Hepatitis C virus (HCV) replication requires annealing of a liver specific small-RNA, miR-122 to 2 sites on 5' untranslated region (UTR). Annealing has been reported to (a) stabilize the genome, (b) stimulate translation and (c) promote the formation of translationally active Internal Ribosome Entry Site (IRES) RNA structure. In this report, we map the RNA element to which small RNA annealing promotes HCV to nucleotides 1-44 and identify the relative impact of small RNA annealing on virus translation promotion and genome stabilization. We mapped the optimal region on the HCV genome to which small RNA annealing promotes virus replication to nucleotides 19-37 and found the efficiency of viral RNA accumulation decreased as annealing moved away from this region. Then, by using a panel of small RNAs that promote replication with varying efficiencies we link the efficiency of lifecycle promotion with translation stimulation. By contrast small RNA annealing stabilized the viral genome even if they did not promote virus replication. Thus, we propose that miR122 annealing promotes HCV replication by annealing to an RNA element that activates the HCV IRES and stimulates translation, and that miR-122 induced HCV genome stabilization is insufficient alone but enhances virus replication.

Background: Patients with chronic kidney failure and those undergoing chronic hemodialysis (CHD) treatment are at high risk of infection with hepatitis C virus (HCV). The incidence of occult HCV infection (OCI) in CHD remains controversial and the real burden of HCV in this population may be affected by the rate of OCI. This study evaluates the molecular assessment of OCI in CI-ID in an Iranian population. Methods: All subjects on CHD in the South Khorasan province of Iran were invited for participation in the study. Whole blood samples were taken and serological, clinical, and demographic information was recorded. HCV-RNAs were checked in serum and peripheral blood mononuclear cells (PBMCs) using an in-house semi-nested PCR assay. Viral load was determined using a real-time PCR-based quantification kit. Sequencing was performed to determine genotypes. Results: Overall, 120 cases participated in the study; 57.5% were male and the rest were female. In serum samples, no positive case was found for HCV-RNA. In PBMC samples, 2/120 (1.6%) were positive for HCV-RNA (95% CI, 0.002 to 0.059); the mean age of OCI positive cases was 37.5 +/- 19.2 years which was significantly lower than OCI negative cases (P = 0.026). Only one case had detectable viral load which was 49 IU/mL. The only HCV genotype identified was 1 a. Conclusion: This study showed that there is a risk of OCI among CHD patients; the very low and undetectable viral loads of OCI warrant further follow-up molecular testing for earlier diagnosis and treatment in the era of DAA.