Association of active human herpesvirus-6 (HHV-6) infection with autoimmune thyroid gland diseases.
OBJECTIVE
Viral infections frequently have been cited as important environmental factors implicated in the onset of autoimmune thyroiditis (AIT). The aim of this study was to determine the involvement of HHV-6 infection in the development of autoimmune thyroiditis.


METHODS
This study included 45 patients (42 female and 3 male; median age 47.00 IQR 38.50-57.00) with histologically, laboratory, and clinically confirmed autoimmune thyroiditis, as well as 30 autopsied subjects (26 female and 4 male; median age 58.50, IQR 51.50-67.00) without thyroid pathologies and 30 healthy blood donors (25 female and 5 male; median age 33.50, IQR 27.75-44.25) as controls. Results were obtained by applying molecular virology and immunohistochemistry techniques.


RESULTS
The presence of persistent HHV-6 infection in AIT patients was significantly higher (p 0.0058) than in the control group (44/45 (98%) vs. 23/30 (77%), respectively). Also, a significantly higher frequency of HHV-6 activation marker (U79/80 mRNA) was found in patients' thyroid gland tissue samples with AIT in comparison with the control group (18/44 (41%) vs. 1/17 (6%), respectively; p 0.0118). The median HHV-6 load was found to be higher in patients with active viral infection than in patients without it (2147, IQR 971-4188 vs. 551, IQR 145-1589 copies/1×106cells; p 0.003). The presence of HHV-6 antigen expression was demonstrated in intrafollicular cellular clusters and immunohistochemistry indicated thyrocytes in the follicle wall.


CONCLUSIONS
These findings provide evidence of strong HHV-6 infection association with AIT development.
Riga Stradiņš University, A. Kirchenstein Institute of Microbiology and Virology, Latvia. Electronic address: alina.sultanova@rsu.lv.
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Sultanova
Riga Stradiņš University, A. Kirchenstein Institute of Microbiology and Virology, Latvia.
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Cistjakovs
Riga Stradiņš University, A. Kirchenstein Institute of Microbiology and Virology, Latvia.
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Gravelsina
Riga Stradiņš University, A. Kirchenstein Institute of Microbiology and Virology, Latvia.
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Chapenko
Riga Stradiņš University, Study Department, Latvia.
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Roga
Riga East Clinical University Hospital, Gailezers Clinic, Latvia.
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Cunskis
Riga Stradiņš University, A. Kirchenstein Institute of Microbiology and Virology, Latvia.
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Nora-Krukle
Institute of Anatomy and Anthropology, Riga Stradiņš University, Riga, Latvia.
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Groma
Riga Stradiņš University, A. Kirchenstein Institute of Microbiology and Virology, Latvia.
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Ventina
Riga Stradiņš University, A. Kirchenstein Institute of Microbiology and Virology, Latvia.
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Murovska
D000328:Adult; D001323:Autoantibodies; D001324:Autoantigens / Q000276:immunology; D001327:Autoimmune Diseases; D016022:Case-Control Studies; D005260:Female; D015967:Gene Expression Regulation, Viral / Q000502:physiology; D005814:Genes, Viral; D016679:Genome, Viral; D015654:Herpesvirus 6, Human; D006801:Humans; D007453:Iodide Peroxidase / Q000276:immunology; D033862:Iron-Binding Proteins / Q000276:immunology; D008297:Male; D008875:Middle Aged; D019349:Roseolovirus Infections / Q000150:complications* / Q000276:immunology / Q000821:virology*; D013954:Thyroglobulin / Q000276:immunology; D013961:Thyroid Gland / Q000821:virology; D013966:Thyroiditis / Q000276:immunology* / Q000821:virology*; D013972:Thyrotropin / Q000276:immunology; D019562:Viral Load
D001323:Autoantibodies; D001324:Autoantigens; D033862:Iron-Binding Proteins; D013972:Thyrotropin; D013954:Thyroglobulin; C056658:TPO protein, human; D007453:Iodide Peroxidase
Active infection; Autoimmune thyroiditis; HHV-6; U79/80; Viral load