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Dive into the research topics where Romuald Patient is active.

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Featured researches published by Romuald Patient.


Gut | 2007

The genotype 3-specific hepatitis C virus core protein residue phenylalanine 164 increases steatosis in an in vitro cellular model

Christophe Hourioux; Romuald Patient; Aurélie Morin; Emmanuelle Blanchard; Alain Moreau; Sylvie Trassard; Bruno Giraudeau; Philippe Roingeard

Background and aims: The prevalence and severity of liver steatosis are higher in patients infected with genotype 3 hepatitis C virus (HCV) than in patients infected with other genotypes. HCV core protein is known to affect lipid metabolism, inducing lipid droplet accumulation both in vitro and in vivo. An in vitro cellular model was used to investigate whether an HCV core protein with residues specific to genotype 3 increased this phenomenon. Methods: Sequence comparisons for HCV core protein domain II, which is known to interact with lipid droplets, identified the phenylalanine (F) residue at position 164 as the only residue specific to genotype 3. The area covered by lipid droplets in sections of cells producing a wild-type genotype 1a HCV core protein was compared with that in cells producing a Y164F mutant protein. Results: Cumulative lipid droplet area was significantly greater in sections of cells producing the Y164F mutant HCV core protein than in cells producing the wild-type protein (p<0.001). The frequency of cell sections containing more than 3 μm2 of lipid droplets, in particular, was higher for the mutant than for the wild-type protein. Conclusion: The data provide a molecular explanation for HCV genotype 3-specific lipid accumulation. This difference between genotypes may be due to phenylalanine having a higher affinity for lipids than tyrosine (Y). These observations provide useful information for further studies of the mechanisms involved in HCV-induced steatosis.


Cellular Microbiology | 2009

Morphogenesis of hepatitis B virus and its subviral envelope particles

Romuald Patient; Christophe Hourioux; Philippe Roingeard

After cell hijacking and intracellular amplification, non‐lytic enveloped viruses are usually released from the infected cell by budding across internal membranes or through the plasma membrane. The enveloped human hepatitis B virus (HBV) is an example of virus using an intracellular compartment to form new virions. Four decades after its discovery, HBV is still the primary cause of death by cancer due to a viral infection worldwide. Despite numerous studies on HBV genome replication little is known about its morphogenesis process. In addition to viral neogenesis, the HBV envelope proteins have the capability without any other viral component to form empty subviral envelope particles (SVPs), which are secreted into the blood of infected patients. A better knowledge of this process may be critical for future antiviral strategies. Previous studies have speculated that the morphogenesis of HBV and its SVPs occur through the same mechanisms. However, recent data clearly suggest that two different processes, including constitutive Golgi pathway or cellular machinery that generates internal vesicles of multivesicular bodies (MVB), independently form these two viral entities.


Journal of Virology | 2007

Hepatitis B Virus Subviral Envelope Particle Morphogenesis and Intracellular Trafficking

Romuald Patient; Christophe Hourioux; Pierre-Yves Sizaret; Sylvie Trassard; Camille Sureau; Philippe Roingeard

ABSTRACT Hepatitis B virus (HBV) is unusual in that its surface proteins (small [S], medium, and large [L]) are not only incorporated into the virion envelope but they also bud into empty subviral particles in great excess over virions. The morphogenesis of these subviral envelope particles remains unclear, but the S protein is essential and sufficient for budding. We show here that, in contrast to the presumed model, the HBV subviral particle formed by the S protein self-assembles into branched filaments in the lumen of the endoplasmic reticulum (ER). These long filaments are then folded and bridged for packing into crystal-like structures, which are then transported by ER-derived vesicles to the ER-Golgi intermediate compartment (ERGIC). Within the ERGIC, they are unpacked and relaxed, and their size and shape probably limits further progression through the secretory pathway. Such progression requires their conversion into spherical particles, which occurred spontaneously during the purification of these filaments by affinity chromatography. Small branched filaments are also formed by the L protein in the ER lumen, but these filaments are not packed into transport vesicles. They are transported less efficiently to the ERGIC, potentially accounting for the retention of the L protein within cells. These findings shed light on an important step in the HBV infectious cycle, as the intracellular accumulation of HBV subviral filaments may be directly linked to viral pathogenesis.


Cellular Microbiology | 2007

Core protein domains involved in hepatitis C virus-like particle assembly and budding at the endoplasmic reticulum membrane.

Christophe Hourioux; Malika Ait-Goughoulte; Romuald Patient; Delphine Fouquenet; Fabienne Arcanger-Doudet; Denys Brand; Annette Martin; Philippe Roingeard

