We have previously reported that levels of large and buoyant hepatitis C virus particles surge in a very-low density fraction (VLDF, d<1.025 g/ml) of density gradients over a six hour time course after patients with chronic hepatitis C infection consume a high-fat meal. HCV particles in the VLDF (HCV-VLDF) were found to be associated with not only hepatically derived VLDL, HEPATOLOGY, VOLUME 52, NUMBER 4 (SUPPL) AASLD ABSTRACTS 819A but also with intestinally derived chylomicrons. In the
... study, we further sought to characterize the derivation of HCV-VLDF to observe if they could be produced by transfer of higher density HCV particles transferring onto triglyceride-rich lipoproteins (TRLs) extracellularly, and we sought to examine the destination of HCV-VLDF to see if they migrated into the adjacent density fraction or directly cleared from the VLDF. Methods: Fasting patients (n=9) with chronic hepatitis C infection were administered a high-fat milkshake and 2 ml of plasma was fractionated into 10 1 ml fractions by iodixanol density gradient ultracentrifugation at several times during a 6 hour time course. HCV RNA was measured in each fraction. Results: Very little of HCV-VLDF migrates into the adjacent density fraction by being subject to lipolysis, and instead directly and rapidly clears from VLDF. The mean half-life of HCV-VLDF of 9 patients is 95 minutes with a standard deviation of 45 minutes. Incubation of fasting plasma from an HCV patient mixed with plasma from an uninfected volunteer resulted in an enrichment in HCV-VLDF compared to incubation with PBS, due to TRL in volunteer plasma. This enrichment was further enhanced when mixing postprandial plasma or chylomicron-like lipid emulsions compared to fasting plasma, consistent with HCV-VLDF dependent on TRL levels. These data were recapitulated with patient plasma infected with genotypes 1, 3, and 4, as well as in vitro generated J6/JFH HCV particles (HCVcc). Incubation of HCVcc with postprandial serum slightly enhanced infectivity compared to fasting serum. Conclusions: The clearance rate of HCV-VLDF (95 minutes) is faster than previously published plasma borne HCV particles (166 minutes, Neumann AU et al, Science 1998 282, 103). This is consistent with the concept that HCV may gain infectivity by piggy-backing onto high-turnover TRL remnant clearance pathway. Chylomicron-associated viruses are in part generated by virion association while in the vascular compartment. The exchange phenomena of virions onto TRLs reveal a virus-host interaction which may prove to be a useful therapeutic target.