Human herpesvirus 6A active infection in patients with autoimmune Hashimoto's thyroiditis

Braz J Infect Dis. 2019 Nov-Dec;23(6):435-440. doi: 10.1016/j.bjid.2019.10.004. Epub 2019 Nov 18.


Background: Hypothyroidism due to Hashimoto's thyroiditis (HT) is the commonest autoimmune endocrine illness in which antibodies against thyroid organ result in inflammation. The disease has a complex etiology that involves genetic and environmental influences. Viral infections may be involved in triggering of the disease as their molecular mimicry enhance autoimmune responses. Human herpesvirus-6 (HHV-6) is recognized for its contribution to some autoimmune diseases.

Objective: In the current study, the prevalence of HHV-6 active infection in patients with HT and with non-autoimmune thyroid disorders were compared with patients with euthyroidism. In addition, a correlation between presence of HHV-6 infections and HT was investigated.

Methods: A total of 151 patients with clinically and laboratory confirmed HT, 59 patients with non-autoimmune thyroid disorders, and 32 patients with normal thyroid function were included in the study. For further confirmation of HT disease, all the precipitants were tested for anti-thyroid peroxidase (TPO), and anti-thyroglobulin (TG) antibodies. For detection of both HHV-6 types A and B, nested PCR and restriction enzyme digestion were used. HHV-6 DNA positive samples were further investigated by DNA sequencing analysis.

Results: HHV-6A DNA was found in serum sample of 57 out of 151 patients (38%) with HT, which was significantly more often than in patients with non-autoimmune thyroid disorders (p=0.001). However, HHV-6 DNA was not detected in serum samples of euthyroid subjects.

Conclusions: The results support a possible role for active HHV-6A infection, demonstrated by the presence of HHV-6 DNA in sera, in the development of HT.

Keywords: Autoimmune diseases; Hashimoto disease; Human herpesvirus 6; Prevalence.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • DNA, Viral / analysis
  • Female
  • Hashimoto Disease / virology*
  • Herpesvirus 6, Human / genetics*
  • Humans
  • Male
  • Middle Aged
  • Polymerase Chain Reaction
  • Roseolovirus Infections / virology*
  • Thyroid Gland / virology
  • Young Adult


  • DNA, Viral