biopreparatБИОпрепараты. Профилактика, диагностика, лечениеBiological Products. Prevention, Diagnosis, Treatment2221-996X2619-1156Scientific Centre for Expert Evaluation of Medicinal Products10.30895/2221-996X-2021-21-3-178-192biopreparat-374Research ArticleОРИГИНАЛЬНЫЕ СТАТЬИORIGINAL ARTICLESОценка Т-клеточного иммунитета к SARS-CoV-2 у переболевших и вакцинированных против COVID-19 лиц с помощью ELISPOT набора ТиграТест® SARS-CoV-2Assessment of T-cell immunity to SARS-CoV-2 in COVID-19 convalescents and vaccinated subjects, using TigraTest® SARS-CoV-2 ELISPOT kithttps://orcid.org/0000-0003-2695-8869ПотеряевД. А.PoteryaevD. A.

Потеряев Дмитрий Александрович, кандидат биологических наук

ул. Владимирская, д. 14, пос. Вольгинский, Петушинский район, Владимирская область, 601125

Dmitry A. Poteryaev, Cand. Sci. (Biol.)

14 Vladimirskaya St., Volginsky town, Petushinskiy District, Vladimir Region 601125

poteryaev@ibcgenerium.ruhttps://orcid.org/0000-0001-5841-7587АббасоваС. Г.AbbasovaS. G.

Аббасова Светлана Георгиевна, доктор биологических наук

ул. Владимирская, д. 14, пос. Вольгинский, Петушинский район, Владимирская область, 601125

Svetlana G. Abbasova, Dr. Sci. (Biol.)

14 Vladimirskaya St., Volginsky town, Petushinskiy District, Vladimir Region 601125

ИгнатьеваП. Е.IgnatyevaP. E.

Игнатьева Полина Евгеньевна

ул. Владимирская, д. 14, пос. Вольгинский, Петушинский район, Владимирская область, 601125

Polina E. Ignatyeva

14 Vladimirskaya St., Volginsky town, Petushinskiy District, Vladimir Region 601125

https://orcid.org/0000-0003-0023-0028СтрижаковаО. М.StrizhakovaO. M.

Стрижакова Ольга Михайловна, кандидат ветеринарных наук

ул. Владимирская, д. 14, пос. Вольгинский, Петушинский район, Владимирская область, 601125

Olga M. Strizhakova, Cand. Sci. (Vet.)

14 Vladimirskaya St., Volginsky town, Petushinskiy District, Vladimir Region 601125

https://orcid.org/0000-0003-2398-4615КолесникС. В.KolesnikS. V.

Колесник Светлана Владимировна

ул. Тестовская, д. 10, Москва, 123112

Svetlana V. Kolesnik

10 Testovskaya St., Moscow 123112

https://orcid.org/0000-0002-1314-894XХамитовР. А.KhamitovR. A.

Хамитов Равиль Авгатович, доктор медицинских наук, профессор

ул. Владимирская, д. 14, пос. Вольгинский, Петушинский район, Владимирская область, 601125

Ravil A. Khamitov, Dr. Sci. (Med.), Professor

14 Vladimirskaya St., Volginsky town, Petushinskiy District, Vladimir Region 601125

Общество с ограниченной ответственностью «Международный биотехнологический центр «ГЕНЕРИУМ»РоссияInternational Biotechnology Center “GENERIUM”Russian FederationАкционерное общество «ГЕНЕРИУМ»РоссияGENERIUM JSCRussian Federation202102102021213178192Copyright © Потеряев Д.А., Аббасова С.Г., Игнатьева П.Е., Стрижакова О.М., Колесник С.В., Хамитов Р.А., 20212021Потеряев Д.А., Аббасова С.Г., Игнатьева П.Е., Стрижакова О.М., Колесник С.В., Хамитов Р.А.Poteryaev D.A., Abbasova S.G., Ignatyeva P.E., Strizhakova O.M., Kolesnik S.V., Khamitov R.A.Данная работа распространяется под лицензией Creative Commons Attribution 4.0.This work is licensed under a Creative Commons Attribution 4.0 License.https://www.biopreparations.ru/jour/article/view/374

