<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE root>
<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">Journal of microbiology, epidemiology and immunobiology</journal-id><journal-title-group><journal-title xml:lang="en">Journal of microbiology, epidemiology and immunobiology</journal-title><trans-title-group xml:lang="ru"><trans-title>Журнал микробиологии, эпидемиологии и иммунобиологии</trans-title></trans-title-group></journal-title-group><issn publication-format="print">0372-9311</issn><issn publication-format="electronic">2686-7613</issn><publisher><publisher-name xml:lang="en">Central Research Institute for Epidemiology</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="publisher-id">18479</article-id><article-id pub-id-type="doi">10.36233/0372-9311-367</article-id><article-id pub-id-type="edn">tnzpid</article-id><article-categories><subj-group subj-group-type="toc-heading" xml:lang="en"><subject>ORIGINAL RESEARCHES</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">Comparative analysis of IgG levels in blood sera from patients with COVID-19, persons vaccinated by «Gam-COVID-Vac» and healthy donors before the pandemic</article-title><trans-title-group xml:lang="ru"><trans-title>Сравнительный анализ уровня IgG в сыворотках крови больных COVID-19, вакцинированных «Гам-КОВИД-Вак», и здоровых доноров до пандемии</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0003-3226-5989</contrib-id><name-alternatives><name xml:lang="en"><surname>Tarakanova</surname><given-names>Yulia N.</given-names></name><name xml:lang="ru"><surname>Тараканова</surname><given-names>Юлия Николаевна</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>Cand. Sci. (Biol.), Head, Laboratory of diagnostics of viral infections, Department of virology, I. Mechnikov Research Institute for Vaccines and Sera</p></bio><bio xml:lang="ru"><p>к.б.н., зав. лаб. диагностики вирусных инфекций отдела вирусологии НИИВС им. И.И. Мечникова</p></bio><email>ytarakanova@mail.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-7664-2945</contrib-id><name-alternatives><name xml:lang="en"><surname>Borisova</surname><given-names>Olga V.</given-names></name><name xml:lang="ru"><surname>Борисова</surname><given-names>Ольга Васильевна</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>Cand. Sci. (Chem.), Head, Laboratory of medical biotechnology, Department of virology, I. Mechnikov Research Institute for Vaccines and Sera</p></bio><bio xml:lang="ru"><p>к.х.н., зав. лаб. медицинской биотехнологии отдела вирусологии НИИВС им. И.И. Мечникова, Москва</p></bio><email>ytarakanova@mail.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-7397-6499</contrib-id><name-alternatives><name xml:lang="en"><surname>Dmitriev</surname><given-names>Dmitriy A.</given-names></name><name xml:lang="ru"><surname>Дмитриев</surname><given-names>Дмитрий Александрович</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>Cand. Sci. (Biol.), senior researcher, Laboratory of diagnostics of viral infections, Department of virology, I. Mechnikov Research Institute for Vaccines and Sera</p></bio><bio xml:lang="ru"><p>к.б.н., с.н.с. лаб. диагностики вирусных инфекций отдела вирусологии НИИВС им. И.И. Мечникова</p></bio><email>ytarakanova@mail.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0001-9579-7865</contrib-id><name-alternatives><name xml:lang="en"><surname>Lichutina</surname><given-names>Maria V.</given-names></name><name xml:lang="ru"><surname>Владимировна</surname><given-names>Мария Мария</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>junior researcher, Laboratory of diagnostics of viral infections, Department of virology, I. Mechnikov Research Institute for Vaccines and Sera</p></bio><bio xml:lang="ru"><p>м.н.