Unconjugated
Previously, RNA transcripts of cDNA clones of hepatitis C virus (HCV) genotypes 1a (strains H77, HCV-1, and HC-TN), 1b (HC-J4, Con1, and HCV-N), and 2a (HC-J6 and JFH1) were found to be infectious in chimpanzees. However, only JFH1 was infectious in human hepatoma Huh7 cells. We performed genetic analysis of HCV genotype 3a (strain S52) and 4a (strain ED43) prototype strains and generated full-length consensus cDNA clones (pS52 and pED43). Transfection of Huh7.5 cells with RNA transcripts of these clones did not yield cells expressing HCV Core. However, intrahepatic transfection of chimpanzees resulted in robust infection with peak HCV RNA titers of approximately 5.5 log(10) international units (IU)/ml. Genomic consensus sequences recovered from serum at the times of peak viral titers were identical to the sequences of the parental plasmids. Both chimpanzees developed acute hepatitis with elevated liver enzymes and significant necroinflammatory liver changes coinciding with detection of gamma interferon-secreting, intrahepatic T cells. However, the onset and broadness of intrahepatic T-cell responses varied greatly in the two animals, with an early (week 4) multispecific response in the ED43-infected animal (3 weeks before the first evidence of viral control) and a late (week 11) response with limited breadth in the S52-infected animal (without evidence of viral control). Autologous serum neutralizing antibodies were not detected during the acute infection in either animal. Both animals became persistently infected. In conclusion, we generated fully functional infectious cDNA clones of HCV genotypes 3a and 4a. Proof of functionality of all genes might further the development of recombinant cell culture systems for these important genotypes.
Dendritic cells (DCs) are reported to be functionally deficient during chronic hepatitis C virus (HCV) infection. Differing results have been reported on direct effects of intact replicative-form HCV on DC function. To better understand the effect of HCV on DC function, we treated freshly purified human myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) with HCV JFH1. We found that HCV upregulated mDC maturation marker (CD83, CD86, and CD40) expression and did not inhibit Toll-like receptor 3 (TLR3) ligand [poly(I:C)]-induced mDC maturation, a finding consistent with the phenotype of DCs from HCV-infected subjects. At the same time, HCV JFH1 inhibited the ability of poly(I:C)-treated mDCs to activate naive CD4 T cells. In contrast, although there was no direct effect of virus on pDC maturation, HCV JFH1 inhibited TLR7 ligand (R848)-induced pDC CD40 expression, and this was associated with impaired ability to activate naive CD4 T cells. Parallel experiments with recombinant HCV proteins indicated HCV core protein may be responsible for a portion of the activity. Furthermore, HCV-mediated mDC maturation was dependent upon CD81-E2 interaction and, in part, TLR2. Using UV-treated HCV, we show that HCV-mediated mDC and pDC maturation is virus replication independent and, using strand specific PCR, we found no evidence for HCV replication within DCs. Because these effects of HCV on DC subset maturation and function in part recapitulate direct ex vivo analysis of DCs in chronic HCV infection, the mechanisms described here likely account for a portion of the DC subset defects observed in vivo.