Pre-existing T-cell immunity to SARS-CoV-2 in unexposed healthy controls in Ecuador, as detected with a COVID-19 Interferon-Gamma Release Assay
Background: Studies of T-cell immune responses against SARS-CoV-2 are important in understanding the immune status of individuals or populations. Here, we use a simple, cheap, and rapid whole blood stimulation assay - an Interferon-Gamma Release Assay (IGRA) - to study T-cell immunity to SARS-CoV-2...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2021-04-01
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| Series: | International Journal of Infectious Diseases |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S120197122100120X |
| _version_ | 1819120672378454016 |
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| author | Gustavo Echeverría Ángel Guevara Josefina Coloma Alison Mera Ruiz María Mercedes Vasquez Eduardo Tejera Jacobus H. de Waard |
| author_facet | Gustavo Echeverría Ángel Guevara Josefina Coloma Alison Mera Ruiz María Mercedes Vasquez Eduardo Tejera Jacobus H. de Waard |
| author_sort | Gustavo Echeverría |
| collection | DOAJ |
| description | Background: Studies of T-cell immune responses against SARS-CoV-2 are important in understanding the immune status of individuals or populations. Here, we use a simple, cheap, and rapid whole blood stimulation assay - an Interferon-Gamma Release Assay (IGRA) - to study T-cell immunity to SARS-CoV-2 in convalescent COVID-19 patients and in unexposed healthy contacts from Quito, Ecuador. Methods: Interferon-gamma (INF-γ) production was measured in the heparinized blood of convalescent and unexposed subjects after stimulation for 24 h with the SARS-CoV-2 Spike S1 protein, the Receptor Binding Domain (RBD) protein or the Nucleocapsid (NP) protein, respectively. The presence of IgG-RBD protein antibodies in both study groups was determined with an “in-house” ELISA. Results: As measured with INF-γ production, 80% of the convalescent COVID-19 patients, all IgG-RBD seropositive, had a strong T-cell response. However, unexpectedly, 44% of unexposed healthy controls, all IgG-RBD seronegative, had a strong virus-specific T-cell response with the COVID-19 IGRA, probably because of prior exposure to common cold-causing coronaviruses or other viral or microbial antigens. Conclusion and Discussion: The high percentage of unexposed healthy subjects with a pre-existing immunity suggests that a part of the Ecuadorian population is likely to have SARS-CoV-2 reactive T-cells. Given that the IGRA technique is simple and can be easily scaled up for investigations where high numbers of patients are needed, this COVID-19 IGRA may serve to determine if the T-cell only response represents protective immunity to SARS-CoV-2 infection in a population-based study. |
| first_indexed | 2024-12-22T06:24:23Z |
| format | Article |
| id | doaj.art-85f9e34cf7a74c2a8244e94677d0aee0 |
| institution | Directory Open Access Journal |
| issn | 1201-9712 |
| language | English |
| last_indexed | 2024-12-22T06:24:23Z |
| publishDate | 2021-04-01 |
| publisher | Elsevier |
| record_format | Article |
| series | International Journal of Infectious Diseases |
| spelling | doaj.art-85f9e34cf7a74c2a8244e94677d0aee02022-12-21T18:35:53ZengElsevierInternational Journal of Infectious Diseases1201-97122021-04-011052125Pre-existing T-cell immunity to SARS-CoV-2 in unexposed healthy controls in Ecuador, as detected with a COVID-19 Interferon-Gamma Release AssayGustavo Echeverría0Ángel Guevara1Josefina Coloma2Alison Mera Ruiz3María Mercedes Vasquez4Eduardo Tejera5Jacobus H. de Waard6Instituto de Investigación en Zoonosis-CIZ, Universidad Central del Ecuador, EcuadorInstituto de Biomedicina, carrera de Medicina, Universidad Central, Quito, EcuadorDivision of Infectious Diseases and Vaccinology, School of Public Health, University of California, Berkeley, CA, USABioGENA, División Investigación y Desarrollo, Quito, EcuadorOne