Viral infections have been implicated in the onset or exacerbation of autoimmunity. In a study published in Nature Genetics, Sasa et al. investigate associations between the human blood DNA virome and autoimmunity or COVID-19.

The authors introduced a computational approach to accurately measure the total abundance of all genetically diverse anelloviruses, and found that anelloviral loads were significantly increased in individuals with systemic lupus erythematosus (SLE), rheumatoid arthritis or COVID-19 compared with healthy controls. Whereas anellovirus infection in SLE might reflect the patients’ immunosuppressed state, in COVID-19, high anelloviral loads (viraemia), but not the mere presence of anelloviruses, were correlated with disease severity, indicating potential contribution to disease exacerbation.