Differences in hepatitis C virus (HCV) variants of the highly conserved 5 untranslated region (UTR) have been observed between plasma and peripheral blood mononuclear cells (PBMC). The prevalence and the mechanisms of this compartmentalization are unknown. Plasma and PBMC HCV variants were compared by single-strand conformation polymorphism (SSCP) and by cloning or by genotyping with a line probe assay (LiPA) in 116 chronically infected patients, including 44 liver transplant recipients. SSCP patterns differed between compartments in 43/109 analyzable patients (39%). Differences were significantly more frequent in patients with transplants (21/38 [55%] versus 22/71 [31%]; P < 0.01) and in those who acquired HCV through multiple transfusions before 1991 (15/20; 75%) or through drug injection (16/31; 52%) than in those infected through an unknown route (7/29; 24%) or through a single transfusion (5/29; 17%; P < 0.001). Cloning of the 5 UTR, LiPA analysis, and nonstructural region 5B sequencing revealed different genotypes in the two compartments from 10 patients (9%). In nine patients, the genotype detected in PBMC was not detected in plasma and was weak or undetectable in the liver in three cases. This genotypic compartmentalization persisted for years in three patients and after liver transplantation in two. The present study shows that a significant proportion of HCV-infected subjects harbor in their PBMC highly divergent variants which were likely acquired through superinfections.Hepatitis C virus (HCV) frequently leads to chronic infection contributing to liver cirrhosis and hepatocellular carcinoma. HCV is an enveloped, positive-stranded RNA virus that circulates in vivo as a population of closely related variants collectively referred to as a quasispecies. This quasispecies nature may be involved in viral persistence at the early stages of infection (12), allowing the emergence of immune escape mutants (11, 13). The infection of immune cells could be another viral mechanism of evasion contributing to host failure in eradicating the virus (32). The issue of extrahepatic replication of HCV is still debated. Detection of HCV RNA in extrahepatic compartments can be due to the adsorption of plasma variants (17, 31). However, the minus-stranded HCV RNA, the replicative intermediate, which is not detected in plasma, has been detected in peripheral blood mononuclear cells (PBMC) in many studies (4,8,10,15,18,21,22,23,25,28,37), but this is not sufficient to demonstrate that a complete and productive replication of HCV really occurs in these cells.Another point supporting autonomous HCV replication in PBMC is the common finding in these cells of HCV variants differing from those circulating in serum (26, 31). The study of different blood cell subsets also revealed that quasispecies compositions can differ significantly between peripheral B and T lymphocytes, monocytes, and plasma (1). We have recently shown that this compartmentalization is a frequent phenomenon (10).Compartmentalization of HCV variants has been mai...

Differences in the composition of the hepatitis C virus (HCV) quasispecies between plasma and blood mononuclear cells (BMC) strongly suggest that BMCs support viral replication. We examined the frequency of such compartmentalization, the cell types involved, the constraints exerted on the different variants, and the role of immunoglobulin-complexed variants. We screened the hypervariable region (HVR1) of HCV isolates from 14 HBsAg-and HIV-seronegative patients with chronic HCV infection. HCV RNA was amplified and cloned from plasma, the immunoglobulin G (IgG)-bound fraction, and total and sorted BMCs (CD19؉, CD8؉, CD4؉, and CD14؉ cells). Compartmentalization was estimated using a matrix correlation test. The ratio of nonsynonymous/synonymous substitutions (d N /d S ratio) was calculated for each compartment. HCV RNA was detected in 3/3 BMC, 11/11 CD19؉, 10/11 CD14؉, 4/11 CD8؉ and 0/11 CD4؉ cell samples. HVR1 sequences were significantly different between plasma and at least one cellular compartment in all nine cases analyzed, and between B cells (CD19؉) and monocytes ( H epatitis C virus (HCV) is an enveloped, positive-stranded RNA virus that circulates in vivo as a complex population of closely related variants referred to as a quasispecies. 1 Hepatitis C infection is frequently chronic, and its quasispecies nature probably plays a major role in viral persistence. 2,3 HCV genetic heterogeneity is particularly strong within a small hypervariable region (HVR1) that encodes a 27-amino acid peptide located at the N-terminus of the second envelope glycoprotein (E2) and is subjected to selective pressures by humoral and cellular immune responses. 4 One potential viral strategy explaining the persistence of HCV is infection of immune cells. Convincing evidence of HCV lymphotropism has been obtained in vitro in experiments showing that minor quasispecies components of strain H77 are selected in lymphoblastoid cell lines. 5 Subsequently, it was found that blood mononuclear cells (BMC) from chimpanzees that had been inoculated with this strain became infected by the same lymphotropic quasispecies components as those selected in vitro. 6 In vivo, HCV RNA has been detected in BMC by many teams. 7-14 Viral replication in these cells, shown by the detection of negatively stranded HCV RNA, an obligatory replication intermediate, generally occurs at a low level. 9,[15][16][17][18] Mutations in the 5Ј untranslated region-the viral internal ribosomal entry site-have been described in HCV strains isolated from BMCs. These mutations could influence the translational efficiency of the internal ribosomal entry site structure in lymphoblastoid cell lines 19 and point to HCV adaptation to BMCs. 6,20,21

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