С началом пандемии COVID-19 в мире и Российской Федерации был разработан ряд молекулярно-биологических тестов для диагностики инфекции, вызванной SARS-CoV-2. Однако результаты применения многочисленных серологических тестов свидетельствуют об их недостаточной чувствительности или специфичности. У существенной части пациентов с подтвержденным ПЦР-диагнозом COVID-19 специфические антитела не обнаруживаются. Существуют доказательства того, что у части выздоровевших гуморальный иммунный ответ является относительно кратковременным. В ряде публикаций показано, что Т-клеточный ответ на человеческие коронавирусы, включая SARS-CoV-1, MERS и SARS-CoV-2, может быть сильным и долговременным. Оценка Т-клеточного иммунитета к SARS-CoV-2 важна не только для стратификации рисков и определения потенциально защищенных групп населения с иммунитетом, приобретенным вследствие перенесенной инфекции, но и для определения иммуногенности и потенциальной эффективности разрабатываемых вакцин. Существующие методики количественной или полуколичественной оценки специфического Т-клеточного ответа применяются в основном в научных исследованиях и не стандартизованы. Цель работы: разработка и апробация тест-системы для выполнения стандартизованной методики определения специфических к антигенам SARS-CoV-2 Т-клеток в периферической крови человека in vitro. Материалы и методы: разработанный компанией «ГЕНЕРИУМ» набор ТиграТест® SARS-CoV-2, принцип работы которого заключается в определении количества Т-клеток, секретирующих гамма-интерферон in vitro. Исследования проводили на образцах венозной крови добровольцев трех групп: условно здоровых, переболевших COVID-19, прошедших вакцинацию против COVID-19. Результаты: разработана тест-система для определения специфических к антигенам SARS-CoV-2 Т-клеток в периферической крови человека in vitro. Показана специфичность и определена предварительная чувствительность теста ТиграТест® SARS-CoV-2. Исследован диапазон и величина Т-клеточного ответа у переболевших и вакцинированных. Показан выраженный Т-клеточный ответ и у части лиц с отсутствующими симптомами или неподтвержденным диагнозом. Обнаружено, что среднее значение Т-клеточного ответа в отношении пептидов белка-шипа (S-белка) выше у вакцинированных, чем у переболевших. Найдена корреляция между тяжестью заболевания и уровнем Т-клеточного ответа. Определен удельный вклад различных групп антигенов в Т-клеточный ответ после перенесенного заболевания COVID-19. Выводы: набор ТиграТест® SARS-CoV-2 является специфичным и чувствительным инструментом в оценке Т-клеточного иммунитета к вирусу SARS-CoV-2, в том числе и для вакцинированных. Разработанный набор целесообразно использовать в клинической практике для комплексной оценки иммунитета к SARS-CoV-2.

With the onset of the COVID-19 pandemic, a number of molecular-based tests have been developed to diagnose SARS-CoV-2 infection. However, numerous available serological tests lack sufficient sensitivity or specificity. They do not detect specific antibodies in a significant proportion of patients with PCR-confirmed COVID-19. There is evidence that some convalescents have a relatively short-lived humoral immunity. In contrast, a number of publications have shown that T-cell response to human coronaviruses, including SARS-CoV-1, MERS, and SARS-CoV-2, can be strong and long-term. Assessment of T-cell immunity to SARS-CoV-2 is important not only for stratification of risks and identification of potentially protected populations with immunity acquired as a result of previous infection, but also for determining immunogenicity and potential efficacy of vaccines under development. The existing methods of quantitative or semi-quantitative assessment of specific T-cell response are mainly used in scientific research and are not standardised. The aim of the study was to develop and verify experimentally a test kit to be used in a standardised procedure for in vitro determination of T-cells specific to SARS-CoV-2 antigens, in human peripheral blood. Materials and methods: the TigraTest® SARS-CoV-2 kit developed by GENERIUM, which determines the number of T-cells secreting interferon gamma in vitro, was tested in the study. Samples of venous blood of volunteers from three different groups were analysed in the study: presumably healthy volunteers; COVID-19 convalescents; individuals vaccinated against SARS-CoV-2. Results: the authors developed the TigraTest® SARS-CoV-2 kit for in vitro determination of T-cells specific to SARS-CoV-2 antigens in human peripheral blood, demonstrated its specificity and performed preliminary assessment of its sensitivity. The study analysed the range and magnitude of the T-cell response in convalescent and vaccinated individuals. A pronounced T-cell response was also shown in some individuals with no symptoms or with unconfirmed diagnosis. It was discovered that the mean T-cell response to peptides of the spike protein (S-protein) was higher in the vaccinated individuals than in the convalescent patients. A correlation was determined between the severity of the disease and the level of T-cell response. Specific contributions of various groups of antigens to the T-cell response after COVID-19 infection were also determined. Conclusions: the TigraTest® SARS-CoV-2 kit is a specific and sensitive tool for the assessment of T-cell immunity to the SARS-CoV-2 virus, which can also be used for vaccinated individuals. The kit may be used in clinical practice for comprehensive assessment of immunity to SARS-CoV-2.

