RESULTS:
1 - 4 of 4 for "Pilar Clemente-Casares"
Ubiquitin-like modifier-activating enzyme 1 interacts with Zika virus NS5 and promotes viral replication in the infected cell
Translation errors impaired folding or environmental stressors (e.g. infection) can all lead to an increase in the presence of misfolded proteins. These activate cellular responses to their removal including intracellular protein degradation activities. Protein ubiquitylation is involved in two major degradation pathways the ubiquitin-proteasome system and selective autophagy. In humans the ubiquitin-like modifier-activating enzyme 1 (UBA1) is the primary E1 enzyme in the ubiquitin conjugation cascade. Viruses have evolved to exploit protein degradation pathways to complete their infection cycles. Zika virus (ZIKV) is an emerging orthoflavivirus causing serious neurologic disorders in neonates (congenital microcephaly) and adults (Guillain–Barré syndrome). Non-structural protein 5 (NS5) the largest and most conserved protein in the orthoflaviviruses catalyses the synthesis and capping of new viral genomes. In addition to viral RNA replication in the cytoplasm ZIKV NS5 is translocated into the nucleus to interfere with host antiviral responses. Here we demonstrate that ZIKV NS5 co-immunoprecipitates with cellular UBA1. Immunofluorescence assays suggest that this interaction takes place primarily in the nucleus of an infected cell although colocalization of both proteins is also detected in the cytosol. RNA interference-mediated depletion of UBA1 leads to reduced virus titres in the infected cells while transient overexpression of UBA1 favours faster replication kinetics with higher virus titres and protein levels detected. Moreover UBA1-targeting drugs cause significant drops in virus infectivity. These results support a proviral role for UBA1 during ZIKV infection and encourage the potential use of inhibitors against this enzyme or its NS5-interacting epitopes as potential therapeutic targets.
Characterization of the interaction between hepatitis C virus NS5B and the human oestrogen receptor alpha
The RNA-dependent RNA polymerase (NS5B) of hepatitis C virus (HCV) is part of the viral replicative complex and plays a crucial role in HCV replication. It has been described that NS5B interacts with cellular proteins and that interactions between NS5B and host proteins are crucial for viral replication. Some of the host factors involved in the HCV replication cycle include the oestrogen receptor alpha (ESR1) protein kinases (c-Src) and chaperones (Hsp70). In this report we determine the requirements for the interplay between NS5B and the domain C of ESR1 (ESR1C) by using Förster Resonance Energy Transfer. NS5B–ESR1C and ESR1C–ESR1C interactions are dependent on ionic strength indicating that contacts are mainly electrostatic. Additionally NS5B residues involved in NS5B oligomerization were also essential for NS5B–ESR1C interaction. The study of the interactions among viral and host factors will provide data to establish innovative therapeutic strategies and the development of new antiviral drugs.
Putative neutralization epitopes and broad cross-genotype neutralization of Hepatitis E virus confirmed by a quantitative cell-culture assay
Monolayers of Hep G2/C3A cells were inoculated with genotype 1 Hepatitis E virus (HEV) mixed with either anti-HEV or an appropriate control. After 5 or 6 days cell monolayers were stained with anti-HEV and infected cells were identified by immunofluorescence microscopy and counted. Anti-HEV from vaccinated or infected rhesus monkeys neutralized the virus as did mAbs that recognized epitopes on the C terminus of a recombinant vaccine protein. Antibodies were broadly cross-reactive since convalescent serum from animals infected with any one of the four mammalian genotypes all neutralized the genotype 1 virus.
Genetic analysis of hepatitis A virus strains recovered from the environment and from patients with acute hepatitis
The molecular epidemiology of hepatitis A virus (HAV) was studied by analysing HAV strains recovered from environmental water samples over a 7 year period and strains recovered from patients with acute hepatitis over a 5 year period. A total of 54 samples of raw domestic sewage and 66 samples of river water were collected. HAV particles were concentrated and detected by nested RT–PCR. HAV infection in patients with acute hepatitis was serologically diagnosed in 26 of 74 serum samples which were also analysed by nested RT–PCR. HAV RNA was detected in 57·4% of sewage samples 39·2% of Llobregat river water samples 20% of Ter river water samples and 61·6% of serum samples. The HAV genomes detected were characterized further by directly sequencing a region of the 5′ non-translated region the VP1/2A junction region and in some samples the 2B region. Results showed a 95% prevalence of genotype I with nearly 50% being either subgenotype IA or subgenotype IB. Various strains were found simultaneously in both environmental and clinical samples. These strains were closely related to those described in distant geographical areas. Genotype IIIA was also found in 5% of sewage samples and in 12·5% of serum samples. Strains belonging to a common endemic genotype were not identified. The abundance of HAV in the environment produces a situation of sanitary risk especially considering the low prevalence of antibodies in the young population.