GCRIS

Hepatitis C virus (HCV) is a globally-dispersed agent of chronic hepatitis with a significant public health threat, affecting over 110 million individuals throughout the world. The increased risk for chronicity after exposure and the lack of a protective vaccine make HCV is a leading infectious cause of cirrhosis, liver failure requiring transplantation and hepatocellular carcinoma. The replicative process and infection dynamics in the host enable HCV to generate an array of closely-related but non-identical genetic variants known as quasispecies in the infected individuals. Pathogenesis and outcome in HCV infections are directly affected by the virus genetic heterogeneity, reflected as the emergence of quasispecies in infected individuals. The evolution of these highly-diverse viral populations in the host directly influences the disease course, via providing a pool of variants capable of resuming viral replication under extrinsic and/or intrinsic selective pressures. Viral quasispecies go through several alterations during the course of the infection, and provide a background for the selection of escape mutants from the host humoral and cell-mediated immune responses and antiviral treatment. Supported by the robust next generation sequencing techniques, recent studies have provided significant insights on the genomic diversity and progression as well as on the origin and the epidemiology of HCV. This review provides an overview of the mechanisms of HCV genetic variability, and the interactions with the host, that affects clinical disease, covering viral and host determinants of humoral and cell-mediated immune responses, alterations during the early and late stages of the infection and disease progression leading to chronicity. In addition, current findings in virus evolution and epidemiology were briefly interpreted from the inter-species and population perspectives. The impact of viral genomic heterogeneity on antiviral treatment in the era of direct-acting agents is also discussed, along with an overview of current methods employed for the characterization of viral diversity.

G-Quadruplexes, a class of noncanonical but highly stable nucleic acid structures, have the potential to be part of the regulatory mechanism of cells. They can form in the genome where the double-stranded helix is unwound to facilitate formation of a G-quadruplex. The biological significance of these structures is yet to be understood entirely. This work presents a novel approach and investigates common characteristics in the distribution of G-quadruplexes relative to genes in plants through analysis of genomes and gene expressions. The results indicate that G-quadruplex distribution has gone through significant changes with the evolution of higher plants and, for the first tune, that G-quadruplexes enriched at the beginning of introns may have a regulatory role during transcription.

TR Dizin İndeksli Yayınlar Koleksiyonu / TR Dizin Indexed Publications Collection

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