ELISPOTSARS-CoV-2COVID-19Т-лимфоцитыВ-клеткиантителавакцинаиммунитетELISPOTSARS-CoV-2COVID-19T-cellsB-cellsantibodiesvaccineimmunityАвторы благодарны коллективу группы компаний «ГЕНЕРИУМ» за помощь в организации работы. Набор для исследовательских целей ТиграТест<sup>®</sup> SARS-CoV-2 разработан ООО «МБЦ «ГЕНЕРИУМ» в рамках контракта на выполнение НИР с АО «ГЕНЕРИУМ».The authors are grateful to the Generium group of companies for help in organising this study. The TigraTest<sup>®</sup> SARS-CoV-2 kit was developed by IBC GENERIUM, LLC under an R&D contract with GENERIUM, JSC.ReferencesMelgaço JG, Azamor T, Ano Bom APD. Protective immunity after COVID-19 has been questioned: What can we do without SARS-CoV-2-IgG detection? Cell Immunol. 2020;353:104114. http://doi.org/10.1016/j.cellimm.2020.104114Melgaço JG, Azamor T, Ano Bom APD. Protective immunity after COVID-19 has been questioned: What can we do without SARS-CoV-2-IgG detection? Cell Immunol. 2020;353:104114. http://doi.org/10.1016/j.cellimm.2020.104114Altmann DM, Boyton RJ. SARS-CoV-2 T cell immunity: specificity, function, durability, and role in protection. Science Immunology. 2020;5(49):eabd6160. http://doi.org/10.1126/sciimmunol.abd6160Altmann DM, Boyton RJ. SARS-CoV-2 T cell immunity: specificity, function, durability, and role in protection. Science Immunology. 2020;5(49):eabd6160. http://doi.org/10.1126/sciimmunol.abd6160Peng Y, Mentzer AJ, Liu G, Yao X, Yin Z, Dong D, et al. Broad and strong memory CD4 + and CD8 + T cells induced by SARS-CoV-2 in UK convalescent individuals following COVID-19. Nat Immunol. 2020;21(11):1336–45. http://doi.org/10.1038/s41590-020-0782-6Peng Y, Mentzer AJ, Liu G, Yao X, Yin Z, Dong D, et al. Broad and strong memory CD4 + and CD8 + T cells induced by SARS-CoV-2 in UK convalescent individuals following COVID-19. Nat Immunol. 2020;21(11):1336–45. http://doi.org/10.1038/s41590-020-0782-6Swadling L, Maini MK. T cells in COVID-19 — united in diversity. Nat Immunol. 2020;21(11):1307–8. http://doi.org/10.1038/s41590-020-0798-ySwadling L, Maini MK. T cells in COVID-19 — united in diversity. Nat Immunol. 2020;21(11):1307–8. http://doi.org/10.1038/s41590-020-0798-yWeiskopf D, Schmitz KS, Raadsen MP, Grifoni A, Okba NM, Endeman H, et al. Phenotype and kinetics of SARS-CoV-2specific T cells in COVID-19 patients with acute respiratory distress syndrome. Sci Immunol. 2020;5(48):eabd2071. http://doi.org/10.1126/sciimmunol.abd2071Weiskopf D, Schmitz KS, Raadsen MP, Grifoni A, Okba NM, Endeman H, et al. Phenotype and kinetics of SARS-CoV-2specific T cells in COVID-19 patients with acute respiratory distress syndrome. Sci Immunol. 2020;5(48):eabd2071. http://doi.org/10.1126/sciimmunol.abd2071Woldemeskel BA, Kwaa AK, Garliss CC, Laeyendecker O, Ray SC, Blankson JN. Healthy donor T cell responses to common cold coronaviruses and SARS-CoV-2. J Clin Invest. 2020;130(12):6631–8. http://doi.org/10.1172/JCI143120Woldemeskel BA, Kwaa AK, Garliss CC, Laeyendecker O, Ray SC, Blankson JN. Healthy donor T cell responses to common cold coronaviruses and SARS-CoV-2. J Clin Invest. 