scholarly journals Disrupting the association of hepatitis C virus core protein with lipid droplets correlates with a loss in production of infectious virus

2007 ◽  
Vol 88 (8) ◽  
pp. 2204-2213 ◽  
Author(s):  
Steeve Boulant ◽  
Paul Targett-Adams ◽  
John McLauchlan

In infected cells, hepatitis C virus (HCV) core protein is targeted to lipid droplets, which serve as intracellular storage organelles. Using a tissue culture system to generate infectious HCV, we have shown that the coating of lipid droplets by the core protein occurs in a time-dependent manner and coincides with higher rates of virus production. At earlier times, the protein was located at punctate sites in close proximity to the edge of lipid droplets. Investigations by using Z-stack analysis have shown that many lipid droplets contained a single punctate site that could represent positions where core transfers from the endoplasmic reticulum membrane to droplets. The effects of lipid droplet association on virus production were studied by introducing mutations into the domain D2, the C-terminal region of the core protein necessary for droplet attachment. Alteration of a phenylalanine residue that was crucial for lipid droplet association generated an unstable form of the protein that could only be detected in the presence of a proteasome inhibitor. Moreover, converting two proline residues in D2 to alanines blocked coating of lipid droplets by core, although the protein was directed to punctate sites that were indistinguishable from those observed at early times for wild-type core protein. Neither of these virus mutants gave rise to virus progeny. By contrast, mutation at a cysteine residue positioned 2 aa upstream of the phenylalanine residue did not affect lipid droplet localization and produced wild-type levels of infectious progeny. Taken together, our findings indicate that lipid droplet association by core is connected to virus production.

2013 ◽  
Vol 88 (4) ◽  
pp. 1990-1999 ◽  
Author(s):  
S. Shi ◽  
X. Yu ◽  
Y. Gao ◽  
B. Xue ◽  
X. Wu ◽  
...  

2008 ◽  
Vol 82 (16) ◽  
pp. 7964-7976 ◽  
Author(s):  
Takahiro Masaki ◽  
Ryosuke Suzuki ◽  
Kyoko Murakami ◽  
Hideki Aizaki ◽  
Koji Ishii ◽  
...  

ABSTRACT Nonstructural protein 5A (NS5A) of the hepatitis C virus (HCV) possesses multiple and diverse functions in RNA replication, interferon resistance, and viral pathogenesis. Recent studies suggest that NS5A is involved in the assembly and maturation of infectious viral particles; however, precisely how NS5A participates in virus production has not been fully elucidated. In the present study, we demonstrate that NS5A is a prerequisite for HCV particle production as a result of its interaction with the viral capsid protein (core protein). The efficiency of virus production correlated well with the levels of interaction between NS5A and the core protein. Alanine substitutions for the C-terminal serine cluster in domain III of NS5A (amino acids 2428, 2430, and 2433) impaired NS5A basal phosphorylation, leading to a marked decrease in NS5A-core interaction, disturbance of the subcellular localization of NS5A, and disruption of virion production. Replacing the same serine cluster with glutamic acid, which mimics the presence of phosphoserines, partially preserved the NS5A-core interaction and virion production, suggesting that phosphorylation of these serine residues is important for virion production. In addition, we found that the alanine substitutions in the serine cluster suppressed the association of the core protein with viral genome RNA, possibly resulting in the inhibition of nucleocapsid assembly. These results suggest that NS5A plays a key role in regulating the early phase of HCV particle formation by interacting with core protein and that its C-terminal serine cluster is a determinant of the NS5A-core interaction.


Virology ◽  
2002 ◽  
Vol 292 (2) ◽  
pp. 198-210 ◽  
Author(s):  
Stephanie T. Shi ◽  
Stephen J. Polyak ◽  
Hong Tu ◽  
Deborah R. Taylor ◽  
David R. Gretch ◽  
...  

