Biomedical subjects

Christophe Hourioux

Publications and source records attributed to Christophe Hourioux.

4 recordsLinked to original sources

PubMed2006

Core protein cleavage by signal peptide peptidase is required for hepatitis C virus-like particle assembly.

Hepatitis C virus (HCV) core protein, expressed with a Semliki Forest virus replicon, self-assembles into HCV-like particles (HCV-LP) at the endoplasmic reticulum (ER) membrane, providing an opportunity to study HCV assembly and morphogenesis by electron microscopy. This model was used to investigate whether the processing of the HCV core protein by the signal peptide peptidase (SPP) is required for the HCV-LP assembly. Several mutants were designed as there are conflicting reports concerning the cleavage of mutant proteins by SPP. Production of the only core mutant protein that escaped SPP processing led to the formation of multiple layers of electron-dense ER membrane, with no evidence of HCV-LP assembly. These data shed light on the HCV core residues involved in SPP cleavage and suggest that this cleavage is essential for HCV assembly.

Animals↗

PubMed2004

Hepatitis C virus ultrastructure and morphogenesis.

Details of the ultrastructure of hepatitis C virus (HVC) virion remain unclear because it has proved extremely difficult to visualise virus particles from infected serum and tissues directly. In addition, although much is known about the viral genome, first cloned in 1989, little is known about HCV morphogenesis, due to the lack of an efficient in vitro culture system for HCV propagation. Virus-like particles (VLPs) obtained by expressing genes encoding the HCV structural proteins in mammalian cells can be used as an alternative model for studying HCV morphogenesis. In particular, this HCV-LP model has made it possible to demonstrate that HCV budding occurs at the ER membrane and that the core protein drives this process. The HCV-LP model opens up new possibilities for the investigation of viral morphogenesis and virus-host cell interactions, which may make it possible to establish the long-awaited in vitro culture system for HCV.

Animals↗

PubMed2003

Hepatitis C virus-like particle budding: role of the core protein and importance of its Asp111.

In the absence of a hepatitis C virus (HCV) culture system, the use of a Semliki Forest virus replicon expressing genes encoding HCV structural proteins that assemble into HCV-like particles provides an opportunity to study HCV morphogenesis. Using this system, we showed that the HCV core protein constitutes the budding apparatus of the virus and that its targeting to the endoplasmic reticulum by means of the signal sequence of E1 protein is essential for budding. In addition, the aspartic acid at position 111 in the HCV core protein sequence was found to be crucial for virus assembly, demonstrating the usefulness of this system for mapping amino acids critical to HCV morphogenesis.

Animals↗

PubMed2002

In vitro expression of human hepatitis B virus genomes carrying woodchuck hepatitis virus pre-S1 sequences.

Many hepatitis B virus (HBV) in vivo experiments are unfeasible because this virus infects only humans. Former studies demonstrated that the pre-S1 domain of the viral envelope protein L determines host range. Therefore, we tried to generate HBV recombinants which might be able to infect woodchucks by exchanging different portions of the pre-S1 encoding gene with homologous parts from the related woodchuck hepatitis virus (WHV) in a cloned HBV genome. In 6 mutants, 11-92 N-terminal HBV pre-S1 codons were replaced by 20-120 codons from WHV. Four mutants carried C-terminal substitutions. The pre-S1 region overlaps with the viral polymerase gene, which is therefore also affected. After transfection of Huh7 cells, the DNA polymerase activity in cytoplasmic nucleocapsids was found to be only slightly affected. All mutants except for the largest C-terminal substitution allowed virion formation. Only the smallest N- and C-terminal substitutions had a wild-type phenotype. The remaining 7 variants allowed virion yields between 5 and 50% of that of the wild type. This demonstrated that substitution of up to 92 pre-S1 codons in an HBV genome with up to 120 codons from WHV pre- S1 was compatible with DNA replication and virion formation. Some recombinant viruses might be able to grow in woodchucks.

Amino Acid Sequence↗