с. лаб. диагностики вирусных инфекций отдела вирусологии НИИВС им. И.И. Мечникова</p></bio><email>ytarakanova@mail.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-1165-2712</contrib-id><name-alternatives><name xml:lang="en"><surname>Massino</surname><given-names>Yulia S.</given-names></name><name xml:lang="ru"><surname>Массино</surname><given-names>Юлия Сергеевна</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>Cand. Sci. (Biol.), senior researcher, Laboratory of diagnostics of viral infections, Department of virology, I. Mechnikov Research Institute for Vaccines and Sera</p></bio><bio xml:lang="ru"><p>к.б.н., с.н.с. лаб. диагностики вирусных инфекций отдела вирусологии НИИВС им. И.И. Мечникова</p></bio><email>ytarakanova@mail.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-6628-1576</contrib-id><name-alternatives><name xml:lang="en"><surname>Pechelyulko</surname><given-names>Anastasia A.</given-names></name><name xml:lang="ru"><surname>Печелюлько</surname><given-names>Анастасия Александровна</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>Cand. Sci. (Biol.), senior researcher, Laboratory of diagnostics of viral infections, Department of virology, I. Mechnikov Research Institute for Vaccines and Sera</p></bio><bio xml:lang="ru"><p>н.с. лаб. диагностики вирусных инфекций отдела вирусологии НИИВС им. И.И. Мечникова</p></bio><email>ytarakanova@mail.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-6621-236X</contrib-id><name-alternatives><name xml:lang="en"><surname>Segal</surname><given-names>Olga L.</given-names></name><name xml:lang="ru"><surname>Сегал</surname><given-names>Ольга Леонидовна</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>Cand. Sci. (Biol.), senior researcher, Laboratory of diagnostics of viral infections, Department of virology, I. Mechnikov Research Institute for Vaccines and Sera</p></bio><bio xml:lang="ru"><p>к.б.н., с.н.с. лаб. диагностики вирусных инфекций отдела вирусологии НИИВС им. И.И. Мечникова</p></bio><email>ytarakanova@mail.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><name-alternatives><name xml:lang="en"><surname>Yakovleva</surname><given-names>Dinora A.</given-names></name><name xml:lang="ru"><surname>Яковлева</surname><given-names>Динора Абдуллаевна</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>Cand. Sci. (Biol.), senior researcher, Laboratory of diagnostics of viral infections, Department of virology, I. Mechnikov Research Institute for Vaccines and Sera</p></bio><bio xml:lang="ru"><p>к.м.н., с.н.с. лаб. диагностики вирусных инфекций отдела вирусологии НИИВС им. И.И. Мечникова</p></bio><email>ytarakanova@mail.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-1132-3708</contrib-id><name-alternatives><name xml:lang="en"><surname>Dmitriev</surname><given-names>Alexander D.</given-names></name><name xml:lang="ru"><surname>Дмитриев</surname><given-names>Александр Дмитриевич</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>D. Sci. (Biol.), leading researcher, Laboratory of diagnostics of viral infections, Department of virology, I. Mechnikov Research Institute for Vaccines and Sera</p></bio><bio xml:lang="ru"><p>д.б.н., в.н.с. лаб. диагностики вирусных инфекций отдела вирусологии НИИВС им. И.И. Мечникова</p></bio><email>ytarakanova@mail.ru</email><xref ref-type="aff" rid="aff1"/></contrib></contrib-group><aff-alternatives id="aff1"><aff><institution xml:lang="en">I. Mechnikov Research Institute for Vaccines and Sera</institution></aff><aff><institution xml:lang="ru">Научно-исследовательский институт вакцин и сывороток имени И.