A group from the University of Ferrara, Italy, has published a study linking HHV-6A to Hashimoto’s Thyroiditis (HT), an autoimmune disorder that is the most common of all thyroid diseases. The study found that HHV-6 prevalence was detected significantly more frequently among thyroid fine needle aspirates (FNA) from HT individuals than controls (82% vs. 10%, respectively). In addition, the group demonstrated that thyroid cells infected with both HHV-6A and HHV-6B became susceptible to NK-mediated killing, providing evidence of a potential mechanism for HHV-6-induced autoimmunity.
Of note, the pattern of infection established by HHV-6 in HT patients was substantially different than that observed in healthy individuals. HT biopsies were more frequently positive for HHV-6 and exhibited increased viral loads compared to controls, and active HHV-6 transcription was observed in HT thyrocytes compared to latent infection in HHV-6-infected control thyroids. Furthermore, the presence of HHV-6 infection was found localized mainly to thyrocytes, rather than in lymphocytes infiltrating the lesion, and increased prevalence of latent HHV-6 infection was seen in PBMCs overall.