Ultracentrifugation and concentration of a large volume of serum for HCV RNA during treatment may predict sustained and relapse response in chronic HCV infection.

The ability to predict accurately a sustained response during therapy in patients with hepatitis C virus (HCV) infection is unavailable. The aim of this study was to differentiate, during therapy, patients who would relapse from those with a sustained response by ultracentrifugation for residual serum HCV RNA. Sixty-one specimens (from 32 patients) collected during interferon therapy were assessed by ultracentrifugation. All were negative using a quantitative polymerase chain reaction (PCR) (detection limit < or = 100 copies/ml). One-milliliter aliquots were ultracentrifuged at 23,000 x g (160 min), and then the nucleic acid pellet was extracted, precipitated, and resuspended. Qualitative PCR was carried out in quadruplicate using two separate 5'UTR primer sets (8 results/specimen). A specimen was positive if > or = 1 gels was positive compared to controls. At weeks 12 and 24, 9/9 (100%) sustained response patients were negative by ultracentrifugation. In the 23 relapse patients at week 12, 7/12 specimens were positive; at week 24, 7/14 were positive. Earlier time points could not differentiate the patients' eventual response to therapy. The predictive value of a positive ultracentrifugation test for relapse at week 12 or 24 was 100%. The predictive value of a negative test for sustained response was 62% and 50% at week 12 and 24, respectively. These preliminary results indicate that patients with an eventual sustained response will have no detectable serum HCV RNA by week 12 or week 24. A positive result is 100% predictive of relapse.