2020;130(12):6631–8. http://doi.org/10.1172/JCI143120Dos Santos LA, Filho PGG, Silva AMF, Santos JVG, Santos DS, Aquino MM, et al. Recurrent COVID-19 including evidence of reinfection and enhanced severity in thirty Brazilian healthcare workers. J Infect. 2021;82(3):399–406. http://doi.org/10.1016/j.jinf.2021.01.020Dos Santos LA, Filho PGG, Silva AMF, Santos JVG, Santos DS, Aquino MM, et al. Recurrent COVID-19 including evidence of reinfection and enhanced severity in thirty Brazilian healthcare workers. J Infect. 2021;82(3):399–406. http://doi.org/10.1016/j.jinf.2021.01.020Boyton RJ, Altmann DM. Risk of SARS-CoV-2 reinfection after natural infection. Lancet. 2021;397(10280):1161–3. http://doi.org/10.1016/S0140-6736(21)00662-0Boyton RJ, Altmann DM. Risk of SARS-CoV-2 reinfection after natural infection. Lancet. 2021;397(10280):1161–3. http://doi.org/10.1016/S0140-6736(21)00662-0Hansen CH, Michlmayr D, Gubbels SM, Mølbak K, Ethelberg S. Assessment of protection against reinfection with SARS-CoV-2 among 4 million PCR-tested individuals in Denmark in 2020: a population-level observational study. Lancet. 2021;397(10280):1204–12. http://doi.org/10.1016/S0140-6736(21)00575-4Hansen CH, Michlmayr D, Gubbels SM, Mølbak K, Ethelberg S. Assessment of protection against reinfection with SARS-CoV-2 among 4 million PCR-tested individuals in Denmark in 2020: a population-level observational study. Lancet. 2021;397(10280):1204–12. http://doi.org/10.1016/S0140-6736(21)00575-4Tan W, Lu Y, Zhang J, Wang J, Dan Y, Tan Z, et al. Viral kinetics and antibody responses in patients with COVID-19. MedRxiv. 2020. https://doi.org/10.1101/2020.03.24.20042382Tan W, Lu Y, Zhang J, Wang J, Dan Y, Tan Z, et al. Viral kinetics and antibody responses in patients with COVID-19. MedRxiv. 2020. https://doi.org/10.1101/2020.03.24.20042382Gallais F, Velay A, Nazon C, Wendling M-J, Partisani M, Sibilia J, et al. Intrafamilial exposure to SARS-CoV-2 associated with cellular immune response without seroconversion, France. Emerg. Infect. Diseases. 2021;27(1):113–21. https://doi.org/10.3201/eid2701.203611Gallais F, Velay A, Nazon C, Wendling M-J, Partisani M, Sibilia J, et al. Intrafamilial exposure to SARS-CoV-2 associated with cellular immune response without seroconversion, France. Emerg. Infect. Diseases. 2021;27(1):113–21. https://doi.org/10.3201/eid2701.203611Channappanavar R, Zhao J, Perlman S. T cell-mediated immune response to respiratory coronaviruses. Immunol Res. 2014;59(1-3):118–28. https://doi.org/10.1007/s12026-014-8534-zChannappanavar R, Zhao J, Perlman S. T cell-mediated immune response to respiratory coronaviruses. Immunol Res. 2014;59(1-3):118–28. https://doi.org/10.1007/s12026-014-8534-zIbarrondo FJ, Fulcher JA, Goodman-Meza D, Elliott J, Hofmann C, Hausner MA, et al. Rapid decay of anti-SARSCoV-2 antibodies in persons with mild Covid-19. N Engl J Med. 2020;383(11):1085–7. https://doi.org/10.1056/NEJMc2025179 Erratum in: N Engl J Med. 2020; 383(11):e74. https://doi.org/10.1056/NEJMx200017Ibarrondo FJ, Fulcher JA, Goodman-Meza D, Elliott J, Hofmann C, Hausner MA, et al. Rapid decay of anti-SARSCoV-2 antibodies in persons with mild Covid-19. N Engl J Med. 2020;383(11):1085–7. https://doi.org/10.1056/NEJMc2025179 Erratum in: N Engl J Med. 2020; 383(11):e74. https://doi.org/10.1056/NEJMx200017Tay MZ, Poh CM, Rénia L, MacAry PA, Ng LF. The trinity of COVID-19: immunity, inflammation and intervention. Nat Rev Immunol. 