2008 ◽  
Vol 82 (15) ◽  
pp. 7624-7639 ◽  
Author(s):  
Yinghong Ma ◽  
Jeremy Yates ◽  
Yuqiong Liang ◽  
Stanley M. Lemon ◽  
MinKyung Yi

ABSTRACT A mutation within subdomain 1 of the hepatitis C virus (HCV) NS3 helicase (NS3-Q221L) (M. Yi, Y. Ma, J. Yates, and S. M. Lemon, J. Virol. 81:629-638, 2007) rescues a defect in production of infectious virus by an intergenotypic chimeric RNA (HJ3). Although NS3-Gln-221 is highly conserved across HCV genotypes, the Leu-221 substitution had no effect on RNA replication or NS3-associated enzymatic activities. However, while transfection of unmodified HJ3 RNA failed to produce either extracellular or intracellular infectious virus, transfection of HJ3 RNA containing the Q221L substitution (HJ3/QL) resulted in rapid accumulation of intracellular infectious particles with release into extracellular fluids. In the absence of the Q221L mutation, both NS5A and NS3 were recruited to core protein on the surface of lipid droplets, but there was no assembly of core into high-density, rapidly sedimenting particles. Further analysis demonstrated that a Q221N mutation minimally rescued virus production and led to a second-site I399V mutation in subdomain 2 of the helicase. Similarly, I399V alone allowed only low-level virus production and led to selection of an I286V mutation in subdomain 1 of the helicase which fully restored virus production, confirming the involvement of both major helicase subdomains in the assembly process. Thus, multiple mutations in the helicase rescue a defect in an early-intermediate step in virus assembly that follows the recruitment of NS5A to lipid droplets and precedes the formation of dense intracellular viral particles. These data reveal a previously unsuspected role for the NS3 helicase in early virion morphogenesis and provide a new perspective on HCV assembly.


2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Guan Qiang ◽  
Ravi Jhaveri

Background. Hepatitis C virus (HCV) genotype 3 is known to cause steatosis (fatty liver) that is more frequent and severe than other genotypes. We previously identified sequence elements within genotype 3 HCV Core domain 3 that were sufficient for lipid accumulation. Aims. We examined various genotype 3 Core domains for lipid droplet localization and compared the lipid droplet binding regions of domain 2 with a genotype 1 isolate. Methods. We generated HCV Core domain constructs fused with green fluorescent protein and performed immunofluorescence to visualize lipid droplets. Results. Constructs containing HCV Core domain 2 are appropriately localized to lipid droplets with varying degrees of efficiency. When compared to genotype 1, there are polymorphisms within domain 2 that do not appear to alter lipid droplet localization. Conclusions. In summary, the differences in a steatosis-associated HCV Core genotype 3 isolate do not appear to involve altered lipid droplet localization.


Virology ◽  
2014 ◽  
Vol 462-463 ◽  
pp. 166-174 ◽  
Author(s):  
Hiromichi Dansako ◽  
Hiroki Hiramoto ◽  
Masanori Ikeda ◽  
Takaji Wakita ◽  
Nobuyuki Kato

2010 ◽  
Vol 67 (18) ◽  
pp. 3151-3161 ◽  
Author(s):  
Marion Depla ◽  
Rustem Uzbekov ◽  
Christophe Hourioux ◽  
Emmanuelle Blanchard ◽  
Amélie Le Gouge ◽  
...  

Traffic ◽  
2008 ◽  
Vol 9 (8) ◽  
pp. 1268-1282 ◽  
Author(s):  
Steeve Boulant ◽  
Mark W. Douglas ◽  
Laura Moody ◽  
Agata Budkowska ◽  
Paul Targett-Adams ◽  
...  

2011 ◽  
Vol 54 ◽  
pp. S311 ◽  
Author(s):  
S. Clement ◽  
C. Fauvelle ◽  
S. Pascarella ◽  
S. Conzelmann ◽  
V. Kaddai ◽  
...  

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