И. Мечникова</institution></aff></aff-alternatives><pub-date date-type="pub" iso-8601-date="2023-11-22" publication-format="electronic"><day>22</day><month>11</month><year>2023</year></pub-date><volume>100</volume><issue>5</issue><issue-title xml:lang="en"/><issue-title xml:lang="ru"/><fpage>319</fpage><lpage>327</lpage><history><date date-type="received" iso-8601-date="2023-11-20"><day>20</day><month>11</month><year>2023</year></date></history><permissions><copyright-statement xml:lang="en">Copyright ©; 2023, Tarakanova Y.N., Borisova O.V., Dmitriev D.A., Lichutina M.V., Massino Y.S., Pechelyulko A.A., Segal O.L., Yakovleva D.A., Dmitriev A.D.</copyright-statement><copyright-statement xml:lang="ru">Copyright ©; 2023, Тараканова Ю.Н., Борисова О.В., Дмитриев Д.А., Владимировна М.М., Массино Ю.С., Печелюлько А.А., Сегал О.Л., Яковлева Д.А., Дмитриев А.Д.</copyright-statement><copyright-year>2023</copyright-year><copyright-holder xml:lang="en">Tarakanova Y.N., Borisova O.V., Dmitriev D.A., Lichutina M.V., Massino Y.S., Pechelyulko A.A., Segal O.L., Yakovleva D.A., Dmitriev A.D.</copyright-holder><copyright-holder xml:lang="ru">Тараканова Ю.Н., Борисова О.В., Дмитриев Д.А., Владимировна М.М., Массино Ю.С., Печелюлько А.А., Сегал О.Л., Яковлева Д.А., Дмитриев А.Д.</copyright-holder><ali:free_to_read xmlns:ali="http://www.niso.org/schemas/ali/1.0/"/><license><ali:license_ref xmlns:ali="http://www.niso.org/schemas/ali/1.0/">https://creativecommons.org/licenses/by/4.0</ali:license_ref></license></permissions><self-uri xlink:href="https://microbiol.crie.ru/jour/article/view/18479">https://microbiol.crie.ru/jour/article/view/18479</self-uri><abstract xml:lang="en"><p><bold>Introduction.</bold> Serum IgG measurement is used in the diagnosis and monitoring of many diseases. Therefore, it seems important to study the impact of coronavirus pandemic on IgG levels in population and the role of this parameter in COVID-19.</p> <p>The <bold>aim</bold> of this study was to compare mean IgG levels in sera obtained from 31 hospitalized COVID-19 patients, 30 healthy donors before pandemic and 34 donors vaccinated with «Sputnik V» (have not had COVID-19).</p> <p><bold>Materials and methods.</bold> Total IgG was quantitated by two enzyme immunoassays (EIAs): «IgG Total-ELISA-BEST» kit certificated in Russia and homemade competitive EIA utilizing bispecific monoclonal antibodies (bsAbs) against human IgG (HIgG) and horseradish peroxidase (HRP).</p> <p><bold>Results and discussion.</bold> The groups did not show differences in IgG levels (regardless of sex) with both methods giving comparable results. However, «IgG Total-ELISA-BEST» kit revealed statistically significant differences in mean serum IgG levels in subgroups of male patients depending on the levels of antibodies to viral RBD-antigen: below and above 400 BAU/ml. In the first subgroup (10 men) the mean serum IgG content was 14.3 ± 4.1 mg/mL, while in the second (6 men) — 6.9 ± 2.7 mg/mL.</p> <p><bold>Conclusion.</bold> Sera obtained before pandemic contained the same mean IgG concentrations as sera from donors vaccinated with «Sputnik V» and COVID-19 patients. The relatively decreased mean IgG concentration was found only in COVID-19 male patients with anti-RBD antibodies levels above 400 BAU/ml. In light of literature data on association of decreased serum IgG with COVID-19 severity, it would be reasonable to further compare larger groups, taking into account clinical differences. The possibility of using bsAbs for human Ig measurements by competitive EIA was demonstrated.</p></abstract><trans-abstract xml:lang="ru"><p><bold>Введение.</bold> Измерение концентрации сывороточного иммуноглобулина G (IgG) используется в диагностике и мониторинге многих заболеваний. Поэтому важно изучить влияние пандемии COVID-19 на уровень IgG в популяции.