2020;20(6):363–74. https://doi.org/10.1038/s41577-020-0311-8Tay MZ, Poh CM, Rénia L, MacAry PA, Ng LF. The trinity of COVID-19: immunity, inflammation and intervention. Nat Rev Immunol. 2020;20(6):363–74. https://doi.org/10.1038/s41577-020-0311-8Zuo J, Dowell AC, Pearce H, Verma K, Long HM, Begum J, et al. Robust SARS-CoV-2-specific T cell immunity is maintained at 6 months following primary infection. Nat Immunol. 2021;22(5):620–6. https://doi.org/10.1038/s41590-021-00902-8Zuo J, Dowell AC, Pearce H, Verma K, Long HM, Begum J, et al. Robust SARS-CoV-2-specific T cell immunity is maintained at 6 months following primary infection. Nat Immunol. 2021;22(5):620–6. https://doi.org/10.1038/s41590-021-00902-8Wyllie D, Jones HE, Mulchandani R, Trickey A, TaylorPhillips S, Brooks T, et al. SARS-CoV-2 responsive T cell numbers and anti-Spike IgG levels are both associated with protection from COVID-19: a prospective cohort study in keyworkers. medRxiv. 2020.11.02.20222778. https://doi.org/10.1101/2020.11.02.20222778Wyllie D, Jones HE, Mulchandani R, Trickey A, TaylorPhillips S, Brooks T, et al. SARS-CoV-2 responsive T cell numbers and anti-Spike IgG levels are both associated with protection from COVID-19: a prospective cohort study in keyworkers. medRxiv. 2020.11.02.20222778. https://doi.org/10.1101/2020.11.02.20222778Mandalakas AM, Highsmith HY, Harris NM, Pawlicka A, Kirchner HL. T-SPOT.TB performance in routine pediatric practice in a low TB burden setting. Pediatr Infect Dis J. 2018;37(4):292–7. https://doi.org/10.1097/INF.0000000000001792Mandalakas AM, Highsmith HY, Harris NM, Pawlicka A, Kirchner HL. T-SPOT.TB performance in routine pediatric practice in a low TB burden setting. Pediatr Infect Dis J. 2018;37(4):292–7. https://doi.org/10.1097/INF.0000000000001792Потеряев ДА, Хамитов РА, Ефимов ГА, Шустер АМ. Перспективы использования технологической платформы ELISPOT в системе противоэпидемических мероприятий против новой коронавирусной инфекции COVID-19. БИОпрепараты Профилактика, диагностика, лечение. 2020;20(3):146–58. https://doi.org/10.30895/2221-996X-2020-20-3-146-158Poteryaev DA, Khamitov RA, Efimov GA, Shuster AM. Prospects for using the ELISPOT technological platform as part of anti-epidemic measures against the new coronavirus infection COVID-19. BIOpreparaty. Profilaktika, diagnostika, lechenie = BIOpreperations. Prevention, Diagnosis, Treatment. 2020;20(3):146–58 (In Russ.) https://doi.org/10.30895/2221-996X-2020-20-3-146-158Mallone R, Mannering S, Brooks-Worrell BM, DurinovicBelló I, Cilio CM, Wong FS, et al. Isolation and preservation of peripheral blood mononuclear cells for analysis of islet antigen-reactive T cell responses: position statement of the T-Cell Workshop Committee of the Immunology of Diabetes Society. Clin Exp Immunol. 2011;163(1):33–49. https://doi.org/10.1111/j.1365-2249.2010.04272.xMallone R, Mannering S, Brooks-Worrell BM, DurinovicBelló I, Cilio CM, Wong FS, et al. Isolation and preservation of peripheral blood mononuclear cells for analysis of islet antigen-reactive T cell responses: position statement of the T-Cell Workshop Committee of the Immunology of Diabetes Society. Clin Exp Immunol. 