Can HCV infection be cleared?

Long-term beneficial effects in sustained responders to interferon-alfa therapy for chronic hepatitis C

BACKGROUND/AIMS

Assessment of chronic hepatitis C outcome in sustained responders to interferon requires prolonged observation and close monitoring. We prospectively studied the impact of sustained response on histology and clinically relevant outcomes.

METHODS

The 47 sustained responders (ten with cirrhosis) from two interferon trials involving 235 chronic hepatitis C patients (81 with cirrhosis) were included. Hepatitis C virus (HCV) RNA was assessed every 6 months, liver histological changes from baseline, 6-12 and 48-72 months after treatment discontinuation.

RESULTS

The mean follow-up was 102 +/- 19 months. HCV RNA became undetectable in 36/47 responders. Four responders, who had remained viremic, later relapsed. The histology progressively improved in non-viremic and viremic patients, with a more marked improvement in the former (P = 0.0089), normalizing in 53 vs. 0% (P = 0.0220). No patient progressed to cirrhosis. One non-viremic cirrhotic patient developed a hepatocellular carcinoma. Non-responders from the two original trials had worse histological outcomes and those with cirrhosis had a higher rate of clinically relevant events compared with cirrhotics showing a sustained biochemical response (4.5 vs. 1.2 cases/100 person-years; CI for the difference, 0.3-6.3).

CONCLUSIONS

Most sustained, virological responders without cirrhosis normalize liver histology in the long-term and are cured of the disease. Sustained responders remaining viremic still show histological improvement, albeit to a lesser extent.

Analysis of successful immune responses in persons infected with hepatitis C virus

Although hepatitis C virus (HCV) infection is very common, identification of patients during acute infection is rare. Consequently, little is known about the immune response during this critical stage of the disease. We analyzed the T lymphocyte response during and after acute resolving HCV infection in three persons, using interferon (IFN)-gamma enzyme-linked immunospot (ELISPOT) and human histocompatibility leukocyte antigen (HLA) peptide tetramer assays. Acute infection was associated with a broadly directed T helper and cytotoxic T lymphocyte (CTL) response, which persisted after resolution of clinical hepatitis and clearance of viremia. At the earliest time point studied, highly activated CTL populations were observed that temporarily failed to secrete IFN-gamma, a "stunned" phenotype, from which they recovered as viremia declined. In long-term HCV-seropositive persons, CTL responses were more common in persons who had cleared viremia compared with those with persistent viremia, although the frequencies of HCV-specific CTLs were lower than those found in persons during and after resolution of acute HCV infection. These studies demonstrate a strong and persistent CTL response in resolving acute HCV infection, and provide rationale to explore immune augmentation as a therapeutic intervention in chronic HCV infection.

Influence of pre-treatment factors on outcome of interferon-alpha treatment of patients with chronic hepatitis C

A total of 172 Swedish patients treated with interferon-alpha for at least 24 weeks and followed-up > or =24 weeks after treatment was stopped were analysed for pre-treatment factors of importance for achieving a virological sustained response (SR). Furthermore, the predictive value for a virological SR of a positive or negative HCV RNA test at week 12 of treatment was evaluated. A low baseline viral load and genotype non-1b were pre-treatment factors indicating a favourable response. Thus, 44% (38/86) of patients with a low baseline viral load vs. only 16% (14/86) of those with a high viral load had a virological SR (p<0.0001). Of patients with a negative qualitative HCV RNA test after 12 weeks of interferon treatment, 46% (44/95) had virological SR, whereas only 5.9% (4/68) of those with a positive test had (p<0.0001). Prolonged ( > 6 months) treatment with interferon-alpha tended to increase the chance of virological SR (p<0.052).

Recurrent and new hepatitis C virus infection after liver transplantation

Chronic infection with the hepatitis C virus (HCV) is the most common reason for liver transplantation. We examined the results of laboratory tests for HCV on a cohort of patients who received a liver transplant between 1990 and 1994 at three large centers. Seven hundred twenty-two recipients and 604 donors were tested for antibody to HCV (anti-HCV) using a second-generation enzyme-linked immunoassay (EIA-2), followed by recombinant immunoblot (RIBA-2) and HCV RNA confirmation by reverse-transcription polymerase chain reaction (RT-PCR) (with genotyping and viral quantification). Diagnosis of posttransplantation infection required detection of serum HCV RNA that could be genotyped by sequencing or was repeatedly positive despite being unsequenceable. Twenty-five percent of transplantation candidates were seropositive for anti-HCV. Approximately 86% of anti-HCV-positive, 93% of RIBA-positive, and 97% of HCV RNA-positive candidates developed infection after transplantation. Pretransplantation HCV RNA was superior to RIBA-2 for predicting posttransplantation infection. Whereas HCV genotype was identified in nearly all candidates and changed little after transplantation, serum viral levels rose markedly after transplantation. Fifteen donors were either anti-HCV- or HCV RNA-positive. Recipients of grafts from donors with HCV RNA all developed infection, whereas infection was not detected in recipients of grafts from donors with anti-HCV but without detectable HCV RNA. The rate of new infection fell significantly (P =.02) after the introduction of EIA-2 screening of blood. Donor and candidate markers for HCV predict posttransplantation infection.

Persistence of viremia and the importance of long-term follow-up after acute hepatitis C infection

The purpose of this investigation was to prospectively characterize acute hepatitis C virus (HCV) infections and to evaluate the hypothesis that the outcome is affected by identifiable clinical or viral factors. One hundred forty-two people with a history of illicit drug use who were HCV antibody-negative in 1988 were followed semiannually through 1996. HCV seroconversion (second generation enzyme immunoassay and recombinant immunoblot assay) was recognized in 43 (30%) of the participants, who were followed up for a median of 72 months. HCV RNA was detected and quantified by polymerase chain reaction in a median of 10 specimens per participant and showed two distinct patterns of viremia: viral clearance was noted in 6 (14%) of the participants, and viral persistence was observed in 37 (86%) of the participants. Subjects with viral clearance were more likely to be white (P =.004), have jaundice (P =.03), and have lower peak viral titer (P =.003). However, the outcome for a given person could not be predicted by clinical features, RNA level, or HCV subtype (as ascertained by analysis of core-E1 complementary DNA sequence). No acute infections were recognized by health care providers. At the time of seroconversion, HCV RNA was detectable in 81% of participants, and recombinant immunoblot assay (RIBA) was positive in 85% of participants. We conclude that approximately 85% of people with acute hepatitis C develop persistent viremia. However, acute infections are uncommonly recognized clinically, underscoring the importance of screening individuals at risk. Long-term follow-up, but no single laboratory test, is necessary to ascertain the outcome and in some cases make the diagnosis of acute HCV infection.