biochemical and histological improvement. 3,4 Several factors Hepatitis C virus (HCV) genotype 1b and high precan predict a poor response to interferon therapy, e.g., high treatment virus load are predictive factors of poor repretreatment virus load, genotype 1b, advanced histological sponse to interferon therapy in patients with chronic changes, lower serum ferritin level, and a high degree of hepatitis C. To further examine the factors predicting amino acid substitutions of the hypervariable region (for rethe response to interferon in patients with genotype 1b view, see Davis 5 ).
infection, we analyzed 110 consecutive patients with
Recently, Enomoto et al. 6 compared amino acid sequences HCV who were treated with a total of 624 million units of of interferon-sensitive and -resistant quasispecies by analyzlymphoblastoid interferon alfa. Thirty-six patients (33%) ing serum samples of three patients infected with genotype were responders, while the remaining 74 patients (67%)
1b HCV before and after interferon therapy. They identified were nonresponders. Multivariate analysis showed that in the interferon-sensitive strains of HCV clusters of amino a high virus titer (assessed by serum core protein level, acid substitutions in the carboxyl terminal half of the NS5A P Å .0021) and the presence of more than two amino acid region (codon 2154-2383). They also detected multiple missubstitutions in the interferon sensitivity-determining sense mutations exclusively in a 40-amino acid stretch (coregion (ISDR) (P Å .0036) correlated significantly with don 2209-2248) in interferon-sensitive HCV isolates. 6,7 In the response to interferon therapy. Because mutations contrast, the sequences of interferon-resistant HCV strains analyzed by direct sequencing of polymerase chain reacwere identical to those of prototype genotype 1b. They desigtion (PCR) products may reflect artifacts of direct senated the region with these amino acid substitutions as the quencing, we further analyzed quasispecies of HCV in interferon sensitivity-determining region (ISDR) 6 and this region by cloning and sequencing. Although PCRshowed, by multivariate analysis, that the substitution in based analysis of responders with multiple amino acid the ISDR was the best predictive factor of the response to substitutions in the ISDR showed the presence of a small interferon therapy. 7 These results were potentially of great amount of wild-type strain in their serum, the results importance but were based on relatively few patients treated obtained by direct sequencing and cloning were essenwith varying regimens of interferon. To provide further evitially the same. A longitudinal study of quasispecies in dence for or against the predictive power of amino acid substi-2 patients who showed a dramatic change in the virus titer showed no conversion from wild type to mutant or tutions in the ISDR, we used a large sample of patients with vice versa. Our results indicate that amino acid substitu-HCV genotype 1b seen in our unit who were treated with a tions and virus load are independent predictors of the single regimen of interferon. response to interferon therapy. The ability of some pa-
We also examined whether the results obtained by direct tients with no mutation in the ISDR or high virus load sequencing reflected the sequences of viruses present in seto eliminate the virus suggests the presence of other unrum samples analyzed by cloning of polymerase chain reacidentified factors, host or viral, that influence the retion (PCR) products. sponse to interferon therapy. (HEPATOLOGY 1997;25:745-749.)
PATIENTS AND METHODS
Patients. We studied a total of 110 consecutive adult patients with Chronic hepatitis C often evolves after an acute hepatitis HCV genotype 1b who were treated by lymphoblastoid interferon C virus (HCV) infection, with cirrhosis developing in at least alfa between September 1992 and July 1994 at the Department of 20% of chronically infected patients. 1,2 Currently, interferon Gastroenterology, Toranomon Hospital. The experimental protocol is the only drug that induces viral clearance and marked was approved by the Ethics Review Committee for Human Experi- mentation, and informed consent was obtained from every patient. Each patient was treated with 6 million units of interferon intramuscularly every day for 8 weeks, followed by the same dose three times a week for 16 weeks, thus providing a total dose of 624 million units.