2011;163(1):33–49. https://doi.org/10.1111/j.1365-2249.2010.04272.xSekine T, Perez-Potti A, Rivera-Ballesteros O, Strålin K, Gorin JB, Olsson A, et al. Robust T cell immunity in convalescent individuals with asymptomatic or mild COVID-19. Cell. 2020;183(1):158–68.e14. https://doi.org/10.1016/j.cell.2020.08.017Sekine T, Perez-Potti A, Rivera-Ballesteros O, Strålin K, Gorin JB, Olsson A, et al. Robust T cell immunity in convalescent individuals with asymptomatic or mild COVID-19. Cell. 2020;183(1):158–68.e14. https://doi.org/10.1016/j.cell.2020.08.017Shomuradova AS, Vagida MS, Sheetikov SA, Zornikova KV, Kiryukhin D, Titov A, et al. SARS-CoV-2 epitopes are recognized by a public and diverse repertoire of human T cell receptors. Immunity. 2020;53(6):1245–57.e5. https://doi.org/10.1016/j.immuni.2020.11.004Shomuradova AS, Vagida MS, Sheetikov SA, Zornikova KV, Kiryukhin D, Titov A, et al. SARS-CoV-2 epitopes are recognized by a public and diverse repertoire of human T cell receptors. Immunity. 2020;53(6):1245–57.e5. https://doi.org/10.1016/j.immuni.2020.11.004Le Bert N, Tan AT, Kunasegaran K, Tham CYL, Hafezi M, Chia A, et al. SARS-CoV-2-specific T cell immunity in cases of COVID-19 and SARS, and uninfected controls. Nature. 2020;584(7821):457–62. https://doi.org/10.1038/s41586-020-2550-zLe Bert N, Tan AT, Kunasegaran K, Tham CYL, Hafezi M, Chia A, et al. SARS-CoV-2-specific T cell immunity in cases of COVID-19 and SARS, and uninfected controls. Nature. 2020;584(7821):457–62. https://doi.org/10.1038/s41586-020-2550-zMateus J, Grifoni A, Tarke A, Sidney J, Ramirez SI, Dan JM, et al. Selective and cross-reactive SARS-CoV-2 T cell epitopes in unexposed humans. Science. 2020;370(6512):89–94. https://doi.org/10.1126/science.abd3871Mateus J, Grifoni A, Tarke A, Sidney J, Ramirez SI, Dan JM, et al. Selective and cross-reactive SARS-CoV-2 T cell epitopes in unexposed humans. Science. 2020;370(6512):89–94. https://doi.org/10.1126/science.abd3871Reynolds CJ, Swadling L, Gibbons JM, Pade C, Jensen MP, Diniz MO, et al. Discordant neutralizing antibody and T cell responses in asymptomatic and mild SARS-CoV-2 infection. Sci Immunol. 2020;5(54):eabf3698. https://doi.org/10.1126/sciimmunol.abf3698Reynolds CJ, Swadling L, Gibbons JM, Pade C, Jensen MP, Diniz MO, et al. Discordant neutralizing antibody and T cell responses in asymptomatic and mild SARS-CoV-2 infection. Sci Immunol. 2020;5(54):eabf3698. https://doi.org/10.1126/sciimmunol.abf3698Nolan S, Vignali M, Klinger M, Dines JN, Kaplan IM, Svejnoha E, et al. A large-scale database of T-cell receptor beta (TCRβ) sequences and binding associations from natural and synthetic exposure to SARS-CoV-2. 2020. Preprint. Res Sq. 2020;rs.3.rs-51964. https://doi.org/10.21203/rs.3.rs-51964/v1Nolan S, Vignali M, Klinger M, Dines JN, Kaplan IM, Svejnoha E, et al. A large-scale database of T-cell receptor beta (TCRβ) sequences and binding associations from natural and synthetic exposure to SARS-CoV-2. 