</p> <p><bold>Целью </bold>работы был сравнительный анализ среднего уровня сывороточного IgG в образцах крови, полученных от госпитализированных пациентов с COVID-19 (<italic>n</italic> = 31), здоровых доноров до начала пандемии (<italic>n</italic> = 30) и доноров, вакцинированных препаратом «Спутник V» (не болевших COVID-19; <italic>n</italic> = 34).</p> <p><bold>Материалы и методы.</bold> IgG измеряли двумя методами твердофазного иммуноферментного анализа (ИФА): зарегистрированной российской системой «IgG общий-ИФА-БЕСТ» и сконструированным в лаборатории конкурентным ИФА, основанным на моноклональных биспецифических антителах к IgG человека и пероксидазе хрена.</p> <p><bold>Результаты и обсуждение.</bold> Отличий в среднем уровне сывороточного IgG в трёх группах не обнаружили (независимо от пола); оба метода дали соотносимые результаты. Однако система «IgG общий- ИФА-БЕСТ» выявила статистически значимые различия в концентрации сывороточного IgG в подгруппах пациентов-мужчин с разным уровнем антител к вирусному антигену к рецепторсвязывающему домену (receptor-binding domain, RBD): ниже и выше 400 BAU/мл. У 10 мужчин с RBD-антигеном &lt; 400 BAU/мл содержание IgG было 14,3 ± 4,1 мг/мл, у 6 мужчин с RBD-антигеном &gt; 400 BAU/мл — 6,9 ± 2,7 мг/мл.</p> <p><bold>Заключение.</bold> Средний уровень IgG в сыворотках крови, полученных до пандемии, не отличался от такового у здоровых доноров, вакцинированных препаратом «Спутник V», или пациентов, госпитализированных в связи с COVID-19. При этом обнаружено сравнительное снижение средней концентрации IgG у пациентов-мужчин с COVID-19 и уровнем анти-RBD антител &gt; 400 BAU/мл. В учётом данных литературы об ассоциации снижения сывороточного IgG с тяжестью COVID-19 целесообразно сравнить выборки большего размера.</p></trans-abstract><kwd-group xml:lang="en"><kwd>COVD 19: SARS-CoV-2</kwd><kwd>anti RBD antibodies</kwd><kwd>IgG</kwd><kwd>immunoglobulin G</kwd><kwd>bispecific antibodies</kwd><kwd>enzyme immunoassay</kwd></kwd-group><kwd-group xml:lang="ru"><kwd>биспецифические антитела</kwd><kwd>IgG человека</kwd><kwd>COVID-19</kwd><kwd>SARS-CoV-2</kwd><kwd>антитела к RBD</kwd><kwd>иммуноглобулин G</kwd></kwd-group><funding-group><funding-statement xml:lang="en">The study was carried out on the scientific equipment of the Collective Usage Center «I.I. Mechnikov NIIVS», Moscow, Russia, with the financial support of the project by the Russian Federation represented by the Ministry of Science of Russia, Agreement No. 075-15-2021-676 dated 28.07.2021.</funding-statement><funding-statement xml:lang="ru">Работа выполнена с использованием научного оборудования центра коллективного пользования НИИВС им. И.И. Мечникова — при финансовой поддержке проекта Российской Федерацией в лице Минобрнауки России (Соглашение № 075-15-2021-676 от 28.07.2021).</funding-statement></funding-group></article-meta></front><body></body><back><ref-list><ref id="B1"><label>1.</label><mixed-citation>Khan S.R., van der Burgh A.C., Peeters R.P., et al. Determinants of serum immunoglobulin levels: a systematic review and meta-analysis. Front. Immunol. 2021;12:664526. DOI: https://doi.org/10.3389/fimmu.2021.664526</mixed-citation></ref><ref id="B2"><label>2.</label><mixed-citation>Чучалин А.Г. Болезни, ассоциированные с иммуноглобулином G. Терапевтический архив. 2018;90(3):4–9. Chuchalin A.G. Disease associated with immunoglobulin G. Therapeutic Archive. 2018;90(3):4–9. DOI: https://doi.org/10.26442/terarkh20189034-9 EDN: https://elibrary.ru/ytpvaq</mixed-citation></ref><ref id="B3"><label>3.</label><mixed-citation>Husain-Syed F., Vadász I., Wilhelm J., et al. Immunoglobulin deficiency as an indicator of disease severity in patients with COVID-19. Am. J. Physiol. Lung Cell. Mol. Physiol. 2021;320(4):L590–9. DOI: https://doi.org/10.1152/ajplung.00359.2020</mixed-citation></ref><ref id="B4"><label>4.