Browsing by Author "Leon, Ursula"

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    Analysis of natural variants of the hepatitis C virus internal ribosome entry site reveals that primary sequence plays a key role in cap-independent translation
    (OXFORD UNIV PRESS, 2009) Ines Barria, Maria; Gonzalez, Angel; Vera Otarola, Jorge; Leon, Ursula; Vollrath, Valeska; Marsac, Delphine; Monasterio, Octavio; Perez Acle, Tomas; Soza, Alejandro; Lopez Lastra, Marcelo
    The HCV internal ribosome entry site (IRES) spans a region of similar to 340 nt that encompasses most of the 5' untranslated region (5'UTR) of the viral mRNA and the first 24-40 nt of the core-coding region. To investigate the implication of altering the primary sequence of the 5'UTR on IRES activity, naturally occurring variants of the 5'UTR were isolated from clinical samples and analyzed. The impact of the identified mutations on translation was evaluated in the context of RLuc/FLuc bicistronic RNAs. Results show that depending on their location within the RNA structure, these naturally occurring mutations cause a range of effects on IRES activity. However, mutations within subdomain IIId hinder HCV IRES-mediated translation. In an attempt to explain these data, the dynamic behavior of the subdomain IIId was analyzed by means of molecular dynamics (MD) simulations. Despite the loss of function, MD simulations predicted that mutant G266A/G268U possesses a structure similar to the wt-RNA. This prediction was validated by analyzing the secondary structure of the isolated IIId RNAs by circular dichroism spectroscopy in the presence or absence of Mg2+ ions. These data strongly suggest that the primary sequence of subdomain IIId plays a key role in HCV IRES-mediated translation.
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    Anaplasma platys in dogs, Chile
    (CENTER DISEASE CONTROL, 2007) Abarca, Katia; Lopez, Javier; Perret, Cecilia; Guerrero, Javier; Godoy, Paula; Veloz, Ana; Valiente Echeverria, Fernando; Leon, Ursula; Gutjahr, Constanza; Azocar, Teresa
    We conducted a 16S rRNA nested PCR for the genus Ehrlichia and Ehrlichia spp. with blood samples from 30 ill dogs in Chile. Phylogenetic analysis was performed by using groESL gene amplification. We identified Anaplasma platys as 1 of the etiologic agents of canine ehrlichiosis.
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    Influence of extrahepatic viral infection on the natural history of hepatitis C
    (ELSEVIER ESPANA, 2008) Ines Barria, Maria; Vera Otarola, Jorge; Leon, Ursula; Vollrath, Valeska; Marsac, Delphine; Riquelme, Arnoldo; Lopez Lastra, Marcelo; Soza, Alejandro
    HCV is primarily hepatotropic, but there is mounting evidence pointing to infection and replication of extrahepatic sites. Here we evaluated the occurrence of HCV infection of peripheral blood mononuclear cells (PBMC) and explored the possible association between viral extrahepatic infection and the natural history of the disease. Forty seven Chilean, HCV infected, treatment naive patients were included in the study. HCV RNA was isolated from plasma and PBMC and subsequently reverse transcribed, amplified and sequenced. Most patients harbored HCV 1b genotype and the most common route of infection showed to be blood transfusion. HCV RNA was readily detected in PBMCs of 34 out of the 47 patients (72%). We report that HCV sequences found in PBMC differ from those in plasma of the same subjects strongly suggesting HCV compartmentalization. In addition, we found that patients with detectable HCV RNA in PBMC had a tendency for being more likely cirrhotic [OR 3.8 (95 % CI: 0.98 to 14)]. In conclusion, this study provides further arguments for the existence of HCV infection of extrahepatic sites and suggests that extrahepatic infection could be a factor influencing the natural history of the disease.