Establishment of infectious genotype 4 cell culture-derived hepatitis C virus

HCV genome-wide analysis for development of efficient culture systems and unravelling of antiviral resistance in genotype 4

“…Recently, an ED43 infectious system was reported by Watanabe et al 29 This system was developed by using substitutions previously identified in ED43 replicons, 38 and the final ED43 virus could produce infectivity titres of ~3.5 log 10 FFU/mL after 39 days of infection. 29 Here, we report a different strategy, which is based on the use of substitutions conferring both viral Previously, we had succeeded in adapting genotypes 3a and 6a to efficiently grow in culture by initially combining substitutions identified in their corresponding C5A recombinants with changes in NS5B, which consisted of modifications of the sequence to reflect the consensus as compared with other genotypes 3a and 6a sequences, respectively. 3 4 However, for the original ED43, the NS5B sequence in the clone already reflected the consensus when compared with other deposited genotype 4a sequences.…”

“…[21][22][23] Efficient full-length infectious culture systems have been developed for selected strains of genotypes 1a, 2a, 2b, 3a and 6a after complex adaptation processes. 3 4 24-28 For genotype 4, a full-length cell culture system has recently been reported, but with limited propagation in Huh7.5 cells, 29 thus, a high titre system is still required for most studies on the viral life cycle, antivirals and vaccine development. Here, we aimed at developing a robust and efficient (high infectivity titre) full-length infectious system for HCV genotype 4a, permitting in-depth analysis of evolutionary networks underlying the emergence of DAA-resistance and assessments of the efficacy and barrier to resistance of clinically relevant DAA regimens.…”

Hepatitis C virus genotype 4: A poorly characterized endemic genotype

“…83 The introduction of these full-length constructs into Huh7.5.1 cells followed by a long-term passaging revealed additional mutations only for two clones releasing HCV core particles in the culture medium. 83 The latest GT4 full-length infectious clone is an ED43-based construct harboring a total of 32 mutations capable of promoting both replication and propagation mapped across the entire viral genome (except Core and P7) among which 5ʹ-UTR-G38A turned out to be paramount for substantial viral production in Huh7.5 cells. 58 Although the development of high replicative subgenomic replicon systems 71,72 has opened up avenues for the establishment of fully permissive cell culture systems; this hope was unfortunately abrogated when Pietschmann et al 84 demonstrated that the presence of REM mapped across the nonstructural region of the HCV genome are detrimental to virus production.…”

“…58,83 The first model system was established by constructing a full-length ED43 and several mutants harboring ED43's replication-enhancing mutations (REM). 83 The introduction of these full-length constructs into Huh7.5.1 cells followed by a long-term passaging revealed additional mutations only for two clones releasing HCV core particles in the culture medium. 83 The latest GT4 full-length infectious clone is an ED43-based construct harboring a total of 32 mutations capable of promoting both replication and propagation mapped across the entire viral genome (except Core and P7) among which 5ʹ-UTR-G38A turned out to be paramount for substantial viral production in Huh7.5 cells.…”

“…The first infectious full‐length HCV clone (HCVcc) termed JFH1 was established in 2005 from a GT2a isolate 79–81 . Attempts to develop infectious models for other genotypes and subtypes made very limited success and unlike JFH1, all other isolates require cell‐culture adaptation changes 82 as illustrated with the case of available GT4‐based HCVcc 58,83 . The first model system was established by constructing a full‐length ED43 and several mutants harboring ED43's replication‐enhancing mutations (REM) 83 .…”