2）的出现引发全球性大流行，导致发病率上升并造成较高的病死率。在该时期流行的SARS-CoV-2毒株，包括Delta变异株，在组织和细胞水平上表现出广泛的病理效应。至2025年，Omicron变异株成为主要流行株，其引起的呼吸系统病变表现相对较轻。</p> <p>在与SARS-CoV-2研究相关的主要科学问题中，其致病性受到广泛关注，其特征在于高毒力及引发全身性病理过程的能力。</p> <p>为可视化病毒与宿主细胞受体的相互作用并研究其破坏效应，常采用透射电子显微镜技术。此类研究结果为理解疾病的病程和发病机制提供形态学基础，也为疫苗研制提供重要参考。</p> <p>目的：研究SARS-CoV-2在Vero E6细胞培养模型中感染Delta和Omicron变异株时的病毒颗粒复制及细胞病变效应的动态变化。</p> <p>方法：在Vero E6细胞培养体系中进行超微结构变化的研究，细胞分别感染SARS-CoV-2的Delta和Omicron变异株。感染后的细胞培养物在病毒接种后6小时、18小时和24小时三个时间点进行固定处理。</p> <p>结果。病毒接种后6小时，两组（Delta与Omicron）的大多数样本保持接近正常的细胞形态，并形成大量运输囊泡。在感染后18小时阶段，在Delta组和Omicron组中均观察到相似的形态学特征——合成系统的内质网和高尔基体出现空泡化。与此同时，Omicron组表现出线粒体形态的改变。在病毒接种后24小时，观察到显著的破坏性变化。两组均表现出胞质致密化、细胞器广泛空泡化，以及大量含有病毒颗粒的囊泡。对各组病毒颗粒复制动态的研究显示，在感染后18小时病毒颗粒数量增加，随后至24小时观察时病毒复制水平下降。</p> <p>结论。基于本研究结果，推测SARS-CoV-2 Delta与Omicron变异株在Vero E6细胞中可诱发相似的细胞病变模式，其病毒颗粒在感染后6–18小时内处于活跃复制阶段。</p></trans-abstract><kwd-group xml:lang="en"><kwd>Delta SARS-CoV-2</kwd><kwd>Omicron SARS-CoV-2</kwd><kwd>SARS-CoV-2</kwd><kwd>Vero E6</kwd></kwd-group><kwd-group xml:lang="ru"><kwd>Delta SARS-CoV-2</kwd><kwd>Omicron SARS-CoV-2</kwd><kwd>SARS-CoV-2</kwd><kwd>Vero E6</kwd></kwd-group><kwd-group xml:lang="zh"><kwd>Delta SARS-CoV-2</kwd><kwd>Omicron SARS-CoV-2</kwd><kwd>SARS-CoV-2</kwd><kwd>Vero E6</kwd></kwd-group><funding-group><award-group><funding-source><institution-wrap><institution xml:lang="ru">Правительство РФ, госбюджет</institution></institution-wrap><institution-wrap><institution xml:lang="en">Government of the Russian Federation, state budget</institution></institution-wrap></funding-source></award-group></funding-group></article-meta></front><body></body><back><ref-list><ref id="B1"><label>1.</label><mixed-citation>Bevova MR, Netesov SV, Aulchenko YS. 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