Patients with dual infection with hepatitis B virus (HBV) and delta virus (HDV) responded poorly to interferon (IFN) therapy. Little is known about the effect of IFN therapy in patients with HBV and hepatitis C virus (HCV) dual infection. The patients in two randomized controlled trials with chronic HBV infection were retrospectively assayed for HCV markers. The HBV responses to IFN therapy in patients with and without HCV markers were compared. An open trial was conducted in 4 patients who had lost their serum HBV surface antigen (HBsAg) but had continuing HCV viremia and hepatitis. Of the 15 patients seropositive for HCV marker(s), only 1 (6.7%) responded with seroclearance of HBV DNA and HBV e antigen, as compared with 46 (28%) of 164 HCV-negative patients (p = 0.058). Icteric hepatitis developed in 1 patient on emergence of serum HCV RNA in association with seroclearance of HBV DNA. In contrast, good response was demonstrated in 3 of the 4 patients who had lost serum HBsAg before therapy. The results suggest that IFN therapy is not only of limited value in patients with dual infection with HBV and HCV but also has a potential risk of severe hepatitis if the clearance of one virus removes its suppressive effect on and facilitates the emergence of the other. However, patients with continuing HCV hepatitis after termination of the chronic HBsAg carrier state responded well to IFN therapy.

Gut 2002;51:95-99 Background and aims: The aim of this study was to assess whether underlying chronic hepatitis B virus (HBV) infection interferes with persistence of hepatitis C virus (HCV) infection and humoral immune responses to HCV in acute HCV infection. Methods: Serial sera from 12 patients with acute HCV infection (group A) and 12 hepatitis B surface antigen (HBsAg) carriers with acute HCV infection (seven anti-hepatitis B e antigen (anti-HBe) positive (group B1) and five hepatitis B e antigen (HBeAg) positive (group B2)) were tested for HCV RNA by polymerase chain reaction, and anti-HCV by third generation enzyme immunoassay and confirmatory assay. Serial serum samples from HBsAg carriers were also tested for HBeAg, anti-HBe, and HBV DNA by hybridisation assay. Results: Persistent HCV viraemia for more than six months was significantly more frequent in groups A (83%) and B1 (86%) than in group B2 (0%). Anti-HCV was detected in 100% and 86% of group A and group B1 one month after onset while only one group B2 patient was transiently anti-HCV positive 1-2 months after onset. Of the latter, three had anti-core 1 less than two months after onset while no patient responded to other HCV antigens. Overall, of six HBsAg carriers with acute self limiting HCV infection, only one had transient anti-HCV and three had transient anti-core 1. HBV DNA became undetectable transiently in four and persistently in one group B2 patient. Conclusion: The presence of active HBV replication can inhibit the persistence of HCV infection and antibody responses to HCV. Acute HCV infection in HBsAg carriers with active HBV replication usually presents transient HCV viraemia with poor antibody responses to HCV.