Molecular characterization of hepatitis C virus in end-stage renal disease patients under hemodialysis.

New direct-acting antiviral (DAA) agents are in development or already approved for the treatment of chronic hepatitis C virus (HCV) infection. The effectiveness of these drugs is related to the previous existence of resistant variants. Certain clinical conditions can allow changes in immunological characteristics of the host and even modify genetic features of viral populations. The aim of this study was to perform HCV molecular characterization from samples of end-stage renal disease patients on hemodialysis (ESRD-HD). Nested PCR and Sanger sequencing were used to obtain genetic information from the NS5B partial region of a cohort composed by 86 treatment-naïve patients. Genomic sequences from the Los Alamos databank were employed for comparative analysis. Bioinformatics methodologies such as phylogenetic reconstructions, informational entropy, and mutation analysis were used to analyze datasets separated by geographical location, HCV genotype, and renal function status. ESRD-HD patients presented HCV genotypes 1a (n = 18), 1b (n = 16), 2a (n = 2), 2b (n = 2), and 3a (n = 4). Control subjects were infected with genotypes 1a (n = 11), 1b (n = 21), 2b (n = 4), and 3a (n = 8). Dataset phylogenetic reconstruction separated HCV subtype 1a into two distinct clades. The entropy analysis from the ESRD-HD group revealed two amino acid positions related to an epitope for cytotoxic T lymphocytes and T helper cells. Genotype 1a was found to be more diverse than subtype 1b. Also, genotype 1a ERSD-HD patients had a higher mean of amino acids changes in comparison to control group patients. The identification of specific mutations on epitopes and high genetic diversity within the NS5B HCV partial protein in hemodialysis patients can relate to host immunological features and geographical distribution patterns. This genetic diversity can affect directly the new DAA's resistance mechanisms.

Evidence of bottleneck effect on hepatitis C virus transmission between a couple under interferon based therapy.

Issues on the correlation of viral genetic diversity and treatment response to the hepatitis C infection remain uncertain. The bottleneck effect dictates the characteristics of the viral population that will establish the infection in a new host and is related to how the immune system and treatment will be effective against the virus. Here we evaluated the phylogenetic characteristics of quasispecies population and the treatment response pattern of a HCV infected couple. We also analyzed whether the viral population of these patients indicated that they were exposed to the same source for primer infection. This study included two patients (P10 and P11) HCV genotype 1b infected. The couple presented horizontal transmission. Viral RNA was isolated from serum samples collected before, during and after treatment, at specific time points. The HCV NS5A gene sequence was amplified, cloned and sequenced. Genetic and evolutionary analyses were performed to compare the quasispecies population of these two patients and local control patients. Genetic distance and diversity were calculated. Phylogenetic analyses were performed by using maximum likelihood and Bayesian methodologies. The analysis of the baseline samples showed that the genetic distance of the viral populations of patients P10 and P11 was significantly lower than when these patients and the control group based on sequences from local patients were analyzed, supporting the horizontal transmission hypothesis. Phylogenetic analysis with sequences from all the time point samples also demonstrated two patterns of evolution depending on the treatment response. The Bayesian analysis showed that one isolate corresponding to the baseline sample of P10 was grouped into the P11 clade, suggesting a way of infection and a bottleneck effect. Our data suggests that the patient P11 viral population may be originated from variants from P10 patient and consequently showing that clinical differences between treatment responses can emerge from the bottleneck effect on viral populations.