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Temporal variations in the hepatitis C virus intrahost population during chronic infection.

ABSTRACT: The intrahost evolution of hepatitis C virus (HCV) holds keys to understanding mechanisms responsible for the establishment of chronic infections and to development of a vaccine and therapeutics. In this study, intrahost variants of two variable HCV genomic regions, HVR1 and NS5A, were sequenced from four treatment-naïve chronically infected patients who were followed up from the acute stage of infection for 9 to 18 years. Median-joining network analysis indicated that the majority of the HCV intrahost variants were observed only at certain time points, but some variants were detectable at more than one time point. In all patients, these variants were found organized into communities or subpopulations. We hypothesize that HCV intrahost evolution is defined by two processes: incremental changes within communities through random mutation and alternations between coexisting communities. The HCV population was observed to incrementally evolve within a single community during approximately the first 3 years of infection, followed by dispersion into several subpopulations. Two patients demonstrated this pattern of dispersion for the rest of the observation period, while HCV variants in the other two patients converged into another single subpopulation after ?9 to 12 years of dispersion. The final subpopulation in these two patients was under purifying selection. Intrahost HCV evolution in all four patients was characterized by a consistent increase in negative selection over time, suggesting the increasing HCV adaptation to the host late in infection. The data suggest specific staging of HCV intrahost evolution.

SUBMITTER: Ramachandran S

PROVIDER: S-EPMC3126498 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature

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Temporal variations in the hepatitis C virus intrahost population during chronic infection.

Ramachandran Sumathi S Campo David S DS Dimitrova Zoya E ZE Xia Guo-liang GL Purdy Michael A MA Khudyakov Yury E YE

Journal of virology 20110427 13

The intrahost evolution of hepatitis C virus (HCV) holds keys to understanding mechanisms responsible for the establishment of chronic infections and to development of a vaccine and therapeutics. In this study, intrahost variants of two variable HCV genomic regions, HVR1 and NS5A, were sequenced from four treatment-naïve chronically infected patients who were followed up from the acute stage of infection for 9 to 18 years. Median-joining network analysis indicated that the majority of the HCV in ...[more]

PMID: 21525348

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Project description:Hepatitis B virus (HBV) infection is a leading cause of liver diseases including cirrhosis and hepatocellular carcinoma. Human leukocyte antigens (HLAs) play an important role in the regulation of immune response against infectious organisms, including HBV. Recently, several genome-wide association (GWAS) studies have shown that genetic variations in HLA genes influence disease progression in HBV infection. The aim of this study was to investigate the role of HLA genetic polymorphisms and their possible role in HBV infection in Saudi Arabian patients. Variations in HLA genes were screened in 1672 subjects who were divided according to their clinical status into six categories as follows; clearance group, inactive carriers, active carriers, cirrhosis, hepatocellular carcinoma (HCC) patients and uninfected healthy controls. Three single nucleotide polymorphisms (SNPs) belonged to HLA-DQ region (rs2856718, rs7453920 and rs9275572) and two SNPs belonged to HLA-DP (rs3077 and rs9277535) were studied. The SNPs were genotyped by PCR-based DNA sequencing (rs2856718) and allele specific TaqMan genotyping assays (rs3077, rs7453920, rs9277535 and rs9275572). The results showed that rs2856718, rs3077, rs9277535 and rs9275572 were associated with HBV infection (p = 0.0003, OR = 1.351, CI = 1.147-1.591; p = 0.041, OR = 1.20, CI = 1.007-1.43; p = 0.045, OR = 1.198, CI = 1.004-1.43 and p = 0.0018, OR = 0.776, CI = 0.662-0.910, respectively). However, allele frequency of rs2856718, rs7453920 and rs9275572 were found more in chronically infected patients when compared to clearance group infection (p = 0.0001, OR = 1.462, CI = 1.204-1.776; p = 0.0178, OR = 1.267, CI = 1.042-1.540 and p = 0.010, OR = 0.776, CI = 0.639-0.942, respectively). No association was found when polymorphisms in HLA genes were compared in active carriers versus cirrhosis/HCC patients. In conclusion, these results suggest that variations in HLA genes could affect susceptibility to and clearance of HBV infection in Saudi Arabian patients.

