Transient and durable T cell reactivity after COVID-19

Area of Science:

• Immunology
• Infectious Diseases
• Virology

Background:

• Understanding T cell responses post-COVID-19 is crucial for assessing long-term immunity.
• Natural infection with SARS-CoV-2 elicits adaptive immune responses, but their duration and characteristics require further elucidation.

Purpose of the Study:

• To determine the polarity and duration of antigen-specific T cell reactivity after verified COVID-19.
• To characterize the distinct phases of T cell responses following natural SARS-CoV-2 infection.

Main Methods:

• Analysis of whole blood samples from convalescent COVID-19 patients (n=56, 30 patients) at 1-21 months post-infection.
• Stimulation of blood samples with nucleocapsid and spike protein peptides to measure cytokine production (IL-4, IL-12, IL-13, IL-17, IL-2, IFN-γ).

Main Results:

• Early T cell response (up to ~70 days) showed synchronous production of IL-4, IL-12, IL-13, and IL-17 against nucleocapsid antigens.
• Later T cell response (3-21 months) demonstrated stable and correlated levels of IL-2 and interferon-γ induced by nucleocapsid peptides.
• Similar cytokine dynamics were observed with spike protein stimulation in unvaccinated, convalescent individuals.

Conclusions:

• COVID-19 convalescence is characterized by two distinct T cell response phases: an early transient multipolar T helper response followed by a durable T helper 1-like response.
• These findings suggest the development of long-lasting T cell memory after natural SARS-CoV-2 infection.