In particular, we and others reported a high prevalence of active human herpesvirus 6A (HHV-6A) infection in thyrocytes of Hashimoto’s thyroiditis (HT) patients [2, 3], who also display specific cellular and humoral anti-viral responses, increased NK killing of infected thyroid cells [3], and increased CD3-CD56brightCD16−NK cells, whose activation significantly correlates with plasma levels of anti-thyroid peroxidase (TPO) and anti-thyroglobulin (Tg) autoantibodies [4]. Here, TPO is linked to Hashimoto thyroiditis.