PT  - JOURNAL ARTICLE
AU  - Bert, Nina Le
AU  - Clapham, Hannah E
AU  - Tan, Anthony T
AU  - Chia, Wan Ni
AU  - Tham, Christine YL
AU  - Lim, Jane M
AU  - Kunasegaran, Kamini
AU  - Tan, Linda
AU  - Dutertre, Charles-Antoine
AU  - Shankar, Nivedita
AU  - Lim, Joey ME
AU  - Sun, Louisa Jin
AU  - Zahari, Marina
AU  - Tun, Zaw Myo
AU  - Kumar, Vishakha
AU  - Lim, Beng Lee
AU  - Lim, Siew Hoon
AU  - Chia, Adeline
AU  - Tan, Yee-Joo
AU  - Tambyah, Paul Anantharajah
AU  - Kalimuddin, Shirin
AU  - Lye, David
AU  - Low, Jenny GH
AU  - Wang, Lin-Fa
AU  - Wan, Wei Yee
AU  - Hsu, Li Yang
AU  - Bertoletti, Antonio
AU  - Tam, Clarence C
TI  - Highly functional virus-specific cellular immune response in asymptomatic SARS-CoV-2 infection
AID  - 10.1101/2020.11.25.399139
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.11.25.399139
4099  - http://biorxiv.org/content/early/2020/11/27/2020.11.25.399139.short
4100  - http://biorxiv.org/content/early/2020/11/27/2020.11.25.399139.full
AB  - The efficacy of virus-specific T cells in clearing pathogens involves a fine balance between their antiviral and inflammatory features. SARS-CoV-2-specific T cells in individuals who clear SARS-CoV-2 infection without symptoms or disease could reveal non-pathological yet protective characteristics. We therefore compared the quantity and function of SARS-CoV-2-specific T cells in a cohort of asymptomatic individuals (n=85) with that of symptomatic COVID-19 patients (n=76), at different time points after antibody seroconversion. We quantified T cells reactive to structural proteins (M, NP and Spike) using ELISpot assays, and measured the magnitude of cytokine secretion (IL-2, IFN-γ, IL-4, IL-6, IL-1β, TNF-α and IL-10) in whole blood following T cell activation with SARS-CoV-2 peptide pools as a functional readout. Frequencies of T cells specific for the different SARS-CoV-2 proteins in the early phases of recovery were similar between asymptomatic and symptomatic individuals. However, we detected an increased IFN-γ and IL-2 production in asymptomatic compared to symptomatic individuals after activation of SARS-CoV-2-specific T cells in blood. This was associated with a proportional secretion of IL-10 and pro-inflammatory cytokines (IL-6, TNF-α and IL-1β) only in asymptomatic infection, while a disproportionate secretion of inflammatory cytokines was triggered by SARS-CoV-2-specific T cell activation in symptomatic individuals. Thus, asymptomatic SARS-CoV-2 infected individuals are not characterized by a weak antiviral immunity; on the contrary, they mount a robust and highly functional virus-specific cellular immune response. Their ability to induce a proportionate production of IL-10 might help to reduce inflammatory events during viral clearance.Competing Interest StatementThe authors have declared no competing interest.