</label><mixed-citation>Çölkesen F., Kepenek K.E., Vatansev H., et al. Memory B cells and serum immunoglobulins are associated with disease severity and mortality in patients with COVID-19. Postgrad. Med. J. 2022;98(1164):765–71. DOI: https://doi.org/10.1136/postgradmedj-2021-140540</mixed-citation></ref><ref id="B5"><label>5.</label><mixed-citation>Vrettou C.S., Vassiliou A.G., Kakkas I., et al. Low admission immunoglobulin G levels predict poor outcome in patients with mild-to-critical COVID-19: A prospective, single-center study. J. Epidemiol. Glob. Health. 2021;11(4):338–43. DOI: https://doi.org/10.1007/s44197-021-00002-8</mixed-citation></ref><ref id="B6"><label>6.</label><mixed-citation>Barzegar-Amini M., Mahmoudi M., Dadgarmoghaddam M., et al. Comparison of serum total IgA levels in severe and mild COVID-19 patients and control group. J. Clin. Immunol. 2022;42(1):10–8. DOI: https://doi.org/10.1007/s10875-021-01149-6</mixed-citation></ref><ref id="B7"><label>7.</label><mixed-citation>Фролова Е.В., Филиппова Л.В., Учеваткина А.В. и др. Иммунологические особенности пациентов с СOVID-19 в зависимости от степени тяжести заболевания. Проблемы медицинской микологии. 2021;23(1):3–13. Frolova E.V., Filippova L.V., Uchevatkina A.V., et al. Immunological features of patients with COVID-19 depending on the severity of the disease. Problems in Medical Mycology. 2021;23(1):3–13. DOI: https://doi.org/10.24412/1999-6780-2021-1-3-13 EDN: https://elibrary.ru/jlyvnq</mixed-citation></ref><ref id="B8"><label>8.</label><mixed-citation>Dmitriev D.A., Massino Y.S., Segal O.L., et al. The comparison of the ability of monoclonal antibodies directed to different proteins (human IgG, human myoglobin and HRP) and bispecific antibodies derived thereof to bind antigens immobilized on a surface of a solid phase. Clin. Chim. Acta. 2001;309(1):57–71. DOI: https://doi.org/10.1016/S0009-8981(01)00531-9</mixed-citation></ref><ref id="B9"><label>9.</label><mixed-citation>Dmitriev D.A., Massino Y.S., Segal O.L., et al. Analysis of the binding of bispecific monoclonal antibodies with immobilized antigens (human IgG and horseradish peroxidase) using a resonant mirror biosensor. J. Immunol. Methods. 2002;261(1-2):103–18. DOI: https://doi.org/10.1016/S0022-1759(01)00558-0</mixed-citation></ref><ref id="B10"><label>10.</label><mixed-citation>Массино Ю.С., Суханова Л.Л., Кизим Е.А. и др. Получение бифункциональных антител к IgG человека и пероксидазе хрена и их использование для тестирования антител к ВИЧ. Бюллетень экспериментальной биологии и медицины. 1994; 117(3):291–3. Massino Y.S., Sukhanova L.L., Kizim E.A., et al. Production of bifunctional monoclonal antibodies to human IgG and horseradish peroxidase and their utilization for testing anti-HIV antibodies. Bulletin of Experimental Biology and Medicine. 1994;117(3): 294–6. DOI: https://doi.org/10.1007/BF02444168</mixed-citation></ref><ref id="B11"><label>11.</label><mixed-citation>Parashar A., Sarkar S., Ganguly A., et al. Bispecific antibodies for diagnostic applications. In: Kontermann R., ed. Bispecific Antibodies. Berlin, Heidelberg;2011:349–67. DOI: https://doi.org/10.1007/978-3-642-20910-9_19</mixed-citation></ref><ref id="B12"><label>12.</label><mixed-citation>Laemmli U.K. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970;227(5259):680–5. DOI: https://doi.org/10.1038/227680a0</mixed-citation></ref><ref id="B13"><label>13.</label><mixed-citation>Fasman G.D., ed. Handbook of Biochemistry and Molecular Biology. Section A: Proteins. Volume 2. Cleveland;1976:383.</mixed-citation></ref><ref id="B14"><label>14.</label><mixed-citation>Ishikawa E., Imagawa M., Hashida S., et al. Enzyme-labeling of antibodies and their fragments for enzyme immunoassay and immunohistochemical staining. J. Immunoassay. 