SARS-CoV-2-specific T cell immunity in cases of COVID-19 and SARS and uninfected controls

The study “SARS-CoV-2-specific T cell immunity in cases of COVID-19 and SARS and uninfected controls” investigates T cell responses to SARS-CoV-2, including in individuals who recovered from COVID-19, those who recovered from SARS (caused by SARS-CoV), and unexposed donors.

Here’s a detailed summary:

  1. T Cell Responses in COVID-19 Convalescents: The study found that all COVID-19 convalescents (36 individuals) had CD4 and CD8 T cells recognizing multiple regions of the nucleocapsid (N) protein of SARS-CoV-2. The study’s focus on the N protein, a structural element, and non-structural proteins NSP7 and NSP13, was due to their abundance and high homology across betacoronaviruses, suggesting potential cross-reactivity and long-lasting immunity​​.
  2. Long-lasting T Cell Responses from SARS: Remarkably, individuals who had recovered from SARS 17 years earlier still exhibited T cells reactive to the N protein of SARS-CoV and showed robust cross-reactivity to SARS-CoV-2’s N protein. This suggests that betacoronavirus infections can induce durable and versatile T cell immunity, which could be significant for understanding immunity longevity following COVID-19​​.
  3. SARS-CoV-2-Specific T Cells in Unexposed Donors: In a surprising discovery, 19 out of 37 unexposed donors (neither infected with SARS-CoV nor SARS-CoV-2) demonstrated SARS-CoV-2-specific T cell responses. These donors showed a different pattern of immunodominance, frequently targeting NSP7 and NSP13 proteins alongside the N protein. This finding indicates the presence of pre-existing T cell immunity in the general population, potentially derived from exposure to other human coronaviruses known to cause common colds​​.
  4. Implications for COVID-19 Immunity and Vaccine Development: The study’s findings are crucial for understanding COVID-19’s immunological landscape. The persistence of T cell responses years after SARS infection and the presence of SARS-CoV-2 reactive T cells in people not exposed to the virus suggest a complex and potentially protective landscape of T cell immunity. These insights are valuable for vaccine development and in predicting the long-term immunity landscape post-COVID-19 infection.

In summary, this study provides significant insights into T cell immunity related to SARS-CoV-2, highlighting the presence of specific T cell responses in individuals recovered from COVID-19 and SARS, and even in unexposed individuals. It underscores the complexity and potential durability of T cell-mediated immunity in response to coronavirus infections, including COVID-19. This research contributes to the broader understanding of immune responses to SARS-CoV-2 and has implications for vaccine development and predicting long-term immunity against the virus.

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