Health Research Group. Facultad de Ciencias de la Salud, Universidad de Las Américas (UDLA), Quito, EcuadorOne Health Research Group. Facultad de Ciencias de la Salud, Universidad de Las Américas (UDLA), Quito, EcuadorOne Health Research Group. Facultad de Ciencias de la Salud, Universidad de Las Américas (UDLA), Quito, Ecuador; Corresponding author at: Universidad de Las Américas, Calle Queri y Granados, Campus Queri: Bloque 5, piso 1, Quito, Ecuador.Background: Studies of T-cell immune responses against SARS-CoV-2 are important in understanding the immune status of individuals or populations. Here, we use a simple, cheap, and rapid whole blood stimulation assay - an Interferon-Gamma Release Assay (IGRA) - to study T-cell immunity to SARS-CoV-2 in convalescent COVID-19 patients and in unexposed healthy contacts from Quito, Ecuador. Methods: Interferon-gamma (INF-γ) production was measured in the heparinized blood of convalescent and unexposed subjects after stimulation for 24 h with the SARS-CoV-2 Spike S1 protein, the Receptor Binding Domain (RBD) protein or the Nucleocapsid (NP) protein, respectively. The presence of IgG-RBD protein antibodies in both study groups was determined with an “in-house” ELISA. Results: As measured with INF-γ production, 80% of the convalescent COVID-19 patients, all IgG-RBD seropositive, had a strong T-cell response. However, unexpectedly, 44% of unexposed healthy controls, all IgG-RBD seronegative, had a strong virus-specific T-cell response with the COVID-19 IGRA, probably because of prior exposure to common cold-causing coronaviruses or other viral or microbial antigens. Conclusion and Discussion: The high percentage of unexposed healthy subjects with a pre-existing immunity suggests that a part of the Ecuadorian population is likely to have SARS-CoV-2 reactive T-cells. Given that the IGRA technique is simple and can be easily scaled up for investigations where high numbers of patients are needed, this COVID-19 IGRA may serve to determine if the T-cell only response represents protective immunity to SARS-CoV-2 infection in a population-based study.http://www.sciencedirect.com/science/article/pii/S120197122100120XPre-existing immunityCOVID-19SARS-CoV-2T cellsInterferon-Gamma (IFN-γ) release assay (IGRA)ELISPOT |
| spellingShingle | Gustavo Echeverría Ángel Guevara Josefina Coloma Alison Mera Ruiz María Mercedes Vasquez Eduardo Tejera Jacobus H. de Waard Pre-existing T-cell immunity to SARS-CoV-2 in unexposed healthy controls in Ecuador, as detected with a COVID-19 Interferon-Gamma Release Assay International Journal of Infectious Diseases Pre-existing immunity COVID-19 SARS-CoV-2 T cells Interferon-Gamma (IFN-γ) release assay (IGRA) ELISPOT |
| title | Pre-existing T-cell immunity to SARS-CoV-2 in unexposed healthy controls in Ecuador, as detected with a COVID-19 Interferon-Gamma Release Assay |
| title_full | Pre-existing T-cell immunity to SARS-CoV-2 in unexposed healthy controls in Ecuador, as detected with a COVID-19 Interferon-Gamma Release Assay |
| title_fullStr | Pre-existing T-cell immunity to SARS-CoV-2 in unexposed healthy controls in Ecuador, as detected with a COVID-19 Interferon-Gamma Release Assay |
| title_full_unstemmed | Pre-existing T-cell immunity to SARS-CoV-2 in unexposed healthy controls in Ecuador, as detected with a COVID-19 Interferon-Gamma Release Assay |
| title_short | Pre-existing T-cell immunity to SARS-CoV-2 in unexposed healthy controls in Ecuador, as detected with a COVID-19 Interferon-Gamma Release Assay |
| title_sort | pre existing t cell immunity to sars cov 2 in unexposed healthy controls in ecuador as detected with a covid 19 interferon gamma release assay |
| topic | Pre-existing immunity COVID-19 SARS-CoV-2 T cells Interferon-Gamma (IFN-γ) release assay (IGRA) ELISPOT |
| url | http://www.sciencedirect.com/science/article/pii/S120197122100120X |
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