Hepatitis C Virus Subtype 6a Infection in an Iranian Patient: A Case Report

Hepatitis C virus (HCV) isolates have been divided into six major genotypes, each of them further divided into several subtypes. Previous studies have shown that the most frequent genotype in Iranian patients with HCV infection is 1a, followed by 3a, 1b and 4. Infections with genotype 6 isolates have not previously been observed in these patients. In this report, we will describe the first diagnosis of HCV genotype-6 infection in Iran. The case was a 62-year-old man with positive anti-HCV antibody. Alanine aminotransferase and aspartate aminotransferase levels were 14 and 32 IU/L respectively. Viral RNA was extracted from plasma. HCV RNA level was determined using real-time reverse transcription polymerase chain reaction (PCR). Following the synthesis of the complementary DNA, 5’-UTR/core region of the HCV genome was amplified and subjected to direct sequencing. Genetic distances were estimated and phylogenetic tree was constructed. HCV viral load was 9,572,718 IU/mL. The mean inter-genotypic distance between the case sequence and the corresponding sequences of other genotype 6 isolates was 3.7%. In the phylogenetic tree, the 5’-UTR/core sequence of the subject was located in a cluster representing HCV subtype 6a. The patient was infected with HCV subtype 6a. Prior to this case, there have been no previous reports on the isolation of this genotype/subtype from any other Iranian patient. Previous epidemiological studies provide valuable information about the distribution patterns of different HCV genotypes. However, infection with genotypes other than common ones should be flagged by specialists and diagnostic laboratories, especially in patients with high-risk behavioral backgrounds.