Lasting memories of SARS-CoV-2 infection

Abstract

Maintaining virus-specific adaptive immunity is critical for ongoing protection against SARS-CoV-2 infection. In this issue, Breton et al. (2021. J. Exp. Med.https://doi.org/10.1084/jem.20202515) identify polyfunctional SARS-CoV-2-specific T cell responses in the peripheral blood of individuals who recovered from COVID-19 that were present at 1 mo and persisted until 6 mo after infection.

Insights from Maya M.L. Poon and Donna L. Farber.

Maintenance and evolution of adaptive immunity to SARS-CoV-2 infection. (A) T cell–mediated immunity consists of SARS-CoV-2–specific CD4⁺ and CD8⁺ T cells that produce cytokines upon stimulation and are reactive against a broad range of viral epitopes. Charts show relative responses to different viral epitopes (S, Memb, NCAP, AP3a) 1 and 6 mo after infection. CD4⁺ T cell responses specific for the S protein predominate and are maintained long-term, while T cells specific for other viral epitopes are reduced at 6 mo after infection; CD4⁺ T cell responses are more robust than CD8⁺ T cell responses. (B) Humoral immunity to SARS-CoV-2 is maintained by circulating antibodies, particularly IgG and IgA, and memory B cells. Memory B cells undergo somatic hypermutation and prolonged germinal center reactions after the resolution of natural infection, resulting in increased neutralization potency over time.