scholarly journals Cell Culture Adaptation of Hepatitis C Virus and In Vivo Viability of an Adapted Variant

2007 ◽  
Vol 81 (23) ◽  
pp. 13168-13179 ◽  
Author(s):  
Artur Kaul ◽  
Ilka Woerz ◽  
Philip Meuleman ◽  
Geert Leroux-Roels ◽  
Ralf Bartenschlager
Keyword(s):  
Cell Culture ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Cultured Cells ◽  
Infectious Hepatitis ◽  
Adaptive Mutation ◽  
Viral Genomes ◽  
Adaptive Mutations ◽  
Spread Of Infection

ABSTRACT Production of infectious hepatitis C virus in cell culture has become possible because of the unique properties of the JFH1 isolate. However, virus titers are rather low, limiting the utility of this system. Here we describe the generation of cell culture-adapted JFH1 variants yielding higher titers of infectious particles and enhanced spread of infection in cultured cells. Sequence analysis of adapted genomes revealed a complex pattern of mutations that differed in two independent experiments. Adaptive mutations were observed both in the structural and in the nonstructural regions, with the latter having the highest impact on enhancement of virus titers. The major adaptive mutation was identified in NS5A, and it enhanced titers of three intergenotypic chimeras consisting of the structural region of a genotype 1a, 1b, or 3a isolate and the remainder of the JFH1 isolate. The mutation resides at the P3 position of the NS5A-B cleavage site and slows down processing, implying that subtle differences in replication complex formation appear to determine the efficiency of virus formation. Highly adapted JFH1 viruses carrying six mutations established a robust infection in uPA-transgenic SCID mice xenografted with human hepatocytes. However, the mutation in NS5A which enhanced virus titers in cell culture the most had reverted to wild type in nearly half of the viral genomes isolated from these animals at 15 weeks postinoculation. These results argue for some level of impaired fitness of this mutant in vivo.

scholarly journals Compensatory Mutations in E1, p7, NS2, and NS3 Enhance Yields of Cell Culture-Infectious Intergenotypic Chimeric Hepatitis C Virus

2006 ◽  
Vol 81 (2) ◽  
pp. 629-638 ◽  
Author(s):  
MinKyung Yi ◽  
Yinghong Ma ◽  
Jeremy Yates ◽  
Stanley M. Lemon
Keyword(s):  
Cell Culture ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Particle Production ◽  
Infectious Virus ◽  
Cultured Cells ◽  
Virus Assembly ◽  
Infectious Hepatitis ◽  
Adaptive Mutations ◽  
Compensatory Mutations

ABSTRACT There is little understanding of mechanisms underlying the assembly and release of infectious hepatitis C virus (HCV) from cultured cells. Cells transfected with synthetic genomic RNA from a unique genotype 2a virus (JFH1) produce high titers of virus, while virus yields are much lower with a prototype genotype 1a RNA containing multiple cell culture-adaptive mutations (H77S). To characterize the basis for this difference in infectious particle production, we constructed chimeric genomes encoding the structural proteins of H77S within the background of JFH1. RNAs encoding polyproteins fused at the NS2/NS3 junction (“H-NS2/NS3-J”) and at a site of natural, intergenotypic recombination within NS2 [“H-(NS2)-J”] produced infectious virus. In contrast, no virus was produced by a chimera fused at the p7-NS2 junction. Chimera H-NS2/NS3-J virus (vH-NS2/NS3-J) recovered from transfected cultures contained compensatory mutations in E1 and NS3 that were essential for the production of infectious virus, while yields of infectious vH-(NS2)-J were enhanced by mutations within p7 and NS2. These compensatory mutations were chimera specific and did not enhance viral RNA replication or polyprotein processing; thus, they likely compensate for incompatibilities between proteins of different genotypes at sites of interactions essential for virus assembly and/or release. Mutations in p7 and NS2 acted additively and increased the specific infectivity of vH-(NS2)-J particles, while having less impact on the numbers of particles released. We conclude that interactions between NS2 and E1 and p7 as well as between NS2 and NS3 are essential for virus assembly and/or release and that each of these viral proteins plays an important role in this process.

scholarly journals Efficient Infectious Cell Culture Systems of the Hepatitis C Virus (HCV) Prototype Strains HCV-1 and H77

2014 ◽  
Vol 89 (1) ◽  
pp. 811-823 ◽  
Author(s):  
Yi-Ping Li ◽  
Santseharay Ramirez ◽  
Lotte Mikkelsen ◽  
Jens Bukh
Keyword(s):  
Cell Culture ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Adaptive Mutations ◽  
Culture Systems ◽  
Infectious Clones ◽  
Cell Culture Systems ◽  
A Genome

