Altered pre-existing SARS-CoV-2-specific T cell responses in elderly individuals

Area of Science:

• Immunology
• Virology
• Gerontology

Background:

• Pre-existing SARS-CoV-2-specific T cells, not antibodies, are found in some unexposed individuals, potentially influencing COVID-19 clinical outcomes.
• Age is a known risk factor for COVID-19, but its impact on SARS-CoV-2-specific T cell responses is not well understood.

Purpose of the Study:

• To investigate the effect of age on pre-existing and infection-induced SARS-CoV-2-specific T cell responses.
• To identify viral antigens that elicit age-independent T cell responses for potential vaccine strategies.

Main Methods:

• Comparative analysis of T cell responses to SARS-CoV-2 Spike (S), Nucleoprotein (N), and Membrane (M) proteins in young and elderly donors.
• Assessment of both pre-existing T cell immunity in unexposed individuals and T cell responses post-SARS-CoV-2 infection.

Main Results:

• Elderly donors (>70 years) exhibited significantly lower pre-existing T cell responses to S and N proteins compared to young donors.
• Substantial pre-existing T cell responses to the M protein were observed in both young and elderly individuals.
• Following SARS-CoV-2 infection, T cell responses to S, N, and M proteins were comparable across all age groups.

Conclusions:

• SARS-CoV-2 infection elicits T cell responses to various antigens irrespective of age.
• The repertoire of target antigens for long-lived memory T cells against SARS-CoV-2 may diminish with age.
• T cell responses to specific viral proteins like M are maintained with age, offering a promising avenue for developing effective vaccines for the elderly.