Evaluation of the association between human herpes virus 6 (HHV-6) and Hashimoto's thyroiditis

Abstract

Background and Objectives: Hashimoto's thyroiditis is a chronic inflammation and an autoimmune disease of the thyroid gland that causes hypothyroidism. Genetic, internal, and environmental factors are the causes of this disease. Because human herpes viruses such as herpesvirus type 6 (HHV-6) are involved in some autoimmune disorders, they may also play a role in causing this disease. This study aimed to evaluate the association between human herpes virus 6 (HHV-6) with Hashimoto's thyroiditis.
 Materials and Methods: In the present study, 64 samples of thyroid paraffin tissue including 32 samples of thyroid paraffin tissue of healthy individuals as control, and 32 samples of thyroid paraffin tissue of Hashimoto's thyroiditis patients were taken from the pathology department of Loghman Hakim Hospital in Tehran. A questionnaire collected demographic infor- mation of patients. After DNA extraction from the samples, the nested-PCR technique was performed using specific primers for HHV-6.
 Results: Totally, the HHV6-DNA was found in 34.4% of thyroid tissues of healthy individuals (81.8% female and 18.2% male) and 46.9% of patients with Hashimoto's thyroiditis (73.3% female and 26.7% male). It was found that this difference in virus frequency between the two groups was not statistically significant (P value=0.309). There was also no statistically significant relationship between the prevalence of human herpesvirus type 6 and age or sex.
 Conclusion: Based on the present study, the number of HHV-6-infected individuals in Hashimoto's patients and controls did not differ significantly; therefore, HHV-6 appears not to be associated with Hashimoto's thyroiditis.

Human herpesvirus type 6 in patients with systemic lupus erythematosus

“…In recent years, HHV-6 has been recognized as one of the infectious agents associated with autoimmune diseases. This virus frequently is detected in patients with Multiple Sclerosis, Hashimoto’s Thyroiditis and ACTD ( 6 , 8 ). The few studies conducted have not been able to show a direct link between HHV-6 and lupus diseases.…”

“…HHV-6 major capsid protein (MCP) gene was detected by a nested PCR test. The forward primer 5′-GCGTTTTCAGT-GTGTAGTTCGGCAG-3′ ( 11 ) and the reverse primer 5′-TGGCCGCATTCGTACAGATACGGAGG-3′ ( 11 ) were used in the first round of PCR which produced amplicon size equal 520 bp. The first set of primers amplifies the target DNA in the first round.…”

“…The second round enhances the specificity and yield of the desired amplicons. The forward primer 5′-GCTAGAACGTATTTGC TGC AGAACG-3’ ( 11 ) and the reverse primer 5′-ATCCGAAACAACT-GTCTGACTGGCA-3′ ( 11 ) with an amplicon size of 258 bp were used for the second run of PCR. The reaction mix included 10 μL of template DNA or control, 0.5 μL of each primer (10 pM stock), 12.5 μL of the master mix (Sinaclon, Iran) and 1.5 μL of nuclease-free water.…”

“…HHV-6B can cause exanthema subitum and is a common virus that infects more than 90% of people globally. After initial infection, the virus can remain latent in the body lifelong, and it can be reactivated frequently ( 6 ).…”

“…In addition, some viruses such as EBV can immortalize autoreactive effector cells. While numerous hypotheses have been offered to elucidate the mechanisms underlying virus-induced autoimmunity, the specific role and mechanism of HHV-6 in autoimmunity is still unknown and this is a research gap ( 6 ).…”