Hepatitis C virus (HCV) core protein, expressed with a Semliki forest virus (SFV) replicon, self‐assembles into HCV‐like particles (HCV‐LPs) at the endoplasmic reticulum (ER) membrane, providing an opportunity to study HCV particle morphogenesis by electron microscopy. Various mutated HCV core proteins with engineered internal deletions were expressed with this system, to identify core domains required or dispensable for HCV‐LP assembly. The HCV core protein sequence was compared with its counterpart in GB virus B (GBV‐B), the virus most closely related to HCV, to identify conserved domains. GBV‐B and HCV display similar tropism for liver hepatocytes and their core proteins are organized similarly into three main domains (I, II and III), although GBV‐B core is smaller and lacks ∼35 amino acids (aa) in domain I. The deletion of short hydrophobic domains (aa 133–152 and 153–167 in HCV core) that appear highly conserved in domain II of both GBV‐B and HCV core proteins resulted in loss of HCV core ER anchoring and self‐assembly into HCV‐LPs. The deletion of short domains found within domain I of HCV core protein but not in the corresponding domain of GBV‐B core according to sequence alignment had contrasting effects. Amino acids 15–28 and 60–66 were shown to be dispensable for HCV‐LP assembly and morphogenesis, whereas aa 88–106 were required for this process. The production of GBV‐B core protein from a recombinant SFV vector was associated with specific ER ultrastructural changes, but did not lead to the morphogenesis of GBV‐B‐LPs, suggesting that different budding mechanisms occur in members of the Flaviviridae family.


New Biotechnology | 2009

Chimeric hepatitis B and C viruses envelope proteins can form subviral particles: implications for the design of new vaccine strategies

Romuald Patient; Christophe Hourioux; Pascal Vaudin; Jean-Christophe Pagès; Philippe Roingeard

The hepatitis B virus (HBV) envelope protein (S) self-assembles into subviral particles used as commercial vaccines against hepatitis B. These particles are excellent carriers for foreign epitopes, which can be inserted into the external hydrophilic loop or at the N- or C-terminal end of the HBV S protein. We show here that the N-terminal transmembrane domain (TMD) of HBV S can be replaced by the TMDs of the hepatitis C virus (HCV) envelope proteins E1 and E2, to generate fusion proteins containing the entire HCV E1 or E2 sequence that are efficiently coassembled with the HBV S into particles. This demonstrates the remarkable tolerance of the HBV S protein to sequence substitutions conserving its subviral particle assembly properties. These findings may have implications for the design of new vaccine strategies based on the use of HBV subviral particles as carriers for various transmembrane proteins and produced using the same industrial procedures that are established for the HBV vaccine.


Hepatology | 2013

Chimeric hepatitis B virus/hepatitis C virus envelope proteins elicit broadly neutralizing antibodies and constitute a potential bivalent prophylactic vaccine

Elodie Beaumont; Romuald Patient; Christophe Hourioux; Isabelle Dimier-Poisson; Philippe Roingeard

The development of a prophylactic vaccine against hepatitis C virus (HCV) has become an important medical priority, because 3‐4 million new HCV infections are thought to occur each year worldwide. Hepatitis B virus (HBV) is another major human pathogen, but infections with this virus can be prevented with a safe, efficient vaccine, based on the remarkable ability of the envelope protein (S) of this virus to self‐assemble into highly immunogenic subviral particles. Chimeric HBV‐HCV envelope proteins in which the N‐terminal transmembrane domain of S was replaced with the transmembrane domain of the HCV envelope proteins (E1 or E2) were efficiently coassembled with the wild‐type HBV S protein into subviral particles. These chimeric particles presented the full‐length E1 and E2 proteins from a genotype 1a virus in an appropriate conformation for formation of the E1‐E2 heterodimer. Produced in stably transduced Chinese hamster ovary cells and used to immunize New Zealand rabbits, these particles induced a strong specific antibody (Ab) response against the HCV and HBV envelope proteins in immunized animals. Sera containing anti‐E1 or anti‐E2 Abs elicited by these particles neutralized infections with HCV pseudoparticles and cell‐cultured viruses derived from different heterologous 1a, 1b, 2a, and 3 strains. Moreover, the anti–hepatitis B surface response induced by these chimeric particles was equivalent to the response induced by a commercial HBV vaccine. Conclusions: Our results provide support for approaches based on the development of bivalent HBV‐HCV prophylactic vaccine candidates potentially able to prevent initial infection with either of these two hepatotropic viruses. (HEPATOLOGY 2013)


Journal of General Virology | 2006

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

Malika Ait-Goughoulte; Christophe Hourioux; Romuald Patient; Sylvie Trassard; Denys Brand; Philippe Roingeard


Archive | 2009

NOVEL FUSION PROTEINS AND USE THEREOF FOR PREPARING HEPATITIS C VACCINES

Philippe Roingeard; Christophe Hourioux; Romuald Patient


Virologie | 2008

Morphogenèse du virus de l’hépatite B

Romuald Patient; C. Hourioux; Philippe Roingeard


Archive | 2017

NOVEL FUSION PROTEINS AND USE THEREOF FOR PREPARING VACCINES

Christophe Hourioux; Romuald Patient; Elodie Beaumont; Philippe Roingeard

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Christophe Hourioux

François Rabelais University

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Philippe Roingeard

François Rabelais University

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Sylvie Trassard

François Rabelais University

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Philippe Roingeard

François Rabelais University

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Denys Brand

François Rabelais University

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Elodie Beaumont

François Rabelais University

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Malika Ait-Goughoulte

François Rabelais University

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Pierre-Yves Sizaret

François Rabelais University

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Camille Sureau

Centre national de la recherche scientifique

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Alain Moreau

François Rabelais University

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