tetano
Editor, Senior Moderator
J Clin Invest
. 2023 May 23;e170011.
doi: 10.1172/JCI170011. Online ahead of print. Prevalence and functional profile of SARS-CoV-2 T cells in asymptomatic Kenyan adults
Taraz Samandari[SUP] 1 [/SUP], Joshua Ongalo[SUP] 2 [/SUP], Kimberly McCarthy[SUP] 3 [/SUP], Richard K Biegon[SUP] 4 [/SUP], Philister Madiega[SUP] 2 [/SUP], Anne Mithika[SUP] 2 [/SUP], Joseph Orinda[SUP] 2 [/SUP], Grace M Mboya[SUP] 2 [/SUP], Patrick Mwaura[SUP] 5 [/SUP], Omu Anzala[SUP] 5 [/SUP], Clayton Onyango[SUP] 1 [/SUP], Fredrick O Oluoch[SUP] 6 [/SUP], Eric M Osoro[SUP] 7 [/SUP], Charles-Antoine Dutertre[SUP] 8 [/SUP], Nicole Tan[SUP] 9 [/SUP], Shou Kit Hang[SUP] 9 [/SUP], Smrithi Hariharaputran[SUP] 9 [/SUP], David C Lye[SUP] 10 [/SUP], Amy Herman-Roloff[SUP] 1 [/SUP], Nina Le Bert[SUP] 9 [/SUP], Antonio Bertoletti[SUP] 9 [/SUP]
Affiliations
Background: SARS-CoV-2 infection in Africa has been characterized by less severe disease than elsewhere but the profile of SARS-CoV-2 specific adaptive immunity in this largely asymptomatic spread has not been studied.
Methods: We collected blood and nasopharyngeal samples from rural Kenyans (n=80) without respiratory symptoms since 2019, had no contact with COVID-19 cases or received COVID-19 vaccines and were negative for current SARS-CoV-2 infection. We analyzed spike-specific antibodies and T cells specific for SARS-CoV-2 structural (membrane, nucleocapsid and spike) and accessory (ORF3a, ORF7, ORF8) proteins. Pre-pandemic samples collected in urban Nairobi, Kenya (n=13) between 2015-2016 and samples of mild-moderately symptomatic COVID-19 convalescents (n=36) living in the urban environment of Singapore were also studied.
Results: Among asymptomatic Kenyans, we detected anti-spike antibodies in 41.0% and T cell responses against ≥2 SARS-CoV-2 proteins in 82.5%. The pre-pandemic samples from Nairobi had low-level, monospecific responses. Furthermore, distinct from cellular immunity in European and Asian COVID-19 convalescents, strong T cell immunogenicity was observed against viral accessory proteins (ORF3a, ORF8) and not structural proteins, as well as a higher IL-10/IFN-γ ratio cytokine profile.
Conclusions: The high incidence of T cell responses against different SARS-CoV-2 proteins in largely seronegative participants suggests that serosurveys underestimate SARS-CoV-2 prevalence in settings where asymptomatic infections prevail. Similar observations have been made with other coronavirus infections such as MERS and SARS-CoV-1. The functional and antigen-specific profile of SARS-CoV-2 specific T cells in these African individuals suggests that genetic or environmental factors play a role in the development of protective antiviral immunity.
Fundings: U.S. Centers for Disease Control and Prevention, Division of Global Health Protection; the Singapore Ministry of Health's National Medical Research Council.
. 2023 May 23;e170011.
doi: 10.1172/JCI170011. Online ahead of print. Prevalence and functional profile of SARS-CoV-2 T cells in asymptomatic Kenyan adults
Taraz Samandari[SUP] 1 [/SUP], Joshua Ongalo[SUP] 2 [/SUP], Kimberly McCarthy[SUP] 3 [/SUP], Richard K Biegon[SUP] 4 [/SUP], Philister Madiega[SUP] 2 [/SUP], Anne Mithika[SUP] 2 [/SUP], Joseph Orinda[SUP] 2 [/SUP], Grace M Mboya[SUP] 2 [/SUP], Patrick Mwaura[SUP] 5 [/SUP], Omu Anzala[SUP] 5 [/SUP], Clayton Onyango[SUP] 1 [/SUP], Fredrick O Oluoch[SUP] 6 [/SUP], Eric M Osoro[SUP] 7 [/SUP], Charles-Antoine Dutertre[SUP] 8 [/SUP], Nicole Tan[SUP] 9 [/SUP], Shou Kit Hang[SUP] 9 [/SUP], Smrithi Hariharaputran[SUP] 9 [/SUP], David C Lye[SUP] 10 [/SUP], Amy Herman-Roloff[SUP] 1 [/SUP], Nina Le Bert[SUP] 9 [/SUP], Antonio Bertoletti[SUP] 9 [/SUP]
Affiliations
- PMID: 37219944
- DOI: 10.1172/JCI170011
Background: SARS-CoV-2 infection in Africa has been characterized by less severe disease than elsewhere but the profile of SARS-CoV-2 specific adaptive immunity in this largely asymptomatic spread has not been studied.
Methods: We collected blood and nasopharyngeal samples from rural Kenyans (n=80) without respiratory symptoms since 2019, had no contact with COVID-19 cases or received COVID-19 vaccines and were negative for current SARS-CoV-2 infection. We analyzed spike-specific antibodies and T cells specific for SARS-CoV-2 structural (membrane, nucleocapsid and spike) and accessory (ORF3a, ORF7, ORF8) proteins. Pre-pandemic samples collected in urban Nairobi, Kenya (n=13) between 2015-2016 and samples of mild-moderately symptomatic COVID-19 convalescents (n=36) living in the urban environment of Singapore were also studied.
Results: Among asymptomatic Kenyans, we detected anti-spike antibodies in 41.0% and T cell responses against ≥2 SARS-CoV-2 proteins in 82.5%. The pre-pandemic samples from Nairobi had low-level, monospecific responses. Furthermore, distinct from cellular immunity in European and Asian COVID-19 convalescents, strong T cell immunogenicity was observed against viral accessory proteins (ORF3a, ORF8) and not structural proteins, as well as a higher IL-10/IFN-γ ratio cytokine profile.
Conclusions: The high incidence of T cell responses against different SARS-CoV-2 proteins in largely seronegative participants suggests that serosurveys underestimate SARS-CoV-2 prevalence in settings where asymptomatic infections prevail. Similar observations have been made with other coronavirus infections such as MERS and SARS-CoV-1. The functional and antigen-specific profile of SARS-CoV-2 specific T cells in these African individuals suggests that genetic or environmental factors play a role in the development of protective antiviral immunity.
Fundings: U.S. Centers for Disease Control and Prevention, Division of Global Health Protection; the Singapore Ministry of Health's National Medical Research Council.