SEQUENCE SIMILARITY BETWEEN THYROID SELF-PROTEIN AND HEPATITIS C VIRUS POLYPROTEIN: possible triggering mechanism of autoimmune thyroiditis

• Published in: Arquivos de gastroenterologia 2016-09, Vol.53 (3), p.185-191
• Main Authors: Sousa, Maristella de Araújo Carvalho, Paraná, Raymundo, Andrade, Luís Jesuíno de Oliveira
• Format: Article
• Language: English
• Subjects: Autoantigens - genetics; Biologia computacional; Epitopes - genetics; GASTROENTEROLOGY & HEPATOLOGY; Genotyping Techniques; Hepacivirus; Hepacivirus - genetics; Hepacivirus - immunology; Homologia de sequência de aminoácidos; Humans; Molecular Mimicry - genetics; Polyproteins - genetics; Sequence Homology, Amino Acid; Thyroiditis, Autoimmune - immunology; Thyroiditis, Autoimmune - virology; Tireoidite; Viral Proteins - genetics
• ISSN: 0004-2803; 1678-4219; 1678-4219; 0004-2803
• DOI: 10.1590/s0004-28032016000300012

- Exposure to viral antigens that share amino acid sequence similar with self- antigens might trigger autoimmune diseases in genetically predisposed individuals, and the molecular mimicry theory suggests that epitope mimicry between the virus and human proteins can activate autoimmune disease. - The purpose of this study is to explore the possible sequence similarity between the amino acid sequences of thyroid self-protein and hepatitis C virus proteins, using databanks of proteins and immunogenic peptides, to explain autoimmune thyroid disease. - Were performed the comparisons between the amino acid sequence of the hepatitis C virus polyprotein and thyroid self-protein human, available in the database of National Center for Biotechnology Information on Basic Local Alignment Search Tool. - The sequence similarity was related each hepatitis C virus genotype to each thyroid antigen. The similarities between the thyroid and the viral peptides ranged from 21.0 % (31 identical residues out of 147 amino acid in the sequence) to 71.0% (5 identical residues out of 7 amino acid in the sequence). - Bioinformatics data, suggest a possible pathogenic link between hepatitis C virus and autoimmune thyroid disease. Through of molecular mimicry is observed that sequences similarities between viral polyproteins and self-proteins thyroid could be a mechanism of induction of crossover immune response to self-antigens, with a breakdown of self-tolerance, resulting in autoimmune thyroid disease.