title: SEQUENCE SIMILARITY BETWEEN THYROID SELF-PROTEIN AND HEPATITIS C VIRUS POLYPROTEIN: possible triggering mechanism of autoimmune thyroiditis.
abstract: BACKGROUND
  - 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.
  
  
  OBJECTIVE
  - 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.
  
  
  METHODS
  - 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.
  
  
  RESULTS
  - 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).
  
  
  CONCLUSIONS
  - 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.
authors.affiliation: Programa de Pós-Graduação em Ciências da Saúde, Universidade Estadual de Santa Cruz, Ilhéus, BA, Brasil.
authors.forename: Maristella de Araújo Carvalho
authors.initials: Mde A
authors.lastname: Sousa
authors.affiliation: Faculdade de Medicina, Universidade Federal da Bahia, Salvador, BA, Brasil.
authors.forename: Raymundo
authors.initials: R
authors.lastname: Paraná
authors.affiliation: Programa de Pós-Graduação em Ciências da Saúde, Universidade Estadual de Santa Cruz, Ilhéus, BA, Brasil.
authors.forename: Luís Jesuíno de Oliveira
authors.initials: LJ
authors.lastname: Andrade
mesh_terms: D001324:Autoantigens / Q000235:genetics*; D000939:Epitopes / Q000235:genetics; D060005:Genotyping Techniques; D016174:Hepacivirus / Q000235:genetics* / Q000276:immunology; D006801:Humans; D018716:Molecular Mimicry / Q000235:genetics; D020815:Polyproteins / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D013967:Thyroiditis, Autoimmune / Q000276:immunology* / Q000821:virology; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D001324:Autoantigens; D000939:Epitopes; D020815:Polyproteins; D014764:Viral Proteins