Molecular epidemiology of the hepatitis C virus in Brazil.

Hepatitis C virus (HCV) is a major cause of liver disease throughout the world. The genome of this virus consists of approximately 10,000 bp and codes for 10 mature polypeptides. Genome sequence comparison has revealed the existence of six major genotypes and a large number of subtypes. The genotypes can be distinguished by whole genome or genome fragment sequencing, genotype specific amplification of a genomic region or PCR amplification, followed by hybridization or restriction digestion, among other methods. There is a markedly heterogeneous geographical distribution of the HCV genotypes in the world. Different genotypes have been linked to distinct clinical outcomes and to differences in the susceptibility of the virus to interferon treatment. Several studies have been conducted to determine the distribution of HCV genotypes among different groups of individuals in Brazil. Most of these studies indicate a higher prevalence of genotype 1, followed by genotypes 3 and 2. Differences in genotypes can affect serological detection as well as the clinical outcome of the disease and sensibility to interferon treatment. Further studies need to be conducted to determine the degree of differentiation of circulating HCV genotypes in different patient groups in Brazil.