1983;4(3):209–327. DOI: https://doi.org/10.1080/15321818308057011</mixed-citation></ref><ref id="B15"><label>15.</label><mixed-citation>Смирнова М.Б., Дергунова Н.Н., Кизим Е.А. и др. Изучение антигенсвязывающих свойств биспецифических моноклональных антител. Биохимия. 1997;62(1):51–9. Smirnova M.B., Dergunova N.N., Kizim E.A., et al. Study of antigen-binding properties of bispecific antibodies. Biochemistry. 1997;62(1):41–51.</mixed-citation></ref><ref id="B16"><label>16.</label><mixed-citation>Wasiluk T., Sredzinska M., Rogowska A., et al. Analysis of the IgG subclass profile and IgG sum-total discrepancy in COVID-19 convalescent plasma donors: A single-centre prospective cohort study. Transfus. Apher. Sci. 2022;62(1):103527. DOI: https://doi.org/10.1016/j.transci.2022.103527</mixed-citation></ref><ref id="B17"><label>17.</label><mixed-citation>Garcia-Beltran W.F., Lam E.C., Astudillo M.G., et al. COVID-19-neutralizing antibodies predict disease severity and survival. Cell. 2021;184(2):476–88.e11. DOI: https://doi.org/10.1016/j.cell.2020.12.015</mixed-citation></ref><ref id="B18"><label>18.</label><mixed-citation>Lagadinou M., Zareifopoulos N., Gkentzi D., et al. Alterations in lymphocyte subsets and monocytes in patients diagnosed with SARS-CoV-2 pneumonia: a mini review of the literature. Eur. Rev. Med. Pharmacol. Sci. 2021;25(15):5057–62. DOI: https://doi.org/10.26355/eurrev_202108_26463</mixed-citation></ref><ref id="B19"><label>19.</label><mixed-citation>Sosa-Hernández V.A., Torres-Ruíz J., Cervantes-Díaz R., et al. B cell subsets as severity-associated signatures in COVID-19 patients. Front. Immunol. 2020;11:611004. DOI: https://doi.org/10.3389/fimmu.2020.611004</mixed-citation></ref><ref id="B20"><label>20.</label><mixed-citation>Wildner N.H., Ahmadi P., Schulte S., et al. B cell analysis in SARS-CoV-2 versus malaria: Increased frequencies of plasmablasts and atypical memory B cells in COVID-19. J. Leukoc. Biol. 2021;109(1):77–90. DOI: https://doi.org/10.1002/JLB.5COVA0620-370RR</mixed-citation></ref><ref id="B21"><label>21.</label><mixed-citation>Søndergaard J.N., Tulyeu J., Edahiro R., et al. A sex-biased imbalance between Tfr, Tph, and atypical B cells determines antibody responses in COVID-19 patients. Proc. Natl Acad. Sci. USA. 2023;120(4):e2217902120. DOI: https://doi.org/10.1073/pnas.2217902120</mixed-citation></ref><ref id="B22"><label>22.</label><mixed-citation>Taban E.M., Tintinger G.R., Joseph D., et al. Lymphopenia and IgG2 subclass deficiency in patients with severe COVID-19 pneumonia. Afr. J. Thorac Crit. Care Med. 2021;27(2):41–6. DOI: https://doi.org/10.7196/AJTCCM.2021.v27i2.134</mixed-citation></ref><ref id="B23"><label>23.</label><mixed-citation>Cervia C., Zurbuchen Y., Taeschler P., et al. Immunoglobulin signature predicts risk of post-acute COVID-19 syndrome. Nat. Commun. 2022;13(1):446. DOI: https://doi.org/10.1038/s41467-021-27797-1</mixed-citation></ref><ref id="B24"><label>24.</label><mixed-citation>Hasan A.O., Bomze D., Risch L., et al. Severe coronavirus disease 2019 (COVID-19) is associated with elevated serum immunoglobulin (Ig) A and antiphospholipid IgA antibodies. Clin. Infect. Dis. 2021;73(9):e2869–74. DOI: https://doi.org/10.1093/cid/ciaa1496</mixed-citation></ref><ref id="B25"><label>25.</label><mixed-citation>Montrucchio G., Sales G., Balzani E., et al. Effectiveness of mid-regional pro-adrenomedullin, compared to other biomarkers (including lymphocyte subpopulations and immunoglobulins), as a prognostic biomarker in COVID-19 critically ill patients: New evidence from a 15-month observational prospective study. Front. Med. (Lausanne). 2023;10:1122367. DOI: https://doi.org/10.3389/fmed.2023.1122367</mixed-citation></ref></ref-list></back></article>
