RESUMEN
Hepatitis C virus (HCV) isolates have been divided into six genotypes (1 to 6). The duration of hepatitis C standard treatment is 48 weeks for patients infected with HCV genotype 1 vs 24 weeks for those infected with genotypes 2 and 3. A total of 1544 HCV isolates from chronic patients living in the southern Brazilian states of Rio Grande do Sul (RS, n = 627) and Santa Catarina (SC, n = 917) were genotyped by restriction fragment length polymorphism (RFLP) of polymerase chain reaction (PCR) products. In RS, 338 (53.9 percent; 95 percent CI 50.0 - 57.8 percent), 34 (5.4 percent; 95 percent CI 3.8 - 7.4 percent) and, 255 (40.7 percent; 95 percent CI 36.9 - 44.6 percent) samples were from genotypes 1, 2, and 3, respectively. In SC, 468 (51 percent; 95 percent CI 47.8 - 54.2 percent), 26 (2.9 percent; 95 percent CI 1.9 - 4.1 percent) and, 423 (46.1 percent; 95 percent CI 42.9 - 49.3 percent) samples were from genotypes 1, 2, and 3, respectively. Genotyping results were confirmed by direct nucleotide sequencing of PCR products derived from 68 samples, without any discrepancy between PCR-RFLP and nucleotide sequencing methods. In conclusion, almost half of the hepatitis C patients from South of Brazil are infected by genotypes 2 and 3 and, these results have important consequential therapeutic implications as they can be treated for only 24 weeks, not 48.