RESUMO
<p><b>OBJECTIVE</b>To identify the location of major immunodominant antigenic region and study the relationship between the gene heterogeneity and immunoreactivity via detecting antigenic reactivity of synthetic peptides deriving from immunodominant region in different genotypes of hepatitis C virus (HCV) NS5a gene.</p><p><b>METHODS</b>In total, 305 non-identical 30-mer long and overlapping by 15 aa peptides derived from HCV NS5a region from codon 2,182 to 2,343 among 45 unique published HCV sequences in GenBank corresponding to different genotype were designed and synthesized. The amino acid sequences of all peptides were compared with DNA Star software. The antigenic reactivity of those peptides was detected with indirect ELISA with both anti-HCV and anti-NS5 positive serum.</p><p><b>RESULTS</b>The sequences showed highly conserved among HCV genotype in regions 2,272-2,301 and 2,302-2,331 as compared to regions 2,212-2,241 and 2,257-2,286. The peptides basing on amino acid residues among 2,212-2,241, 2,272-2,301 and 2,302-2,331 showed stronger immunoreactivity than any other peptides. Eighteen peptides derived from this region showed a broad immunoreactivity, 3 of them could react with 96% of anti-HCV positive sera. Whereas the immunoreactivity of the peptides derived from the region showing highly variable among HCV genotype was found to react more strongly with homologous-genotype sera.</p><p><b>CONCLUSION</b>The major linear antigenic region was located at amino acid residues among 2,212-2,241, 2,272-2,301 and 2,302-2,331; the short synthetic peptide derived from NS5a region at position 2,212-2,241, 2,272-2,301 and 2,302-2,331 can be used for efficient detection of HCV antibody; some peptides showed genotype specific immuunoreactivity.</p>