A high CMV-specific T cell response associates with SARS-CoV-2-specific IL-17 T cell production.

Human cytomegalovirus (CMV) is a widespread persistent herpes virus requiring lifelong immune surveillance to maintain latency. Such long-term interactions with the immune system may be associated with deleterious effects including immune exhaustion and senescence. Regarding the COVID-19 pandemic, we asked whether CMV-specific cellular and humoral activity could influence immune responses toward SARS-CoV-2 and/or disease severity. All adults with mild (n = 15) and severe (n = 14) COVID-19 were seropositive for anti-CMV IgG, but negative for IgM antibodies. Antibody titers did not correlate with COVID-19 severity. Six patients presented elevated frequencies of CMV-specific CD4 + and CD8 + T cells producing IFNγ, IL-17, and TNFα, designated as CMV high responders (hiT CMV). In comparison to low CMV responders, hiT CMV individuals exhibited higher frequencies of SARS-CoV-2-specific CD4 + IL-17 + and CD8 + IFNγ + , IL-17 + or TNFα + T cells. These results indicate that high frequencies of CMV-specific T cells may be associated with a SARS-CoV-2-reactive profile skewed toward Th17-dominated immunity.