ABSTRACTThe first discovered and sequenced hepatitis C virus (HCV) genome and the firstin vivoinfectious HCV clones originated from the HCV prototype strains HCV-1 and H77, respectively, both widely used in research of this important human pathogen. In the present study, we developed efficient infectious cell culture systems for these genotype 1a strains by using the HCV-1/SF9_A and H77Cin vivoinfectious clones. We initially adapted a genome with the HCV-1 5′UTR-NS5A (where UTR stands for untranslated region) and the JFH1 NS5B-3′UTR (5-5A recombinant), including the genotype 2a-derived mutations F1464L/A1672S/D2979G (LSG), to grow efficiently in Huh7.5 cells, thus identifying the E2 mutation S399F. The combination of LSG/S399F and reported TNcc(1a)-adaptive mutations A1226G/Q1773H/N1927T/Y2981F/F2994S promoted adaptation of the full-length HCV-1 clone. An HCV-1 recombinant with 17 mutations (HCV1cc) replicated efficiently in Huh7.5 cells and produced supernatant infectivity titers of 104.0focus-forming units (FFU)/ml. Eight of these mutations were identified from passaged HCV-1 viruses, and the A970T/I1312V/C2419R/A2919T mutations were essential for infectious particle production. Using CD81-deficient Huh7 cells, we further demonstrated the importance of A970T/I1312V/A2919T or A970T/C2419R/A2919T for virus assembly and that the I1312V/C2419R combination played a major role in virus release. Using a similar approach, we found that NS5B mutation F2994R, identified here from culture-adapted full-length TN viruses and a common NS3 helicase mutation (S1368P) derived from viable H77C and HCV-1 5-5A recombinants, initiated replication and culture adaptation of H77C containing LSG and TNcc(1a)-adaptive mutations. An H77C recombinant harboring 19 mutations (H77Ccc) replicated and spread efficiently after transfection and subsequent infection of naive Huh7.5 cells, reaching titers of 103.5and 104.4FFU/ml, respectively.IMPORTANCEHepatitis C virus (HCV) was discovered in 1989 with the cloning of the prototype strain HCV-1 genome. In 1997, two molecular clones of H77, the other HCV prototype strain, were shown to be infectious in chimpanzees, but notin vitro. HCV research was hampered by a lack of infectious cell culture systems, which became available only in 2005 with the discovery of JFH1 (genotype 2a), a genome that could establish infection in Huh7.5 cells. Recently, we developedin vitroinfectious clones for genotype 1a (TN), 2a (J6), and 2b (J8, DH8, and DH10) strains by identifying key adaptive mutations. Globally, genotype 1 is the most prevalent. Studies using HCV-1 and H77 prototype sequences have generated important knowledge on HCV. Thus, thein vitroinfectious clones developed here for these 1a strains will be of particular value in advancing HCV research. Moreover, our findings open new avenues for the culture adaptation of HCV isolates of different genotypes.

scholarly journals Amino Acid Mutations in the NS4A Region of Hepatitis C Virus Contribute to Viral Replication and Infectious Virus Production

2016 ◽  
Vol 91 (4) ◽  
Author(s):  
Asako Murayama ◽  
Nao Sugiyama ◽  
Ryosuke Suzuki ◽  
Masaki Moriyama ◽  
Noriko Nakamura ◽  
...  
Keyword(s):  
Cell Culture ◽  
Hepatitis C ◽  
Culture System ◽  
Infectious Virus ◽  
Cultured Cells ◽  
Virus Production ◽  
Adaptive Mutation ◽  
Cell Culture System ◽  
Adaptive Mutations ◽  
Amino Acid Mutations

ABSTRACT Hepatitis C virus (HCV) strain JFH-1, which belongs to genotype 2a, replicates autonomously in cultured cells, whereas another genotype 2a strain, J6CF, does not. Previously, we found that replacement of the NS3 helicase and NS5B-to-3′X regions of J6CF with those of JFH-1 confers J6CF replication competence. In this study, we aimed to identify the minimum modifications within these genomic regions needed to establish replication-competent J6CF. We previously identified 4 mutations in the NS5B-to-3′X region that could be used instead of replacement of this region to confer J6CF replication competence. Here, we induced cell culture-adaptive mutations in J6CF by the long-term culture of J6CF/JFH-1 chimeras composed of JFH-1 NS5B-to-3′X or individual parts of this but not the NS3 helicase region. After 2 months of culture, efficient HCV replication and infectious virus production in chimeric RNA-transfected cells were observed, and several amino acid mutations in NS4A were identified in replicating HCV genomes. The introduction of NS4A mutations into the J6CF/JFH-1 chimeras enhanced viral replication and infectious virus production. Immunofluorescence microscopy demonstrated that some of these mutations altered the subcellular localization of the coexpressed NS3 protein and affected the interaction between NS3 and NS4A. Finally, introduction of the most effective NS4A mutation, A1680E, into J6CF contributed to its replication competence in cultured cells when introduced in conjunction with four previously identified adaptive mutations in the NS5B-to-3′X region. In conclusion, we identified an adaptive mutation in NS4A that confers J6CF replication competence when introduced in conjunction with 4 mutations in NS5B-to-3′X and established a replication-competent J6CF strain with minimum essential modifications in cultured cells. IMPORTANCE The HCV cell culture system using the JFH-1 strain and HuH-7 cells can be used to assess the complete HCV life cycle in cultured cells. This cell culture system has been used to develop direct-acting antivirals against HCV, and the ability to use various HCV strains within this system is important for future studies. In this study, we aimed to establish a novel HCV cell culture system using another HCV genotype 2a strain, J6CF, which replicates in chimpanzees but not in cultured cells. We identified an effective cell culture-adaptive mutation in NS4A and established a replication-competent J6CF strain in cultured cells with minimum essential modifications. The described strategy can be used in establishing a novel HCV cell culture system, and the replication-competent J6CF clone composed of the minimum essential modifications needed for cell culture adaptation will be valuable as another representative of genotype 2a strains.