Project description:UnlabelledHepatitis C virus (HCV) causes chronic infection in up to 50% to 80% of infected individuals. Hypervariable region 1 (HVR1) variability is frequently studied to gain an insight into the mechanisms of HCV adaptation during chronic infection, but the changes to and persistence of HCV subpopulations during intrahost evolution are poorly understood. In this study, we used ultradeep pyrosequencing (UDPS) to map the viral heterogeneity of a single patient over 9.6 years of chronic HCV genotype 4a infection. Informed error correction of the raw UDPS data was performed using a temporally matched clonal data set. The resultant data set reported the detection of low-frequency recombinants throughout the study period, implying that recombination is an active mechanism through which HCV can explore novel sequence space. The data indicate that polyvirus infection of hepatocytes has occurred but that the fitness quotients of recombinant daughter virions are too low for the daughter virions to compete against the parental genomes. The subpopulations of parental genomes contributing to the recombination events highlighted a dynamic virome where subpopulations of variants are in competition. In addition, we provide direct evidence that demonstrates the growth of subdominant populations to dominance in the absence of a detectable humoral response.ImportanceAnalysis of ultradeep pyrosequencing data sets derived from virus amplicons frequently relies on software tools that are not optimized for amplicon analysis, assume random incorporation of sequencing errors, and are focused on achieving higher specificity at the expense of sensitivity. Such analysis is further complicated by the presence of hypervariable regions. In this study, we made use of a temporally matched reference sequence data set to inform error correction algorithms. Using this methodology, we were able to (i) detect multiple instances of hepatitis C virus intrasubtype recombination at the E1/E2 junction (a phenomenon rarely reported in the literature) and (ii) interrogate the longitudinal quasispecies complexity of the virome. Parallel to the UDPS, isolation of IgG-bound virions was found to coincide with the collapse of specific viral subpopulations.

Project description:BACKGROUND: Variations at DEPDC5 gene have been recently reported as genetic markers associated with hepatocellular carcinoma (HCC) progression in chronic HCV-infected patients. This study was conducted to assess the association of DEPDC5 variants with advanced liver cirrhosis and HCC development among chronic HCV-infected patients in Saudi Arabian population. METHODS: Six-hundred and one HCV-infected patients were genotyped for DEPDC5 polymorphisms (rs1012068 and rs5998152), in comparison with 592 non-infected healthy control subjects. The allelic frequency and genotype distribution of both DEPDC5 polymorphisms were determined followed by haplotype frequency estimation and multiple logistic regression analysis. RESULTS: The frequency of the risk alleles of both rs1012068 and rs5998152 was shown to be more in healthy control subjects than in patients (p = 0.0001, OR = 0.704, CI = 0.591-0.839; p = 0.002, OR = 0.761, CI = 0. 0.639-0.907, respectively). Also, our results revealed that GT for SNP rs1012068 (OR =1.715; 95% CI 1.132-2.597; p = 0.0104) and CT for SNP rs5998152 (OR = 1.932; 95% CI 1.276-2.925; p = 0.0017) showed significant association with development of cirrhosis compared with the GG and CC genotypes, respectively. The data also revealed that subjects with the T allele of both SNPs appeared to have a lower susceptibility to HCV-related cirrhosis/HCC than those with the G allele of rs1012068 (p = 0.038, OR = 1.353, 95 % CI 1.017-1.800) and C allele of rs5998152 (p = 0.043, OR = 1.342, 95 % CI 1.010-1.784). Haplotype analysis showed that a combination of T-T alleles of rs1012068 and rs5998152 was significantly associated with liver cirrhosis (frequency = 71.3% and p = 0.027) and with cirrhosis/HCC (frequency = 71.4% and P = 0.045). Also, multiple logistic regression analysis showed that rs5998152 (OR = 2.844, 95% CI 1.333-6.069 and p = 0.007), rs1012068 (OR = 2.793, 95% CI 1.316-5.928 and p = 0.010), age (OR = 1.029, 95% CI 1.001-1.057 and p = 0.041) and HCV genotypes (OR = 0.247, 95% CI 0.097-0.630 and p = 0.003) were independently associated with chronicity of HCV infection. CONCLUSION: Genetic variations in DEPDC5 gene region may influence HCV-associated liver cirrhosis and/or HCC development.

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Temporal variations in the hepatitis C virus intrahost population during chronic infection.

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Temporal variations in the hepatitis C virus intrahost population during chronic infection.

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