2020. Preprint. Res Sq. 2020;rs.3.rs-51964. https://doi.org/10.21203/rs.3.rs-51964/v1Yu J, Tostanoski LH, Peter L, Mercado NB, McMahan K, Mahrokhian SH, et al. DNA vaccine protection against SARSCoV-2 in rhesus macaques. Science. 2020;369(6505):806–11. https://doi.org/10.1126/science.abc6284Yu J, Tostanoski LH, Peter L, Mercado NB, McMahan K, Mahrokhian SH, et al. DNA vaccine protection against SARSCoV-2 in rhesus macaques. Science. 2020;369(6505):806–11. https://doi.org/10.1126/science.abc6284Logunov DY, Dolzhikova IV, Zubkova OV, Tukhvatullin AI, Shcheblyakov DV, Dzharullaeva AS, et al. Safety and immunogenicity of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine in two formulations: two open, non-randomised phase 1/2 studies from Russia. Lancet. 2020;396(10255):887–97. https://doi.org/10.1016/S0140-6736(20)31866-3Logunov DY, Dolzhikova IV, Zubkova OV, Tukhvatullin AI, Shcheblyakov DV, Dzharullaeva AS, et al. Safety and immunogenicity of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine in two formulations: two open, non-randomised phase 1/2 studies from Russia. Lancet. 2020;396(10255):887–97. https://doi.org/10.1016/S0140-6736(20)31866-3Todryk SM, Pathan AA, Keating S, Porter DW, Berthoud T, Thompson F, et al. The relationship between human effector and memory T cells measured by ex vivo and cultured ELISPOT following recent and distal priming. Immunology. 2009;128(1):83–91. https://doi.org/10.1111/j.1365-2567.2009.03073.xTodryk SM, Pathan AA, Keating S, Porter DW, Berthoud T, Thompson F, et al. The relationship between human effector and memory T cells measured by ex vivo and cultured ELISPOT following recent and distal priming. Immunology. 2009;128(1):83–91. https://doi.org/10.1111/j.1365-2567.2009.03073.xDan JM, Mateus J, Kato Y, Hastie KM, Yu ED, Faliti CE, et al. Immunological memory to SARS-CoV-2 assessed for up to 8 months after infection. Science. 20215;371(6529):eabf4063. https://doi.org/10.1126/science.abf4063Dan JM, Mateus J, Kato Y, Hastie KM, Yu ED, Faliti CE, et al. Immunological memory to SARS-CoV-2 assessed for up to 8 months after infection. Science. 20215;371(6529):eabf4063. https://doi.org/10.1126/science.abf4063Bauer T, Jilg W. Hepatitis B surface antigen-specific T and B cell memory in individuals who had lost protective antibodies after hepatitis B vaccination. Vaccine. 2006;24(5):572–7. https://doi.org/10.1016/j.vaccine.2005.08.058Bauer T, Jilg W. Hepatitis B surface antigen-specific T and B cell memory in individuals who had lost protective antibodies after hepatitis B vaccination. Vaccine. 2006;24(5):572–7. https://doi.org/10.1016/j.vaccine.2005.08.058Ferretti AP, Kula T, Wang Y, Nguyen DMV, Weinheimer A, Dunlap GS, et al. Unbiased screens show CD8+ T cells of COVID-19 patients recognize shared epitopes in SARS-CoV-2 that largely reside outside the spike protein. Immunity. 2020;53(5):1095–107.e3. https://doi.org/10.1016/j.immuni.2020.10.006Ferretti AP, Kula T, Wang Y, Nguyen DMV, Weinheimer A, Dunlap GS, et al. Unbiased screens show CD8+ T cells of COVID-19 patients recognize shared epitopes in SARS-CoV-2 that largely reside outside the spike protein. Immunity. 2020;53(5):1095–107.e3. https://doi.org/10.1016/j.immuni.2020.10.006

The authors declare that there are no conflicts of interest present.