scholarly journals Analysis of hepatitis C virus core/NS5A protein co-localization using novel cell culture systems expressing core–NS2 and NS5A of genotypes 1–7

2013 ◽  
Vol 94 (10) ◽  
pp. 2221-2235 ◽  
Author(s):  
Andrea Galli ◽  
Troels K. H. Scheel ◽  
Jannick C. Prentoe ◽  
Lotte S. Mikkelsen ◽  
Judith M. Gottwein ◽  
...  
Keyword(s):  
Cell Culture ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Current Knowledge ◽  
Particle Assembly ◽  
Adaptive Mutations ◽  
Culture Systems ◽  
The Core ◽  
Cell Culture Systems ◽  
Significant Difference

Hepatitis C virus (HCV) is an important human pathogen infecting hepatocytes. With the advent of infectious cell culture systems, the HCV particle assembly and release processes are finally being uncovered. The HCV core and NS5A proteins co-localize on cytoplasmic lipid droplets (cLDs) or on the endoplasmic reticulum (ER) at different stages of particle assembly. Current knowledge on assembly and release is primarily based on studies in genotype 2a cell culture systems; however, given the high genetic heterogeneity of HCV, variations might exist among genotypes. Here, we developed novel HCV strain JFH1-based recombinants expressing core–NS2 and NS5A from genotypes 1–7, and analysed core and NS5A co-localization in infected cells. Huh7.5 cells were transfected with RNA of core–NS2/NS5A recombinants and putative adaptive mutations were analysed by reverse genetics. Adapted core–NS2/NS5A recombinants produced infectivity titres of 102.5–104.5 f.f.u. ml−1. Co-localization analysis demonstrated that the core and NS5A proteins from all genotypes co-localized extensively, and there was no significant difference in protein co-localization among genotypes. In addition, we found that the core and NS5A proteins were highly associated with cLDs at 12 h post-infection but became mostly ER associated at later stages. Finally, we found that different genotypes showed varying levels of core/cLD co-localization, with a possible effect on viral assembly/release. In summary, we developed a panel of HCV genotype 1–7 core–NS2/NS5A recombinants producing infectious virus, and an immunostaining protocol detecting the core and NS5A proteins from seven different genotypes. These systems will allow, for the first time, investigation of core/NS5A interactions during assembly and release of HCV particles of all major genotypes.

scholarly journals Enhancement of Hepatitis C Virus RNA Replication by Cell Culture-Adaptive Mutations

2001 ◽  
Vol 75 (10) ◽  
pp. 4614-4624 ◽  
Author(s):  
Nicole Krieger ◽  
Volker Lohmann ◽  
Ralf Bartenschlager
Keyword(s):  
Cell Culture ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Colony Formation ◽  
Marker Gene ◽  
Rna Replication ◽  
Clear Correlation ◽  
Transfected Cells ◽  
Adaptive Mutations ◽  
Selection Of

ABSTRACT Studies of the Hepatitis C virus (HCV) replication cycle have been made possible with the development of subgenomic selectable RNAs that replicate autonomously in cultured cells. In these replicons the region encoding the HCV structural proteins was replaced by the neomycin phosphotransferase gene, allowing the selection of transfected cells that support high-level replication of these RNAs. Subsequent analyses revealed that, within selected cells, HCV RNAs had acquired adaptive mutations that increased the efficiency of colony formation by an unknown mechanism. Using a panel of replicons that differed in their degrees of cell culture adaptation, in this study we show that adaptive mutations enhance RNA replication. Transient-transfection assays that did not require selection of transfected cells demonstrated a clear correlation between the level of adaptation and RNA replication. The highest replication level was found with an adapted replicon carrying two amino acid substitutions located in NS3 and one in NS5A that acted synergistically. In contrast, the nonadapted RNA replicated only transiently and at a low level. The correlation between the efficiency of colony formation and RNA replication was corroborated with replicons in which the selectable marker gene was replaced by the gene encoding firefly luciferase. Upon transfection of naive Huh-7 cells, the levels of luciferase activity directly reflected the replication efficiencies of the various replicon RNAs. These results show that cell culture-adaptive mutations enhance HCV RNA replication.

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